WO2008047784A1

WO2008047784A1 - Air conditioner

Info

Publication number: WO2008047784A1
Application number: PCT/JP2007/070152
Authority: WO
Inventors: Satoshi Kawano; Shinya Matsuoka; Akihiro Eguchi; Shigeki Kamitani
Original assignee: Daikin Industries, Ltd.
Priority date: 2006-10-17
Filing date: 2007-10-16
Publication date: 2008-04-24
Also published as: JP2008101787A

Abstract

An air conditioner in which, to switch each indoor heat exchanger (41) from cooling operation to heating operation, a controller (50) slightly opens a first control valve (31) after closing a second control valve (32) and then fully opens the first control valve (31) after a utilization-side heat exchanger (41) is equalized in pressure with high-pressure gas piping (11). Also, to switch each indoor heat exchanger (41) from heating operation to cooling operation, the controller (50) slightly opens the second control valve (32) after closing the first control valve (31) and then fully opens the second control valve (32) after the utilization-side heat exchanger (41) is equalized in pressure with low-pressure gas piping (12).

Description

Specification

Air conditioner

Technical field

TECHNICAL FIELD [0001] The present invention relates to an air conditioner, and particularly relates to prevention of noise of refrigerant passing sound that occurs when switching between cooling and heating operations.

Background art

Conventionally, various control valves such as an electromagnetic valve for blocking refrigerant flow and a check valve for allowing refrigerant flow only in one direction are provided in a refrigerant circuit such as an air conditioner. For example, the air conditioner of Patent Document 1 includes an outdoor unit and a plurality of indoor units. A BS unit is connected between the outdoor unit and each indoor unit as an intermediate unit for switching the refrigerant flow path.

[0003] The BS unit has a refrigerant piping structure provided with a plurality of on-off valves and the like.

In this BS unit, the refrigerant evaporated in the indoor unit flows in and flows out toward the compressor of the outdoor unit, and the refrigerant discharged from the compressor of the outdoor unit flows in by switching each on-off valve. Then, it is configured to switch to a state of flowing out toward the indoor unit. Thereby, the cooling operation and the heating operation are individually switched for each indoor unit.

Patent Document 1: JP-A-11 241844

Disclosure of the invention

Problems to be solved by the invention

[0004] By the way, in this type of air conditioner, when switching between cooling and heating of any of the indoor units, pressure equalization control is once performed in order to suppress refrigerant passing noise. In other words, for example, when switching from the cooling operation to the heating operation, if the solenoid valve of the BS unit is switched, the high-pressure refrigerant suddenly flows into the indoor unit that was in the low-pressure state. ) Is prevented by pressure equalization control.

[0005] Here, the pressure equalization control at the time of switching from the cooling operation to the heating operation will be described in Patent Document 1! During cooling operation, the first on-off valve in Fig. 5 of Patent Document 1 is closed. The second on-off valve is open. In the pressure equalization control, first, the second on-off valve is closed to reduce the refrigerant circulation rate. Subsequently, the first on-off valve is opened and the indoor electric expansion valve in FIG. 4 of Patent Document 1 is closed to change the indoor unit from the low pressure state to the high pressure state. When the indoor unit is in a high pressure state (equal pressure state), the indoor electric expansion valve is opened and the heating operation is performed. Thus, since the indoor unit is in a high pressure state in advance, the rapid flow of the high-pressure refrigerant into the indoor unit is suppressed, and the generation of refrigerant passing sound is prevented.

[0006] However, in the conventional air conditioner, when performing the pressure equalization control, all the indoor units are temporarily switched to the cooling operation, so that the heating operation not related to the switching is being performed. The indoor unit is temporarily switched to the cooling operation, so that the heating capacity of the indoor unit becomes zero, and the air conditioning performance as a whole of the air conditioner deteriorates.

[0007] The present invention has been made in view of the power and the point, and the object of the present invention is to improve the air conditioning performance of the air conditioner as a whole while preventing the passage of refrigerant that occurs when switching between cooling and heating operations. Is to ensure.

Means for solving the problem

[0008] A first invention includes a high-pressure gas pipe (11), a low-pressure gas pipe (12), a liquid pipe (13), and a plurality of usage-side heat exchangers (41), and each of the usage-side heat exchanges One end of the vessel (41) is connected to the liquid pipe (13) via an expansion mechanism (42), and the other end is connected to the high-pressure gas pipe (11) via a switching mechanism (30A, 30B). The air conditioner is connected to the low-pressure gas pipe (12) so as to be switchable, and each use-side heat exchanger (41) can be individually operated for cooling and heating.

[0009] The switching mechanism (30A, 30B) has a first control valve (31) whose opening degree is adjustable, and connects the use side heat exchanger (41) and the high pressure gas pipe (11). A high-pressure passage (38), a second control valve (32) whose opening degree is freely adjustable, and a low-pressure passage (39) connecting the use side heat exchanger (41) and the low-pressure gas pipe (12); It is equipped with

[0010] When the switching mechanism (30A, 30B) is switched from the cooling operation to the heating operation, the first control valve (31) is slightly opened after the second control valve (32) is closed, Thereafter, when the first control valve (31) is fully opened to open the high-pressure passage (38) while switching from the heating operation to the cooling operation, the second control is performed after the first control valve (31) is closed. Fine valve (32) Then, the second control valve (32) is fully opened, and the low pressure passage (39) is opened.

