Outdoor unit of air conditioning device, and air conditioning device

Abstract

Provided are an outdoor unit of an air conditioner and an air conditioner applicable to both of a heat recovery type and a general multi-type and capable of suppressing congestion of refrigerator oil in an outdoor pipe closed when applied to the multi-type. An outdoor unit (5) includes: a seventh branch pipe (67) connecting an outdoor heat exchanger (13) and an indoor unit (6A, 6B, ...); a tenth pipe (70) that is one of branches of a first switching valve (12A) and connects a compressor (2) and the indoor unit (6A, 6B, ...); and an eighth branch pipe (68A) that is connected to one of the branches of the first switching valve (12A) and bypasses the first switching valve (12A) to connect the compressor (2) and the indoor unit (6A, 6B, ...). The eighth branch pipe (68A) includes a main flow pipe portion (85) through which refrigerant to be sucked into the compressor (2) through the first switching valve (12A) flows and a trap part (86) that intersects the main flow pipe portion (85), branches off, and then goes downwards.

Description

TECHNICAL FIELD

[0001] Embodiments of the present invention relate to an outdoor unit of an air conditioner, and an air conditioner.BACKGROUND

[0002] An air conditioner provided with an outdoor unit, a plurality of indoor units, a plurality of switching units, a first connecting pipe, a second connecting pipe, and a third connecting pipe is known. The outdoor unit includes an outdoor heat exchanger and a compressor. The outdoor unit includes an outdoor first pipe that connects the outdoor heat exchanger and the first connecting pipe, an outdoor second pipe that connects the compressor and the second connecting pipe, and an outdoor third pipe that connects the compressor and the third connecting pipe. Each indoor unit includes an indoor heat exchanger.

[0003] Each switching unit includes an indoor first pipe that connects the indoor heat exchanger and the first connecting pipe, an indoor second pipe that connects the indoor heat exchanger and the second connecting pipe, an indoor third pipe that connects the indoor heat exchanger and the third connecting pipe, and an indoor third pipe valve provided in the indoor third pipe. Each indoor third pipe valve switches a connection state of the three pipes of the outdoor unit and the two pipes of each indoor unit.

[0004] This conventional air conditioner can not only execute a heating operation in all of the indoor units or execute a cooling operation in all of the indoor units but also execute the heating operation in some indoor units and execute the cooling operation in the remaining indoor units.PRIOR ART DOCUMENTPATENT DOCUMENT

[0005] [Patent Document 1] JP 2017-180882 ASUMMARYPROBLEMS TO BE SOLVED BY INVENTION

[0006] The conventional air conditioner is a so-called heat-recovery (heat recovery system) multi-type air conditioner.

[0007] When the outdoor unit and the plurality of indoor units are directly connected by two connecting pipes, the first connecting pipe and the second connecting pipe for example, without interposing the switching units, the conventional air conditioner functions as a multi-type air conditioner that executes the heating operation in all of the indoor units or executes the cooling operation in all of the indoor units. In that case, one outdoor pipe, the outdoor third pipe for example, of the three outdoor pipes (the outdoor first pipe, the outdoor second pipe, and the outdoor third pipe) is closed at an end without being connected to a connecting pipe.

[0008] The outdoor third pipe with the closed end becomes a so-called blind alley. There is a risk that a refrigerant and refrigerator oil contained in the refrigerant stay in the blind alley pipe. When a large amount of the refrigerator oil stays in the blind alley, there is a risk that lubrication of the compressor becomes insufficient.

[0009] An object of the present invention is to provide an outdoor unit of an air conditioner and the air conditioner applicable to both of a heat recovery type and a general multi-type and capable of suppressing congestion of refrigerator oil in an outdoor pipe closed when applied to the multi-type.MEANS FOR SOLVING PROBLEM

[0010] To achieve the above object, an outdoor unit of an air conditioner according to an embodiment of the present invention includes: a compressor that compresses a refrigerant; an outdoor heat exchanger that exchanges heat between the refrigerant and outdoor air; a first switching valve that shuts off connection of a discharge side of the compressor and indoor heat exchangers of all of indoor units to cause the outdoor heat exchanger to function as a condenser, or connects the discharge side of the compressor to the indoor heat exchanger of at least one of the indoor units to cause the indoor heat exchanger of the at least one of the indoor units to function as a condenser; a second switching valve that connects the discharge side of the compressor to the outdoor heat exchanger to cause the outdoor heat exchanger to function as a condenser, or connects a suction side of the compressor to the outdoor heat exchanger to cause the outdoor heat exchanger to function as an evaporator; an outdoor first pipe that connects the outdoor heat exchanger and the indoor units; an outdoor second pipe that is one of branches of the first switching valve and connects the compressor and the indoor units; and an outdoor third pipe that is connected to one of the branches of the first switching valve and makes a detour around the first switching valve to connect the compressor and the indoor units. The outdoor third pipe includes a main flow pipe portion through which the refrigerant to be sucked into the compressor through the first switching valve flows and a trap portion that intersects the main flow pipe portion, branches off, and then goes downwards.

[0011] Moreover, to achieve the above object, an outdoor unit of an air conditioner according to an embodiment of the present invention includes: a compressor that compresses a refrigerant; an outdoor heat exchanger that exchanges heat between the refrigerant and outdoor air; a first switching valve that shuts off connection of a discharge side of the compressor and indoor heat exchangers of all of indoor units to cause the outdoor heat exchanger to function as a condenser, or connects the discharge side of the compressor to the indoor heat exchanger of at least one of the indoor units to cause the indoor heat exchanger of the at least one of the indoor units to function as a condenser; a second switching valve that connects the discharge side of the compressor to the outdoor heat exchanger to cause the outdoor heat exchanger to function as a condenser, or connects a suction side of the compressor to the outdoor heat exchanger to cause the outdoor heat exchanger to function as an evaporator; an outdoor first pipe that connects the outdoor heat exchanger and the indoor units; an outdoor second pipe that is one of branches of the first switching valve and connects the compressor and the indoor units; and an outdoor third pipe that is connected to one of the branches of the first switching valve and is connected to the compressor. The outdoor third pipe makes a detour around the first switching valve to connect the compressor and the indoor units when the outdoor first pipe, the outdoor second pipe, and the outdoor third pipe are connected to the indoor units via a plurality of switching units that switch a flowing direction of the refrigerant flowing to the indoor units. The outdoor third pipe includes a main flow pipe portion through which the refrigerant to be sucked into the compressor through the first switching valve flows and a trap portion that intersects the main flow pipe portion, branches off, and then goes downwards when the outdoor first pipe and the outdoor second pipe are connected to the indoor units without interposing the plurality of switching units.

[0012] Furthermore, it is preferable that the main flow pipe portion of the outdoor unit of the air conditioner according to the embodiment of the present invention include a straight pipe portion that extends vertically downwards from a branch portion of the main flow pipe portion and the trap portion such that liquid contained in the refrigerant flows vertically downwards.

[0013] Furthermore, it is preferable that the outdoor unit of the air conditioner according to the embodiment of the present invention include a recovery pipe connecting the outdoor third pipe to a suction side of the compressor.

[0014] Moreover, to achieve the above object, an air conditioner according to another embodiment of the present invention includes: the outdoor unit; and a plurality of indoor units that exchange heat between the refrigerant and indoor air. The outdoor unit includes an outdoor expansion valve connected to a discharge side of the outdoor heat exchanger. The indoor units each include an indoor heat exchanger and an indoor expansion valve connected to the indoor heat exchanger. Flowing directions of the refrigerant flowing to the plurality of the indoor units are caused to be different from each other to mix the indoor units that perform a cooling operation and the indoor units that perform a heating operation when a plurality of switching units that switch a flowing direction of the refrigerant flowing to the corresponding indoor units are provided. The flowing directions of the refrigerant flowing to the plurality of the indoor units are unified so as to cause the refrigerant to be sucked into the compressor through the first switching valve during the cooling operation and to cause the refrigerant to be sent to the plurality of the indoor units through the first switching valve during the heating operation, and all of the indoor units are caused to perform the cooling operation or the heating operation when the plurality of switching units are not provided.EFFECTS OF INVENTION

[0015] The present invention provides an outdoor unit of an air conditioner and the air conditioner applicable to both of a heat recovery type and a general multi-type and capable of suppressing congestion of refrigerator oil in an outdoor pipe closed when applied to the multi-type.BRIEF DESCRIPTION OF DRAWINGS

[0016] Fig. 1 is a block diagram of an air conditioner according to an embodiment of the present invention. Fig. 2 is a diagram illustrating a first case of a flow of a refrigerant in a mixed cooling operation state of the air conditioner according to the embodiment of the present invention. Fig. 3 is a diagram illustrating a second case of the flow of the refrigerant in the mixed cooling operation state of the air conditioner according to the embodiment of the present invention. Fig. 4 is a diagram illustrating a case of the flow of the refrigerant in a mixed heating operation state of the air conditioner according to the embodiment of the present invention. Fig. 5 is a block diagram of a second form of the air conditioner according to the embodiment of the present invention. Fig. 6 is a schematic diagram of a comparative example of an eighth branch pipe of an outdoor unit according to the embodiment of the present invention. Fig. 7 is a schematic diagram of a first example of the eighth branch pipe of the outdoor unit according to the embodiment of the present invention. Fig. 8 is a schematic diagram of a second example of the eighth branch pipe of the outdoor unit according to the embodiment of the present invention. Fig. 9 is a schematic diagram of a third example of the eighth branch pipe of the outdoor unit according to the embodiment of the present invention. Fig. 10 is a schematic diagram of a fourth example of the eighth branch pipe of the outdoor unit according to the embodiment of the present invention. Fig. 11 is a block diagram of a third form of the air conditioner according to the embodiment of the present invention. DETAILED DESCRIPTION

[0017] Embodiments of an air conditioner and an outdoor unit of the air conditioner according to the present invention will be described with reference to Fig. 1 to Fig. 11. Note that same or corresponding configurations are denoted by same reference signs in a plurality of drawings.

[0018] Fig. 1 is a block diagram of the air conditioner according to the embodiment of the present invention.

[0019] As illustrated in Fig. 1, an air conditioner 1 according to the present invention is a heat-recovery (heat recovery system) multi-type air conditioner. The air conditioner 1 includes at least one outdoor unit 5 provided with a compressor 2 that compresses a refrigerant, a plurality of indoor units 6A, 6B,..., and a plurality of switching units 7A, 7B,... capable of switching a flowing direction of the refrigerant flowing to the indoor units 6A, 6B,.... In addition, the air conditioner 1 includes refrigerant piping 8 that successively connects the outdoor unit 5, the plurality of switching units 7A, 7B,..., and the plurality of indoor units 6A, 6B,... to circulate the refrigerant.

[0020] The air conditioner 1 circulates the refrigerant between the outdoor unit 5 and the plurality of indoor units 6A, 6B,..., and performs a full cooling operation of causing the outdoor unit 5 to function as a condenser and causing all of the indoor units 6A, 6B,... to function as evaporators, and a full heating operation of causing the outdoor unit 5 to function as an evaporator and causing all of the indoor units 6A, 6B,... to function as condensers.

[0021] Further, the air conditioner 1 can mix the indoor units 6A, 6B,... that perform a cooling operation and the indoor units 6A, 6B,... that perform a heating operation by making the flowing direction of the refrigerant flowing to the plurality of indoor units 6A, 6B,... be different from each other. The air conditioner 1 performs a mixed cooling operation of causing the outdoor unit 5 to function as a condenser, causing some indoor units 6A and 6B to function as evaporators, and causing the remaining indoor unit 6C to function as a condenser, and a mixed heating operation of causing the outdoor unit 5 to function as an evaporator, causing some indoor units 6A and 6B to function as condensers, and causing the remaining indoor unit 6C to function as an evaporator. The mixed cooling operation is an operation for cooling, in which the cooling operation is performed in a large number of the indoor units 6A and 6B and the heating operation is performed in a small number of the indoor unit 6C. The mixed heating operation is an operation mainly for heating, in which the heating operation is performed in a large number of the indoor units 6A and 6B and the cooling operation is performed in a small number of the indoor unit 6C.

[0022] The outdoor unit 5 includes the compressor 2 that compresses and discharges the sucked refrigerant, an oil separator 11 provided on a discharge side of the compressor 2, at least three switching valves 12A, 12B, and 12C that switch a circulation route of the refrigerant circulated between the outdoor unit 5 and the indoor units 6A, 6B,..., two outdoor heat exchangers 13 that exchange heat between the refrigerant and outdoor air, two outdoor expansion valves 15 that reduce a pressure of the refrigerant flowing from the indoor units 6A, 6B,... to the respective outdoor heat exchangers 13, and an accumulator 16 provided on a suction side of the compressor 2. In addition, the outdoor unit 5 includes an outdoor fan 17 that causes the outdoor air heat-exchanged in the two outdoor heat exchangers 13 to flow. Further, the outdoor unit 5 includes an inverter circuit 18 that controls an operating frequency of the compressor 2, and a control unit 19 that controls the inverter circuit 18.

[0023] The plurality of indoor units 6A, 6B,... all have a similar configuration. Hereinafter, one representative indoor unit 6A will be described. The indoor unit 6A includes an indoor heat exchanger 21A that exchanges heat between the refrigerant and indoor air, and an indoor expansion valve 22A that reduces the pressure of the refrigerant flowing from the outdoor unit 5 to the indoor heat exchanger 21A. In addition, the indoor unit 6A includes an indoor fan 23A that causes the indoor air heat-exchanged in the indoor heat exchanger 21A to flow. Further, the indoor unit 6A includes an indoor control unit (not illustrated).

[0024] The plurality of switching units 7A, 7B,... all have a similar configuration. Hereinafter, one representative switching unit 7A will be described. The switching unit 7A includes a discharge gas pipe shutoff valve 25A that allows or shuts off flow of the refrigerant from the compressor 2 to the indoor heat exchanger 21A, and a suction gas pipe shutoff valve 26A that allows or shuts off the flow of the refrigerant from the indoor heat exchanger 21A to the compressor 2. Closing the discharge gas pipe shutoff valve 25A and opening the suction gas pipe shutoff valve 26A cause the indoor heat exchanger 21A of the indoor unit 6A to function as an evaporator. Opening the discharge gas pipe shutoff valve 25A and closing the suction gas pipe shutoff valve 26A cause the indoor heat exchanger 21A to function as a condenser.

[0025] The compressor 2 is housed in the outdoor unit 5. The compressor 2 changes the operating frequency by output of the inverter circuit 18. The air conditioner 1 may include the plurality of compressors 2. In that case, the number of the inverter circuits 18 is preferably same as the number of the compressors 2 and each inverter circuit 18 individually controls the operating frequency of the corresponding compressor 2. The compressor 2 changes the operating frequency by known inverter control. The compressor 2 may be operated at a fixed operating frequency.

[0026] The compressor 2 includes a sealed case, a compression mechanism that compresses the refrigerant, and an electric motor that drives the compression mechanism. The sealed case houses the compression mechanism and the electric motor. The sealed case stores refrigerator oil that lubricates the compression mechanism. The discharge side of the compressor 2 is connected to the oil separator 11. The suction side of the compressor 2 is connected to the accumulator 16. Further, the compressor 2 includes an accumulator 2a of a capacity smaller than that of the accumulator 16. This small-capacity accumulator 2a is a gas-liquid separator that separates a gas refrigerant and a liquid refrigerant and sends the gas refrigerant to the compressor 2. The small-capacity accumulator 2a is also referred to as a suction muffler or a suction cup, and is provided between the suction side of the compressor 2 and the accumulator 16 of a large capacity.

[0027] The oil separator 11 separates the gas refrigerant and the refrigerator oil discharged from the compressor 2. The refrigerator oil separated in the oil separator 11 is returned to the compressor 2 through a return pipe (not illustrated). The oil separator 11 is a centrifugal separator for example.

[0028] The two outdoor heat exchangers 13 and the indoor heat exchanger 21A are fin-and-tube type heat exchangers for example. The two outdoor heat exchangers 13 and the indoor heat exchanger 21A include a plurality of paths 28 through which the refrigerant flows, a header 29 that distributes the refrigerant to the plurality of paths 28 or merges the refrigerant distributed to the plurality of paths 28, and a plurality of fins (not illustrated) that extend orthogonally to the plurality of paths 28.

[0029] The two outdoor heat exchangers 13 include a main heat exchanger 31a as a first outdoor heat exchanger, and an auxiliary heat exchanger 31b as a second outdoor heat exchanger connected in parallel with the main heat exchanger 31a. The main heat exchanger 31a is connected to the second switching valve 12B. The auxiliary heat exchanger 31b is connected to the third switching valve 12C.

[0030] The switching valves 12A, 12B, and 12C are electrically connected to the control unit 19 by a signal line (not illustrated), respectively. The air conditioner 1 switches the cooling operation (the flow of the refrigerant indicated with solid line arrows in Fig. 1) and the heating operation (the flow of the refrigerant indicated with broken line arrows in Fig. 1) by switching the flowing direction of the refrigerant using the three switching valves 12A, 12B, and 12C.

[0031] The second switching valve 12B connects the discharge side of the compressor 2 to the main heat exchanger 31a to cause the main heat exchanger 31a to function as a condenser. In addition, the second switching valve 12B connects the suction side of the compressor 2 to the main heat exchanger 31a to cause the main heat exchanger 31a to function as an evaporator.

[0032] The third switching valve 12C connects the discharge side of the compressor 2 to the auxiliary heat exchanger 31b to cause the auxiliary heat exchanger 31b to function as a condenser. In addition, the third switching valve 12C connects the suction side of the compressor 2 to the auxiliary heat exchanger 31b to cause the auxiliary heat exchanger 31b to function as an evaporator.

[0033] The first switching valve 12A shuts off connection of the discharge side of the compressor 2 and indoor heat exchangers 21A, 21B,... of all of the indoor units 6A, 6B,... to cause the two outdoor heat exchangers 13 to function as condensers, or connects the discharge side of the compressor 2 to the indoor heat exchangers 21A, 21B,... of at least one of the indoor units 6A, 6B,... to cause the indoor heat exchangers 21A, 21B,... of at least one of the indoor units 6A, 6B,... to function as condensers.

[0034] The two outdoor expansion valves 15 are a first outdoor expansion valve 15a connected to the main heat exchanger 31a and a second outdoor expansion valve 15b connected to the auxiliary heat exchanger 31b.

[0035] The main heat exchanger 31a is disposed between the second switching valve 12B and the first outdoor expansion valve 15a, and the auxiliary heat exchanger 31b is disposed between the third switching valve 12C and the second outdoor expansion valve 15b. That is, the refrigerant is distributed on an inlet side of the main heat exchanger 31a and the auxiliary heat exchanger 31b, and is merged on an outlet side of the main heat exchanger 31a and the auxiliary heat exchanger 31b.

[0036] The outdoor fan 17 and the indoor fan 23A are, for example, axial fans. The outdoor fan 17 accelerates heat exchange of the outdoor air and the refrigerant flowing to the two outdoor heat exchangers 13. The indoor fan 23A accelerates heat exchange of the indoor air and the refrigerant flowing to the indoor heat exchanger 21A.

[0037] The two outdoor expansion valves 15 and the indoor expansion valve 22A are, for example, electronic expansion valves (Pulse Motor Valves, PMV) for which a valve opening degree is adjustable. The electronic expansion valve includes a valve box provided with a through-hole, and a needle as a valve body movable forward and backward to / from the through-hole. When the needle closes the through-hole, the electronic expansion valve shuts off the flow of the refrigerant. At that time, the electronic expansion valve is in a closed state and the valve opening degree of the electronic expansion valve is smallest. When the needle is most separated from the through-hole, the electronic expansion valve maximizes a flow rate of the refrigerant. At that time, the electronic expansion valve is in a fully open state, and the valve opening degree of the electronic expansion valve is largest.

[0038] The accumulator 16 is a gas-liquid separator that separates the gas refrigerant and the liquid refrigerant and sends the gas refrigerant to the compressor 2.

[0039] The discharge gas pipe shutoff valve 25A and the suction gas pipe shutoff valve 26A may be a stop valve or may be an electronic expansion valve for which the opening degree is adjustable. The discharge gas pipe shutoff valve 25A allows or shuts off the flow of the refrigerant that is discharged from the compressor 2 and discharged to the indoor heat exchanger 21A through the first switching valve 12A. The suction gas pipe shutoff valve 26A allows or shuts off the flow of the refrigerant that is sucked from the indoor heat exchanger 21A to the compressor 2.

[0040] The refrigerant piping 8 includes three connecting pipes 35, 36, and 37 that connect the outdoor unit 5 and the plurality of switching units 7A, 7B,... to cause the refrigerant to move back and forth, and two connecting pipes 38A and 39A that connect the switching unit 7A and the indoor unit 6A to cause the refrigerant to move back and forth. The connecting pipes 35, 36, and 37 are branch pipes that connect the one outdoor unit 5 and the plurality of switching units 7A, 7B,....

[0041] The outdoor unit 5 includes a pipe connecting part 41 that connects the connecting pipe 35, a pipe connecting part 42 that connects the connecting pipe 36, and a pipe connecting part 43 that connects the connecting pipe 37.

[0042] The switching unit 7A includes a pipe connecting part 45A that connects the connecting pipe 35, a pipe connecting part 46A that connects the connecting pipe 36, and a pipe connecting part 47A that connects the connecting pipe 37.

[0043] The connecting pipe 35 is the branch pipe that connects the one pipe connecting part 41 and a plurality of pipe connecting parts 45A, 45B,.... The connecting pipe 36 is the branch pipe that connects the one pipe connecting part 42 and a plurality of pipe connecting parts 46A, 46B,.... The connecting pipe 37 is the branch pipe that connects the one pipe connecting part 43 and a plurality of pipe connecting parts 47A, 47B,....

[0044] In addition, the switching unit 7A includes a pipe connecting part 48A that connects the connecting pipe 38A and a pipe connecting part 49A that connects the connecting pipe 39A.

[0045] The indoor unit 6A includes a pipe connecting part 51A that connects the connecting pipe 38A and a pipe connecting part 52A that connects the connecting pipe 39A.

[0046] The pipe connecting parts 41, 42, and 43 of the outdoor unit 5, the pipe connecting parts 45A, 45B, 45C, 46A, 46B, 46C, 47A, 47B, and 47C on the side of the outdoor unit 5 of the respective switching units 7A, 7B,..., the pipe connecting parts 48A, 48B, 48C, 49A, 49B, and 49C on the side of the indoor units 6A, 6B,... of the respective switching units 7A, 7B,..., and the pipe connecting parts 51A, 51B, 51C, 52A, 52B, and 52C of the indoor units 6A, 6B,... are packed valves (back seating type valves) having a structure that prevents the refrigerant from being discharged to the atmosphere.

[0047] The refrigerant piping 8 successively connects the compressor 2, the oil separator 11, the three switching valves 12A, 12B, and 12C, the two outdoor heat exchangers 13, the two outdoor expansion valves 15, a plurality of indoor expansion valves 22A, 22B,..., the plurality of indoor heat exchangers 21A, 21B,..., a plurality of discharge gas pipe shutoff valves 25A, 25B,..., a plurality of suction gas pipe shutoff valves 26A, 26B,..., and the accumulator 16.

[0048] The refrigerant piping 8 inside the outdoor unit 5 includes a first pipe 61 that connects the discharge side of the compressor 2 and the oil separator 11, a second branch pipe 62 that connects the oil separator 11 and the three switching valves 12A, 12B, and 12C, a third pipe 63 that connects the second switching valve 12B and one of the outdoor heat exchangers 13, a fourth pipe 64 that connects the third switching valve 12C and the other outdoor heat exchanger 13, a fifth pipe 65 that connects one of the outdoor heat exchangers 13 and one of the outdoor expansion valves 15, a sixth pipe 66 that connects the other outdoor heat exchanger 13 and the other outdoor expansion valve 15, and a seventh branch pipe 67 that connects the two outdoor expansion valves 15 and the pipe connecting part 41.

[0049] The first pipe 61 and the second branch pipe 62 are refrigerant feed pipes connected to the discharge side of the compressor 2 regardless of a switching state of the three switching valves 12A, 12B, and 12C.

[0050] Further, the refrigerant piping 8 inside the outdoor unit 5 includes an eighth branch pipe 68 that connects the pipe connecting part 43, the three switching valves 12A, 12B, and 12C, and the accumulator 16, a ninth pipe 69 that connects the accumulator 16 and the suction side of the compressor 2, and a 10th pipe 70 that connects the first switching valve 12A and the pipe connecting part 42.

[0051] The eighth branch pipe 68 and the ninth pipe 69 are refrigerant return pipes connected to the suction side of the compressor 2 regardless of the switching state of the three switching valves 12A, 12B, and 12C.

[0052] The refrigerant piping 8 inside each switching unit 7A includes an 11th pipe 71A that connects the pipe connecting part 45A and the pipe connecting part 48A, a 12th branch pipe 72A that connects the discharge gas pipe shutoff valve 25A, the suction gas pipe shutoff valve 26A, and the pipe connecting part 49A, a 13th pipe 73A that connects the pipe connecting part 46A and the discharge gas pipe shutoff valve 25A, and a 14th pipe 74A that connects the pipe connecting part 47A and the suction gas pipe shutoff valve 26A.

[0053] The refrigerant piping 8 inside each indoor unit 6A includes a 15th pipe 75A that connects the pipe connecting part 51A and the indoor expansion valve 22A, a 16th pipe 76A that connects the indoor expansion valve 22A and the indoor heat exchanger 21A, and a 17th pipe 77A that connects the indoor heat exchanger 21A and the pipe connecting part 52A.

[0054] The inverter circuit 18 rectifies AC power supplied from a commercial AC power source E, converts rectified DC power to a frequency according to a command of the control unit 19, and outputs it to the electric motor of the compressor 2. That is, the inverter circuit 18 can control the operating frequency of the compressor 2.

[0055] The control unit 19 controls the inverter circuit 18 to control the operating frequency of the compressor 2. In addition, the control unit 19 controls the three switching valves 12A, 12B, and 12C, the plurality of discharge gas pipe shutoff valves 25A, 25B,..., and the plurality of suction gas pipe shutoff valves 26A, 26B,... based on an operation input to a remote controller (not illustrated), and switches the full cooling operation (the flow of the refrigerant indicated with the solid line arrows in Fig. 1) and the full heating operation (the flow of the refrigerant indicated with the broken line arrows in Fig. 1). Note that the control unit 19 may be distributed and disposed in the outdoor unit 5 and the indoor units 6A, 6B,.... For example, the control unit 19 of the outdoor unit 5 controls the inverter circuit 18 and the three switching valves 12A, 12B, and 12C, and the control unit 19 of the respective indoor units 6A, 6B,... controls the corresponding discharge gas pipe shutoff valves 25A, 25B,... and suction gas pipe shutoff valves 26A, 26B,....

[0056] Here, an operation state of the air conditioner 1 will be described. In any operation, the compressor 2 discharges the refrigerant to the first pipe 61 and the second branch pipe 62 and sucks the refrigerant from the eighth branch pipe 68 and the ninth pipe 69.

[0057] The flowing direction of the refrigerant in the full cooling operation is indicated with the solid line arrows in Fig. 1. The second switching valve 12B and the third switching valve 12C are switched so as to connect the discharge side of the compressor 2 to the respective outdoor heat exchangers 13 (31a and 31b). That is, the second branch pipe 62 is connected to the third pipe 63 and the fourth pipe 64. The first switching valve 12A is switched so as to shut off the connection of the discharge side of the compressor 2 and the 10th pipe 70. The discharge gas pipe shutoff valves 25A, 25B,... are fully closed. The suction gas pipe shutoff valves 26A, 26B,... are fully opened and the indoor heat exchangers 21A, 21B,... are connected to the suction side of the compressor 2.

[0058] The compressor 2 discharges a high-temperature and high-pressure gas refrigerant to the first pipe 61. The high-temperature and high-pressure gas refrigerant flows from the first pipe 61 into the oil separator 11. The oil separator 11 separates the refrigerator oil from the high-temperature and high-pressure gas refrigerant. The gas refrigerant from which the oil is separated flows out from the oil separator 11 and reaches the two outdoor heat exchangers 13 (31a and 31b) through the second switching valve 12B and the third switching valve 12C. The two outdoor heat exchangers 13 (31a and 31b) exchange the heat between the outdoor air and the gas refrigerant to condense the refrigerant, and cause the liquid refrigerant to flow out. The liquid refrigerant flowing out from the two outdoor heat exchangers 13 (31a and 31b) reaches the respective indoor heat exchangers 21A, 21B,... through the two outdoor expansion valves 15 (15a and 15b), the 11th pipes 71A, 71B,... inside the respective switching units 7A, 7B,..., and the respective indoor expansion valves 22A, 22B,.... The two outdoor expansion valves 15 (15a and 15b) adjust the flow rate of the liquid refrigerant to adjust a supercooling degree. The respective indoor expansion valves 22A, 22B,... reduce the pressure of the liquid refrigerant to attain a low-pressure gas-liquid two-phase refrigerant. The respective indoor heat exchangers 21A, 21B,... exchange the heat between the indoor air and the gas-liquid two-phase refrigerant to evaporate the refrigerant, and cause the gas refrigerant to flow out. The gas refrigerant flowing out from the respective indoor heat exchangers 21A, 21B,... is sent back to the outdoor unit 5 through the suction gas pipe shutoff valves 26A, 26B,... of the respective switching units 7A, 7B,.... At that time, the discharge gas pipe shutoff valves 25A, 25B,... are fully closed and the flow of the refrigerant in the connecting pipe 36 is blocked. The gas refrigerant that reaches the outdoor unit 5 is sucked into the accumulator 16 through the eighth branch pipe 68. The accumulator 16 separates a small amount of the liquid refrigerant mixed in the gas refrigerant. The gas refrigerant from which the liquid is separated flows out from the accumulator 16 and is sucked into the compressor 2. The sucked gas refrigerant is compressed in the compressor 2 and is discharged again from the compressor 2.

[0059] Next, the flowing direction of the refrigerant in the full heating operation is indicated with the broken line arrows in Fig 1. The refrigerant generally flows in a direction opposite to that in the full cooling operation. The first switching valve 12A is switched so as to connect the discharge side of the compressor 2 and the switching units 7A, 7B,.... That is, the second branch pipe 62 is connected to the 10th pipe 70. The discharge gas pipe shutoff valves 25A, 25B,... are fully opened to connect the discharge side of the compressor 2 and the indoor heat exchangers 21A, 21B,.... The suction gas pipe shutoff valves 26A, 26B,... are fully closed. The second switching valve 12B and the third switching valve 12C are switched so as to connect the two outdoor heat exchangers 13 (31a and 31b) to the suction side of the compressor 2.

[0060] The gas refrigerant from which the oil is separated flows out from the oil separator 11 and reaches the respective switching units 7A, 7B,... through the first switching valve 12A. The gas refrigerant that reaches the respective switching units 7A, 7B,... reaches the respective indoor heat exchangers 21A, 21B,... through the respective discharge gas pipe shutoff valves 25A, 25B,.... At that time, the suction gas pipe shutoff valves 26A, 26B,... are fully closed. The indoor heat exchangers 21A, 21B,... exchange the heat between the indoor air and the gas refrigerant to condense the refrigerant, and cause the liquid refrigerant to flow out. The liquid refrigerant flowing out from the indoor heat exchangers 21A, 21B,... reaches the two outdoor heat exchangers 13 (31a and 31b) through the respective indoor expansion valves 22A, 22B,..., the 11th pipes 71A, 71B,... inside the respective switching units 7A, 7B,..., and the two outdoor expansion valves 15 (15a and 15b). The two outdoor expansion valves 15 (15a and 15b) reduce the pressure of the liquid refrigerant to attain the low-pressure gas-liquid two-phase refrigerant. The two outdoor heat exchangers 13 (31a and 31b) exchange the heat between the outdoor air and the gas-liquid two-phase refrigerant to evaporate the refrigerant, and cause the gas refrigerant to flow out. The gas refrigerant flowing out from the two outdoor heat exchangers 13 (31a and 31b) is sucked into the accumulator 16 through the second switching valve 12B and the third switching valve 12C.

[0061] Fig. 2 is a diagram illustrating a first case of a flow of a refrigerant in a mixed cooling operation state of the air conditioner according to the embodiment of the present invention.

[0062] Fig. 2 illustrates a case of performing the cooling operation in which the two outdoor heat exchangers 13 (31a and 31b) function as condensers and the indoor heat exchangers 21A and 21B function as evaporators and simultaneously performing the heating operation in which the indoor heat exchanger 21C functions as a condenser. The flowing direction of the refrigerant related to the cooling operation is indicated with solid line arrows in Fig. 2, and the flowing direction of the refrigerant related to the heating operation is indicated with broken line arrows in Fig. 2.

[0063] The control unit 19 controls the three switching valves 12A, 12B, and 12C, the plurality of discharge gas pipe shutoff valves 25A, 25B,..., and the plurality of suction gas pipe shutoff valves 26A, 26B,... based on the operation input to the remote controller (not illustrated), and executes the mixed cooling operation in the first case of the air conditioner 1.

[0064] In the case of the mixed cooling operation in the first case, the second switching valve 12B and the third switching valve 12C are switched so as to connect the discharge side of the compressor 2 to the two outdoor heat exchangers 13 (31a and 31b). The first switching valve 12A is switched so as to connect the discharge side of the compressor 2 and the switching units 7A, 7B,.... That is, the discharge side of the compressor 2 is connected to the two outdoor heat exchangers 13 (31a and 31b) and is also connected to the switching units 7A, 7B,... at the same time.

[0065] In the mixed cooling operation in the first case, the switching state of the first switching valve 12A is different as compared to the case of the full cooling operation, and an open / closed state of the discharge gas pipe shutoff valve 25C and the suction gas pipe shutoff valve 26C connected to the indoor heat exchanger 21C that performs the heating operation is inverted.

[0066] The discharge gas pipe shutoff valves 25A and 25B connected to the indoor heat exchangers 21A and 21B that perform the cooling operation are fully closed, and the suction gas pipe shutoff valves 26A and 26B connected to the indoor heat exchangers 21A and 21B that perform the cooling operation are fully opened. The indoor heat exchangers 21A and 21B are connected to the suction side of the compressor 2.

[0067] The discharge gas pipe shutoff valve 25C connected to the indoor heat exchanger 21C that performs the heating operation is fully opened, and the suction gas pipe shutoff valve 26C connected to the indoor heat exchanger 21C that performs the heating operation is fully closed. The indoor heat exchanger 21C is connected to the discharge side of the compressor 2.

[0068] The flow of the refrigerant in the mixed cooling operation in the first case will be described focusing on differences from the flow of the refrigerant in the full cooling operation. A portion of the gas refrigerant from which the oil is separated flows out from the oil separator 11 and reaches the two outdoor heat exchangers 13 (31a and 31b) through the second switching valve 12B and the third switching valve 12C, and a remaining portion of the gas refrigerant from which the oil is separated reaches the discharge gas pipe shutoff valves 25A, 25B,... of the respective switching units 7A, 7B,... through the first switching valve 12A. The fully closed discharge gas pipe shutoff valves 25A and 25B shut off the flow of the refrigerant to the indoor units 6A and 6B, and the fully opened discharge gas pipe shutoff valve 25C allows the flow of the refrigerant to the indoor unit 6C. The indoor heat exchanger 21C exchanges the heat between the indoor air and the gas refrigerant to condense the refrigerant, and causes the liquid refrigerant to flow out. The liquid refrigerant flowing out from the indoor heat exchanger 21C joins the refrigerant flowing into the other indoor heat exchangers 21A and 21B in the connecting pipe 35 through the indoor expansion valve 22C and the 11th pipe 71C inside the switching unit 7C.

[0069] Fig. 3 is a diagram illustrating a second case of the flow of the refrigerant in the mixed cooling operation state of the air conditioner according to the embodiment of the present invention.

[0070] Fig. 3 illustrates a case of performing the cooling operation in which the auxiliary heat exchanger 31b functions as a condenser and the indoor heat exchangers 21A and 21B function as evaporators and simultaneously performing the heating operation in which the indoor heat exchanger 21C functions as a condenser. The flowing direction of the refrigerant related to the cooling operation is indicated with solid line arrows in Fig. 3, and the flowing direction of the refrigerant related to the heating operation is indicated with broken line arrows in Fig. 3.

[0071] The control unit 19 controls the three switching valves 12A, 12B, and 12C, the plurality of discharge gas pipe shutoff valves 25A, 25B,..., and the plurality of suction gas pipe shutoff valves 26A, 26B,... based on the operation input to the remote controller (not illustrated), and executes the mixed cooling operation in the second case of the air conditioner 1.

[0072] In the case of the mixed cooling operation in the second case, the second switching valve 12B is switched so as to shut off the main heat exchanger 31a from the discharge side of the compressor 2 and the third switching valve 12C is switched so as to connect the discharge side of the compressor 2 to the auxiliary heat exchanger 31b.

[0073] The first switching valve 12A is switched so as to connect the discharge side of the compressor 2 and the plurality of switching units 7A, 7B,.... That is, the discharge side of the compressor 2 is connected to the auxiliary heat exchanger 31b and is also connected to the switching units 7A, 7B,... at the same time.

[0074] In the mixed cooling operation in the second case, the switching state of the second switching valve 12B and the first switching valve 12A is different as compared to the case of the full cooling operation, the open / closed state of the first outdoor expansion valve 15a is inverted, and the open / closed state of the discharge gas pipe shutoff valve 25C and the suction gas pipe shutoff valve 26C connected to the indoor heat exchanger 21C that performs the heating operation is inverted.

[0075] The discharge gas pipe shutoff valves 25A and 25B connected to the indoor heat exchangers 21A and 21B that perform the cooling operation are fully closed, and the suction gas pipe shutoff valves 26A and 26B connected to the indoor heat exchangers 21A and 21B that perform the cooling operation are fully opened. The indoor heat exchangers 21A and 21B are connected to the suction side of the compressor 2.

[0076] The discharge gas pipe shutoff valve 25C connected to the indoor heat exchanger 21C that performs the heating operation is fully opened, and the suction gas pipe shutoff valve 26C connected to the indoor heat exchanger 21C that performs the heating operation is fully closed. The indoor heat exchanger 21C is connected to the discharge side of the compressor 2.

[0077] In the mixed cooling operation in the second case, the refrigerant flows generally the same as that in the mixed cooling operation in the first case, however, the second switching valve 12B and the first outdoor expansion valve 15a shut off the flow of the refrigerant to the main heat exchanger 31a.

[0078] Such a mixed cooling operation in the second case is an operation mode advantageous when an outdoor air temperature is close to a target temperature, without requiring refrigerating capacity as compared to the mixed cooling operation in the first case.

[0079] Note that the outdoor unit 5 of the air conditioner 1 that does not perform the mixed cooling operation in the second case and performs the mixed cooling operation in the first case may include at least one outdoor heat exchanger 13 and at least one outdoor expansion valve 15, and may not include the third switching valve 12C connected to the auxiliary heat exchanger 31b.

[0080] Fig. 4 is a diagram illustrating a case of the flow of the refrigerant in the mixed heating operation state of the air conditioner according to the embodiment of the present invention.

[0081] Fig. 4 illustrates a case of the heating operation in which the two outdoor heat exchangers 13 (31a and 31b) function as evaporators and the indoor heat exchangers 21A and 21B function as condensers and the cooling operation in which the indoor heat exchanger 21C functions as an evaporator. The flowing direction of the refrigerant related to the cooling operation is indicated with solid line arrows in Fig. 4, and the flowing direction of the refrigerant related to the heating operation is indicated with broken line arrows in Fig. 4.

[0082] The control unit 19 controls the three switching valves 12A, 12B, and 12C, the plurality of discharge gas pipe shutoff valves 25A, 25B,..., and the plurality of suction gas pipe shutoff valves 26A, 26B,... based on the operation input to the remote controller (not illustrated), and executes the mixed heating operation of the air conditioner 1.

[0083] The switching state of the three switching valves 12A, 12B, and 12C in the mixed heating operation is the same as the switching state of the three switching valves 12A, 12B, and 12C in the full heating operation.

[0084] In the mixed heating operation, the open / closed state of the discharge gas pipe shutoff valve 25C and the suction gas pipe shutoff valve 26C connected to the indoor heat exchanger 21C that performs the cooling operation is inverted as compared to the case of the full heating operation.

[0085] The discharge gas pipe shutoff valves 25A and 25B connected to the indoor heat exchangers 21A and 21B that perform the heating operation are fully opened, and the suction gas pipe shutoff valves 26A and 26B connected to the indoor heat exchangers 21A and 21B that perform the heating operation are fully closed. That is, the indoor heat exchangers 21A and 21B are connected to the discharge side of the compressor 2.

[0086] The discharge gas pipe shutoff valve 25C connected to the indoor heat exchanger 21C that performs the cooling operation is fully closed, and the suction gas pipe shutoff valve 26C connected to the indoor heat exchanger 21C that performs the cooling operation is fully opened. That is, the indoor heat exchanger 21C is connected to the suction side of the compressor 2.

[0087] In the mixed heating operation, the refrigerant flows generally the same as that in the full heating operation, however, the liquid refrigerant flowing out from the indoor heat exchangers 21A and 21B is branched in the connecting pipe 35, is subjected to pressure reduction in the indoor expansion valve 22C, and reaches the indoor heat exchanger 21C. The indoor heat exchanger 21C exchanges the heat between the indoor air and the gas-liquid two-phase refrigerant to evaporate the refrigerant, and causes the gas refrigerant to flow out. The gas refrigerant flowing out from the indoor heat exchanger 21C is sucked into the accumulator 16 through the suction gas pipe shutoff valve 26C.

[0088] Fig. 5 is a block diagram of a second form of the air conditioner according to the embodiment of the present invention.

[0089] As illustrated in Fig. 5, the air conditioner 1 according to the present embodiment may not include the plurality of switching units 7A, 7B,.... The connecting pipe 35 connects one pipe connecting part 41 of the outdoor unit 5 and the respective pipe connecting parts 51A, 51B,... of the plurality of indoor units 6A, 6B,.... The connecting pipe 36 connects one pipe connecting part 42 of the outdoor unit 5 and the respective pipe connecting parts 52A, 52B,... of the plurality of indoor units 6A, 6B,.... The connecting pipe 37 is not needed, and the pipe connecting part 43 is maintained in a closed state. The first switching valve 12A of the outdoor unit 5 is switched such that the refrigerant is sucked from the plurality of indoor units 6A, 6B,... to the compressor 2 during the cooling operation and the refrigerant is sent from the compressor 2 to the plurality of indoor units 6A, 6B,... during the heating operation.

[0090] The air conditioner 1 may include a sealing plug 81 that closes the pipe connecting part 43 of the outdoor unit 5 and that is indicated in Fig. 5 with a two-dot chain line.

[0091] That is, the air conditioner 1 can be utilized in the second form in which the pipe connecting part 43 is closed, the plurality of switching units 7A, 7B,... and the connecting pipe 37 are not provided, and the outdoor unit 5 and the plurality of indoor units 6A, 6B,... are directly connected by the connecting pipes 35 and 36. The air conditioner 1 in the second form performs the cooling operation by circulating the refrigerant in a direction indicated with solid line arrows in Fig. 5, and performs heating by circulating the refrigerant in a direction indicated with broken line arrows in Fig. 5.

[0092] When the full cooling operation is performed in the air conditioner 1 in the second form, the second switching valve 12B is switched so as to connect the discharge side of the compressor 2 and the outdoor heat exchanger 13 and to shut off the eighth branch pipe 68 (an outdoor third pipe) and the discharge side of the compressor 2. The first switching valve 12A is switched so as to connect the 10th pipe 70 (an outdoor second pipe) and the eighth branch pipe 68 on the suction side of the compressor 2.

[0093] When the full heating operation is performed in the air conditioner 1 in the second form, the first switching valve 12A is switched so as to connect the discharge side of the compressor 2 and the 10th pipe 70 and to shut off the eighth branch pipe 68 and the discharge side of the compressor 2. The second switching valve 12B is switched so as to connect the outdoor heat exchanger 13 and the suction side of the compressor 2.

[0094] Thus, when the pipe connecting part 43 of the outdoor unit 5 is closed, the air conditioner 1 functions as a multi-type air conditioner that performs the full cooling operation or the full heating operation.

[0095] Note that there may be only one system of the outdoor heat exchanger 13 for Fig. 1 to Fig. 5. For example, the outdoor unit 5 only needs to include the main heat exchanger 31a. In this case, the third switching valve 12C, the auxiliary heat exchanger 31b, and the second outdoor expansion valve 15b are not needed.

[0096] Fig. 6 is a schematic diagram of a comparative example of the eighth branch pipe of the outdoor unit according to the embodiment of the present invention.

[0097] Fig. 7 is a schematic diagram of a first example of the eighth branch pipe of the outdoor unit according to the embodiment of the present invention.

[0098] As illustrated in Fig. 5 and Fig. 6, the comparative example of the eighth branch pipe 68 connects the three switching valves 12A, 12B, and 12C and the accumulator 16 disposed on the suction side of the compressor 2, and also connects the pipe connecting part 43 and the accumulator 16. That is, the eighth branch pipe 68 is the refrigerant piping 8 connected to the suction side of the compressor 2 regardless of the operation state of the air conditioner 1. The eighth branch pipe 68 includes a branch portion D where pipes to the first switching valve 12A, the accumulator 16, and the pipe connecting part 43 intersect.

[0099] In the air conditioner 1 in the second form, the eighth branch pipe 68 is not connected to the connecting pipe 37. In other words, a pipe between the branch portion D and the pipe connecting part 43 becomes a so-called blind alley DE in the air conditioner 1 in the second form. There is a risk that the refrigerant and the refrigerator oil mixed in the refrigerant stay in the blind alley DE.

[0100] For the flow of the refrigerant and the refrigerator oil mixed in the refrigerant inside the eighth branch pipe 68, the flow during the cooling operation is indicated with outline arrows with solid line, the flow during the heating operation is indicated with black arrows, and the flow in common for the cooling operation and the heating operation is indicated with a hatched arrow. The refrigerant during the cooling operation flows from the first switching valve 12A into the eighth branch pipe 68, and the refrigerant during the heating operation flows from the second switching valve 12B and the third switching valve 12C into the eighth branch pipe 68. In addition, the refrigerant and the refrigerator oil mixed in the refrigerant staying in the blind alley DE are indicated by a hatched region FS.

[0101] Then, as illustrated in Fig. 7, an eighth branch pipe 68A of the first example of the outdoor unit 5 according to the present embodiment includes a main flow pipe portion 85 through which the refrigerant to be sucked into the compressor 2 through the first switching valve 12A in one switching state of the first switching valve 12A or the refrigerant to be sucked into the compressor 2 through the second switching valve 12B and the third switching valve 12C in one switching state of the second switching valve 12B and the third switching valve 12C flows, and a trap portion 86 that intersects the main flow pipe portion 85, branches upwards and then goes downwards.

[0102] When the air conditioner is performing the cooling operation, the refrigerant is sucked into the compressor 2 through the first switching valve 12A. That is, one switching state of the first switching valve 12A in which the refrigerant to be sucked into the compressor 2 through the first switching valve 12A flows through the main flow pipe portion 85 corresponds to the switching state of the first switching valve 12A in the full cooling operation of the air conditioner 1. Further, when the air conditioner is performing the heating operation, the refrigerant is sucked into the compressor 2 through the second switching valve 12B and the third switching valve 12C. That is, one switching state of the first switching valve 12A in which the refrigerant to be sucked into the compressor 2 through the second switching valve 12B and the third switching valve 12C flows through the main flow pipe portion 85 corresponds to the switching state of the second switching valve 12B and the third switching valve 12C in the full heating operation of the air conditioner 1.

[0103] The main flow pipe portion 85 has an upstream straight pipe portion 85u that sends the refrigerant from the three switching valves 12A, 12B, and 12C to the branch portion D.

[0104] In addition, the main flow pipe portion 85 has a downstream straight pipe portion 85d that extends vertically downwards from the branch portion D of the main flow pipe portion 85 and the trap portion 86 such that liquid contained in the refrigerant flows vertically downwards. The downstream straight pipe portion 85d is a part of the eighth branch pipe 68A that connects the branch portion D and the accumulator 16.

[0105] The trap portion 86 has a straight pipe portion 86a that extends vertically upwards from the branch portion D. The straight pipe portion 86a is a part of the eighth branch pipe 68A that connects the branch portion D and the pipe connecting part 43, and is connected to a bent portion 86b at a position separated from the branch portion D. The eighth branch pipe 68A after the bent portion 86b extends further downwards and preferably reaches the pipe connecting part 43 below the upstream straight pipe portion 85u of the main flow pipe portion 85. A part of the eighth branch pipe 68A that connects the branch portion D and the pipe connecting part 43 is the blind alley DE. That is, the straight pipe portion 86a, the bent portion 86b, and a part of the eighth branch pipe 68A that connects the bent portion 86b and the pipe connecting part 43 are the blind alley DE.

[0106] It is preferable that the upstream straight pipe portion 85u and the straight pipe portion 86a of the trap portion 86 branch off and intersect forming an angle θ1 smaller than or equal to 90 degrees. It is preferable that the upstream straight pipe portion 85u and the downstream straight pipe portion 85d branch off and intersect forming an angle θ2 larger than or equal to 90 degrees. Further, the downstream straight pipe portion 85d and the straight pipe portion 86a of the trap portion 86 are preferably one continuous straight pipe. As one example, a shape of the branch portion D is a lying T shape formed by the downstream straight pipe portion 85d and the straight pipe portion 86a of the trap portion 86 as one continuous straight pipe extending in a vertical direction and the upstream straight pipe portion 85u that collides with the continuous straight pipe from a horizontal direction.

[0107] During the cooling operation, the refrigerant flowing to the eighth branch pipe 68A illustrated in Fig. 7 flows in from the first switching valve 12A, reaches the branch portion D from the upstream straight pipe portion 85u, and flows down so as to be drawn into the downstream straight pipe portion 85d by gravity and a suction pressure of the compressor 2. Similarly, during the heating operation, the refrigerant flowing to the eighth branch pipe 68A flows in from the second switching valve 12B and the third switching valve 12C, reaches the branch portion D from the upstream straight pipe portion 85u, and flows down so as to be drawn into the downstream straight pipe portion 85d by the gravity and the suction pressure of the compressor 2. Further, the refrigerant that has reached the branch portion D from the upstream straight pipe portion 85u hits an inner wall surface of the downstream straight pipe portion 85d and the straight pipe portion 86a of the trap portion 86, stagnates, slows down, and flows down so as to be drawn into the downstream straight pipe portion 85d by the gravity and the suction pressure of the compressor 2. At that time, a small amount of the refrigerant is to go upwards in the branch portion D, however, it is blocked by the trap portion 86 including the straight pipe portion 86a that extends upwards, and since the blind alley DE is after the trap portion 86, the risk that the refrigerant and the refrigerator oil stay in the blind alley DE is reduced.

[0108] Fig. 8 is a schematic diagram of a second example of the eighth branch pipe of the outdoor unit according to the embodiment of the present invention.

[0109] As illustrated in Fig. 8, for an eighth branch pipe 68B of the second example of the outdoor unit 5 according to the present embodiment, the upstream straight pipe portion 85u and the downstream straight pipe portion 85d of the main flow pipe portion 85 are continuously provided vertically downwards in a straight pipe shape, and the trap portion 86 branches off in the horizontal direction from the branch portion D in the middle.

[0110] Since the upstream straight pipe portion 85u and the downstream straight pipe portion 85d of the main flow pipe portion 85 are continuously provided vertically downwards in the straight pipe shape, the refrigerant that flows into the upstream straight pipe portion 85u easily flows straight down through the downstream straight pipe portion 85d. At that time, a small amount of the refrigerant is to flow from the branch portion D to the trap portion 86, however, it is blocked by the flow of the refrigerant flowing through the main flow pipe portion 85 in a vertically downward straight pipe shape, and since the blind alley DE is after the trap portion 86, the risk that the refrigerant and the refrigerator oil stay in the blind alley DE is reduced.

[0111] Fig. 9 is a schematic diagram of a third example of the eighth branch pipe of the outdoor unit according to the embodiment of the present invention.

[0112] As illustrated in Fig. 9, an eighth branch pipe 68C of the third example of the outdoor unit 5 according to the present embodiment has the branch portion D in an inverted T shape.

[0113] The upstream straight pipe portion 85u and the downstream straight pipe portion 85d of the main flow pipe portion 85 continue in the horizontal direction in the straight pipe shape. The main flow pipe portion 85 and the straight pipe portion 86a of the trap portion 86 intersect. That is, the shape of the branch portion D is the inverted T shape formed by the main flow pipe portion 85 that extends in the horizontal direction and the straight pipe portion 86a of the trap portion 86 that intersects the main flow pipe portion 85, branches off, and extends in the vertical direction.

[0114] The refrigerant flowing to the eighth branch pipe 68C illustrated in Fig. 9 reaches the branch portion D from the upstream straight pipe portion 85u, and advances straight so as to be drawn into the downstream straight pipe portion 85d by inertial force and the suction pressure of the compressor 2. At that time, a small amount of the refrigerant is to flow upwards in the branch portion D, however, it is blocked by the trap portion 86 including the straight pipe portion 86a that extends upwards, and since the blind alley DE is after the trap portion 86, the risk that the refrigerant and the refrigerator oil stay in the blind alley DE is reduced.

[0115] Fig. 10 is a schematic diagram of a fourth example of the eighth branch pipe of the outdoor unit according to the embodiment of the present invention.

[0116] As illustrated in Fig. 10, an eighth branch pipe 68D of the fourth example of the outdoor unit 5 according to the present embodiment includes a first branch portion D and a second branch portion D'.

[0117] The eighth branch pipe 68D of the fourth example includes the second branch portion D' in the middle of the vertically downward straight pipe portion 86a that extends to the pipe connecting part 43 of the trap portion 86 in the eighth branch pipe 68A of the first example. A second main flow pipe portion 85' through which the refrigerant to be sucked into the compressor 2 through the first switching valve 12A flows is connected to the second branch portion D'.

[0118] When the air conditioner is performing the cooling operation, the refrigerant is sucked into the compressor 2 through the first switching valve 12A. That is, one switching state of the first switching valve 12A in which the refrigerant to be sucked into the compressor 2 through the first switching valve 12A flows through the second main flow pipe portion 85' corresponds to the switching state of the first switching valve 12A in the full cooling operation of the air conditioner 1.

[0119] The second main flow pipe portion 85' includes a second upstream straight pipe portion 85'u that sends the refrigerant from the first switching valve 12A into the second branch portion D'.

[0120] The second upstream straight pipe portion 85'u passes through the second branch portion D' and the trap portion 86, joins the first branch portion D at the first branch portion D, and is connected to the downstream straight pipe portion 85d.

[0121] It is preferable that the second upstream straight pipe portion 85'u and the straight pipe portion 86a of the trap portion 86 branch off and intersect forming an angle θ'2 larger than or equal to 90 degrees. It is preferable that the second upstream straight pipe portion 85'u and the straight pipe portion 86a that extends to the pipe connecting part 43 branch off and intersect forming an angle 8'1 smaller than or equal to 90 degrees. As one example, a shape of the second branch portion D' is a lying T shape formed by the straight pipe portion 86a of the trap portion 86 that extends to the pipe connecting part 43 as one continuous straight pipe extending in the vertical direction and the second upstream straight pipe portion 85'u that collides with the straight pipe from the horizontal direction.

[0122] The eighth branch pipe 68D of the fourth example is the same as the configuration of the eighth branch pipe 68A of the first example except for the configuration that the second branch portion D', the second main flow pipe portion 85', and the second upstream straight pipe portion 85'u are provided and the first switching valve 12A is connected to the second main flow pipe portion 85', and the detailed description of the same part will be omitted.

[0123] The refrigerant flowing to the eighth branch pipe 68D during the cooling operation reaches the second branch portion D' from the second upstream straight pipe portion 85'u, is drawn into the trap portion 86 by the suction pressure of the compressor 2, and after passing through the trap portion 86, flows down so as to be pulled into the downstream straight pipe portion 85d by the gravity and the suction pressure of the compressor 2. At that time, a small amount of the refrigerant flows downwards through the second branch portion D' and there is the risk that the refrigerant and the refrigerator oil stay. However, the refrigerant flowing into the eighth branch pipe 68D from the second switching valve 12B and the third switching valve 12C during the heating operation is blocked by the trap portion 86 including the straight pipe portion 86a that extends upwards, and since the blind alley DE is after the trap portion 86, the risk that the refrigerant and the refrigerator oil stay in the blind alley DE is reduced as compared to the comparative example illustrated in Fig 6.

[0124] Fig. 11 is a block diagram of a third form of the air conditioner according to the embodiment of the present invention.

[0125] As illustrated in Fig. 11, the outdoor unit 5 of the air conditioner 1 according to the present embodiment may include a recovery pipe 101 connected to the pipe connecting part 43 and the suction side of the accumulator 16. The recovery pipe 101 directly connects the blind alley DE of each of the eighth branch pipes 68, 68A, 68B, 68C, and 68D to a vicinity of the accumulator 16 connected to each of the eighth branch pipes 68, 68A, 68B, 68C, and 68D, and recovers the refrigerant and the refrigerator oil staying in the blind alley DE to the compressor 2. That is, the recovery pipe 101 directly connects the blind alley DE to the vicinity of the accumulator 16 so as to make a detour around the branch portion of the eighth branch pipes 68, 68A, 68B, 68C, and 68D, which is the branch portion to the three switching valves 12A, 12B, and 12C.

[0126] The eighth branch pipes 68A, 68B, 68C, and 68D of the first example to the fourth example have a pipe structure that suppresses congestion of the refrigerant and the refrigerator oil in the blind alley DE to begin with. Therefore, the amount of the refrigerant and the refrigerator oil that can stay in the blind alley DE is not large. However, as long as the flow occurs in the main flow pipe portion 85, it is difficult to completely block invasion of the refrigerant and the refrigerator oil to the blind alley DE. The recovery pipe 101 completely dissolves the congestion of a fine amount of the refrigerant and the refrigerator oil in the blind alley DE.

[0127] As described above, the outdoor unit 5 according to the present embodiment includes: the first switching valve 12A capable of shutting off the connection of the discharge side of the compressor 2 and the indoor heat exchangers 21A, 21B,... of all of the indoor units 6A, 6B,... to cause the outdoor heat exchanger 13 to function as a condenser or connecting the discharge side of the compressor 2 to the indoor heat exchangers 21A, 21B,... of at least one of the indoor units 6A, 6B,... to cause the indoor heat exchangers 21A, 21B,... of at least one of the indoor units 6A, 6B,... to function as a condenser; and the second switching valve 12B capable of connecting the discharge side of the compressor 2 to the outdoor heat exchanger 13 to cause the outdoor heat exchanger 13 to function as a condenser or connecting the suction side of the compressor 2 to the outdoor heat exchanger 13 to cause the outdoor heat exchanger 13 to function as an evaporator. In addition, the outdoor unit 5 includes: the seventh branch pipe 67 as an outdoor first pipe that connects the outdoor heat exchanger 13 and the indoor units 6A, 6B,...; the 10th pipe 70 as the outdoor second pipe that is one of branches of the first switching valve 12A and connects the compressor 2 and the indoor units 6A, 6B,...; and the eighth branch pipe 68A, 68B, 68C, or 68D as the outdoor third pipe that is connected to one of the branches of the first switching valve 12A and connects the compressor 2 and the indoor units 6A, 6B,... making a detour around the first switching valve 12A.

[0128] Then, the eighth branch pipe 68A, 68B, 68C, or 68D includes the main flow pipe portion 85 through which the refrigerant to be sucked into the compressor 2 through the first switching valve 12A in one switching state of the first switching valve 12A flows, and the trap portion 86 that intersects the main flow pipe portion 85 and then goes downwards. Therefore, the air conditioner 1 and the outdoor unit 5 can reduce the risk that the refrigerant and the refrigerator oil stay in a part of the refrigerant piping 8 to be the blind alley DE in the second form.

[0129] Further, the outdoor unit 5 according to the present embodiment includes: the first switching valve 12A capable of shutting off the connection of the discharge side of the compressor 2 and the indoor heat exchangers 21A, 21B,... of all of the indoor units 6A, 6B,... to cause the outdoor heat exchanger 13 to function as a condenser or connecting the discharge side of the compressor 2 to the indoor heat exchangers 21A, 21B,... of at least one of the indoor units 6A, 6B,... to cause the indoor heat exchangers 21A, 21B,... of at least one of the indoor units 6A, 6B,... to function as a condenser; and the second switching valve 12B capable of connecting the discharge side of the compressor 2 to the outdoor heat exchanger 13 to cause the outdoor heat exchanger 13 to function as a condenser or connecting the suction side of the compressor 2 to the outdoor heat exchanger 13 to cause the outdoor heat exchanger 13 to function as an evaporator. In addition, the outdoor unit 5 includes: the seventh branch pipe 67 as the outdoor first pipe that connects the outdoor heat exchanger 13 and the indoor units 6A, 6B,...; the 10th pipe 70 as the outdoor second pipe that is one of the branches of the first switching valve 12A and connects the compressor 2 and the indoor units 6A, 6B,...; and the eighth branch pipe 68A, 68B, 68C, or 68D as the outdoor third pipe that is connected to one of the branches of the first switching valve 12A and is connected to the compressor 2. When connecting the seventh branch pipe 67, the 10th pipe 70, and the eighth branch pipe 68A, 68B, 68C, or 68D to the indoor units 6A, 6B,... via the plurality of switching units 7A, 7B,... capable of switching the flowing direction of the refrigerant flowing to the indoor units 6A, 6B,..., the eighth branch pipe 68A, 68B, 68C, or 68D connects the compressor 2 and the indoor units 6A, 6B,... making a detour around the first switching valve 12A.

[0130] Then, when connecting the seventh branch pipe 67 and the 10th pipe 70 to the indoor units 6A, 6B,... without interposing the plurality of switching units, the eighth branch pipe 68A, 68B, 68C, or 68D includes the main flow pipe portion 85 through which the refrigerant to be sucked into the compressor 2 through the first switching valve 12A in one switching state of the first switching valve 12A flows, and the trap portion 86 that intersects the main flow pipe portion 85 and then goes downwards. Therefore, the air conditioner 1 and the outdoor unit 5 can reduce the risk that the refrigerant and the refrigerator oil stay in a part of the refrigerant piping 8 to be the blind alley DE in the second form.

[0131] Further, the outdoor unit 5 according to the present embodiment includes the downstream straight pipe portion 85d that extends vertically downwards from the branch portion D of the main flow pipe portion 85 and the trap portion 86 such that the liquid contained in the refrigerant flows vertically downwards. Therefore, the air conditioner 1 and the outdoor unit 5 can reduce the risk that the refrigerant and the refrigerator oil stay in a part to be the blind alley DE in the second form, and can smoothly return the liquid contained in the refrigerant to the compressor 2.

[0132] Further, the outdoor unit 5 according to the present embodiment includes the recovery pipe 101 that connects the eighth branch pipe 68, 68A, 68B, 68C, or 68D to the suction side of the compressor 2. Therefore, the air conditioner 1 and the outdoor unit 5 can completely dissolve the congestion of a fine amount of the refrigerant and the refrigerator oil in the blind alley DE.

[0133] Then, the air conditioner 1 according to the present embodiment includes the outdoor unit 5, the plurality of indoor units 6A, 6B,..., and the plurality of switching units 7A, 7B,.... The air conditioner 1 including the plurality of switching units 7A, 7B,... can cause the flowing direction of the refrigerant flowing to the plurality of indoor units 6A, 6B,... to be different from each other to mix the indoor units 6A, 6B,... that perform the cooling operation and the indoor units 6A, 6B,... that perform the heating operation. The air conditioner 1 according to the present embodiment may include the outdoor unit 5 and the plurality of indoor units 6A, 6B,... and have one of branches of the first switching valve 12A closed. The air conditioner 1 which does not include the plurality of switching units 7A, 7B, ... and has one of the branches of the first switching valve 12A closed unifies the flowing direction of the refrigerant flowing to the plurality of indoor units 6A, 6B,... to cause all of the indoor units 6A, 6B,... to perform the cooling operation or the heating operation. That is, the air conditioner 1 can function as a heat-recovery multi-type air conditioner by selecting the plurality of switching units 7A, 7B,..., and function as a multi-type air conditioner by selecting non-application of the plurality of switching units 7A, 7B,....

[0134] Thus, the air conditioner 1 and the outdoor unit 5 of the air conditioner 1 according to the present embodiment are applicable to both of a heat recovery type and a general multi-type and are capable of suppressing the congestion of the refrigerator oil in the eighth branch pipe 68, 68A, 68B, 68C, or 68D that is closed when applied to the multi-type.

[0135] While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions, and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.REFERENCE SIGNS LIST

[0136] 1...air conditioner, 2...compressor, 2a...accumulator, 5...outdoor unit, 6A, 6B, 6C...indoor unit, 7A, 7B, 7C...switching unit, 8... refrigerant piping, 11... oil separator, 12A...first switching valve, 12B...second switching valve, 12C...third switching valve, 13...outdoor heat exchanger, 15, 15a, 15b...outdoor expansion valve, 16...accumulator, 17...outdoor fan, 18...inverter circuit, 19...control unit, 21A, 21B, 21C...indoor heat exchanger, 22A, 22B, 22C... indoor expansion valve, 23A, 23B, 23C...indoor fan, 25A, 25B, 25C...discharge gas pipe shutoff valve, 26A, 26B, 26C...suction gas pipe shutoff valve, 28...path, 29...header, 31a...main heat exchanger, 31b...auxiliary heat exchanger, 35, 36, 37, 38A, 38B, 38C, 39A, 39B, 39C...connecting pipe, 41, 42, 43...pipe connecting part of outdoor unit, 45A, 45B, 45C, 46A, 46B, 46C, 47A, 47B, 47C...pipe connecting part on outdoor unit side of switching unit, 48A, 48B, 48C, 49A, 49B, 49C...pipe connecting part on indoor unit side of switching unit, 51A, 51B, 51C, 52A, 52B, 52C...pipe connecting part of indoor unit, 61...first pipe, 62...second branch pipe, 63...third pipe, 64...fourth pipe, 65...fifth pipe, 66... sixth pipe, 67...seventh branch pipe, 68, 68A, 68C, 68D...eighth branch pipe, 69...ninth pipe, 70...10th pipe, 71A, 71B, 71C...11th pipe, 72A, 72B, 72C...12th branch pipe, 73A, 73B, 73C...13th pipe, 74A, 74B, 74C...14th pipe, 75A, 75B, 75C...15th pipe, 76A, 76B, 76C...16th pipe, 77A, 77B, 77C...17th pipe, 81...sealing plug, 85...main flow pipe portion, 85'...second main flow pipe portion, 85u...upstream straight pipe portion, 85'u...second upstream straight pipe portion, 85d...downstream straight pipe portion, 86...trap portion, 86a...straight pipe portion, 86b...bent portion, 88...gas-liquid separation unit, 101...recovery pipe.

Claims

1. An outdoor unit of an air conditioner, the outdoor unit comprising: a compressor that compresses a refrigerant; an outdoor heat exchanger that exchanges heat between the refrigerant and outdoor air; a first switching valve that shuts off connection of a discharge side of the compressor and indoor heat exchangers of all of indoor units to cause the outdoor heat exchanger to function as a condenser, or connects the discharge side of the compressor to the indoor heat exchanger of at least one of the indoor units to cause the indoor heat exchanger of the at least one of the indoor units to function as a condenser; a second switching valve that connects the discharge side of the compressor to the outdoor heat exchanger to cause the outdoor heat exchanger to function as a condenser, or connects a suction side of the compressor to the outdoor heat exchanger to cause the outdoor heat exchanger to function as an evaporator; an outdoor first pipe that connects the outdoor heat exchanger and the indoor units; an outdoor second pipe that is one of branches of the first switching valve and connects the compressor and the indoor units; and an outdoor third pipe that is connected to one of the branches of the first switching valve and makes a detour around the first switching valve to connect the compressor and the indoor units, wherein the outdoor third pipe includes a main flow pipe portion through which the refrigerant to be sucked into the compressor through the first switching valve flows and a trap portion that intersects the main flow pipe portion, branches off, and then goes downwards.

2. An outdoor unit of an air conditioner, the outdoor unit comprising: a compressor that compresses a refrigerant; an outdoor heat exchanger that exchanges heat between the refrigerant and outdoor air; a first switching valve that shuts off connection of a discharge side of the compressor and indoor heat exchangers of all of indoor units to cause the outdoor heat exchanger to function as a condenser, or connects the discharge side of the compressor to the indoor heat exchanger of at least one of the indoor units to cause the indoor heat exchanger of the at least one of the indoor units to function as a condenser; a second switching valve that connects the discharge side of the compressor to the outdoor heat exchanger to cause the outdoor heat exchanger to function as a condenser, or connects a suction side of the compressor to the outdoor heat exchanger to cause the outdoor heat exchanger to function as an evaporator; an outdoor first pipe that connects the outdoor heat exchanger and the indoor units; an outdoor second pipe that is one of branches of the first switching valve and connects the compressor and the indoor units; and an outdoor third pipe that is connected to one of the branches of the first switching valve and is connected to the compressor, wherein the outdoor third pipe makes a detour around the first switching valve to connect the compressor and the indoor units when the outdoor first pipe, the outdoor second pipe, and the outdoor third pipe are connected to the indoor units via a plurality of switching units that switch a flowing direction of the refrigerant flowing to the indoor units, and the outdoor third pipe includes a main flow pipe portion through which the refrigerant to be sucked into the compressor through the first switching valve flows and a trap portion that intersects the main flow pipe portion, branches off, and then goes downwards when the outdoor first pipe and the outdoor second pipe are connected to the indoor units without interposing the plurality of switching units.

3. The outdoor unit of the air conditioner according to claim 1 or 2, wherein the main flow pipe portion includes a straight pipe portion that extends vertically downwards from a branch portion of the main flow pipe portion and the trap portion such that liquid contained in the refrigerant flows vertically downwards.

4. The outdoor unit of the air conditioner according to any one of claims 1 to 3, comprising a recovery pipe that connects the outdoor third pipe to the suction side of the compressor.

5. An air conditioner comprising: the outdoor unit according to any one of claims 1 to 4; and a plurality of indoor units that exchange heat between the refrigerant and indoor air, wherein the outdoor unit includes an outdoor expansion valve connected to a discharge side of the outdoor heat exchanger, the indoor units each include an indoor heat exchanger and an indoor expansion valve connected to the indoor heat exchanger, flowing directions of the refrigerant flowing to the plurality of the indoor units are caused to be different from each other to mix the indoor units that perform a cooling operation and the indoor units that perform a heating operation when a plurality of switching units that switch a flowing direction of the refrigerant flowing to the corresponding indoor units are provided, and the flowing directions of the refrigerant flowing to the plurality of the indoor units are unified so as to cause the refrigerant to be sucked into the compressor through the first switching valve during the cooling operation and to cause the refrigerant to be sent to the plurality of the indoor units through the first switching valve during the heating operation, and all of the indoor units are caused to perform the cooling operation or the heating operation when the plurality of switching units are not provided.

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