[0011] In the first invention, the switching mechanism (30A, 30B) causes the first control valve (31) to be slightly opened after the second control valve (32) is closed, and the use side heat exchanger ( After the pressure is equalized with the high-pressure gas pipe (11), the first control valve (31) is fully opened, and the cooling operation force is switched to the heating operation. On the other hand, after the first control valve (31) is closed by the switching mechanism (30A, 30B), the second control valve (32) is slightly opened, and the use side heat exchanger (41) is connected to the low-pressure gas pipe. After equalizing pressure with (12), the second control valve (32) is fully opened and switched from heating operation to cooling operation.

Therefore, for example, when switching from the cooling operation to the heating operation, the first control valve (31) is slightly opened, and a small amount of high-pressure refrigerant is supplied to the use-side heat exchanger (41) that was in the low-pressure state. Introduced one by one, gradually changing the pressure of the use side heat exchanger (41) from the low pressure state to the high pressure state and equalizing the pressure to the high pressure gas pipe (11), the high pressure refrigerant suddenly increases with respect to the use side heat exchanger (41). It is possible to prevent the refrigerant from passing through and to prevent the passage of refrigerant. As a result, since it is not necessary to provide a soundproofing material or the like in the apparatus for preventing noise, it is possible to reduce the material cost.

[0013] In addition, such pressure equalization control can be performed individually for the plurality of usage-side heat exchangers (41), and usage-side heat exchange during heating operation that does not require switching between cooling and heating operations. It is advantageous to ensure the air conditioning performance of the entire device without shutting down the unit (4 1).

[0014] A second invention includes a high-pressure gas pipe (11), a low-pressure gas pipe (12), a liquid pipe (13), and a plurality of usage-side heat exchangers (41), each of the usage-side heat exchanges. One end of the vessel (41) is connected to the liquid pipe (13) via an expansion mechanism (42), and the other end is connected to the high-pressure gas pipe (11) via a switching mechanism (30A, 30B). The air conditioner is connected to the low-pressure gas pipe (12) so as to be switchable, and each use-side heat exchanger (41) can be individually operated for cooling and heating.

[0015] The switching mechanism (30A, 30B) has a first control valve (31) whose opening degree is adjustable, and connects the use side heat exchanger (41) and the high pressure gas pipe (11). The high-pressure passage (38), the opening degree of which can be adjusted, and the refrigerant flow rate when fully opened is smaller than the first control valve (31)! /, The first sub-control valve (33 ), Is formed with a smaller pipe inner diameter than the high-pressure gas pipe (11), and is connected to the high-pressure passage (38) so as to bypass the first control valve (31) ( 18), a second control valve (32) whose opening degree is adjustable, a low pressure passage (39) connecting the use side heat exchanger (41) and the low pressure gas pipe (12), and an opening degree. Adjustable and fully opened refrigerant flow rate is smaller than the second control valve (32)! /, Has a second sub-control valve (34), and has a smaller pipe inner diameter than the low-pressure gas pipe (12). And a second bypass pipe (19) connected to the low pressure passage (39) so as to bypass the second control valve (32).

[0016] When the switching mechanism (30A, 30B) switches from the cooling operation to the heating operation, the switching mechanism (30A, 30B) closes the second control valve (32) and the second sub control valve (34), and then When the control valve (33) is slightly opened, and then the first control valve (31) is fully opened to open the high pressure passage (38), while switching from heating operation to cooling operation, the first control valve (31) and after closing the first sub-control valve (33), the second sub-control valve (34) is opened slightly, and then the second control valve (32) is fully opened, Open (39).

In the second invention, the switching mechanism (30A, 30B) causes the second control valve (32) and the second sub control valve to

After the (34) is closed, the first sub-control valve (33) is opened slightly, and the user-side heat exchanger (41) equalizes the pressure with the high-pressure gas pipe (11) before the first control valve (31 ) Is opened, and the cooling operation power is switched to heating operation. On the other hand, after the first control valve (31) and the first sub control valve (33) are closed by the switching mechanism (30A, 30B), the second sub control valve (34) is slightly opened, and the use side heat After the exchanger (41) equalizes pressure with the low-pressure gas pipe (12), the second control valve (32) is opened to switch from heating operation to cooling operation.

[0018] Therefore, for example, when switching from the cooling operation to the heating operation, the first sub control valve (33) is slightly opened, and a high-pressure refrigerant is supplied to the use-side heat exchanger (41) side that was in the low-pressure state. By introducing a small amount one by one, the user side heat exchanger (41) is gradually changed from a low pressure state to a high pressure state and pressure-equalized with the high pressure gas pipe (11). It is possible to prevent the refrigerant from flowing in abruptly and prevent the passage of refrigerant. Here, as the first and second sub control valves (33, 34), the refrigerant flow rate when fully opened is smaller than that of the first and second control valves (31, 32)! / Therefore, the flow rate of the refrigerant can be adjusted with a smaller opening adjustment range, and a further advantageous effect can be obtained in preventing the passage of refrigerant. [0019] A third invention includes a high-pressure gas pipe (11), a low-pressure gas pipe (12), a liquid pipe (13), and a plurality of usage-side heat exchangers (41), each of the usage-side heat exchanges. One end of the vessel (41) is connected to the liquid pipe (13) via an expansion mechanism (42), and the other end is connected to the high-pressure gas pipe (11) via a switching mechanism (30A, 30B). The air conditioner is connected to the low-pressure gas pipe (12) so as to be switchable, and each use-side heat exchanger (41) can be individually operated for cooling and heating.

[0020] The switching mechanism (30A, 30B) includes a first on-off valve (35) that allows or blocks refrigerant flow, and connects the use side heat exchanger (41) and the high-pressure gas pipe (11). A high-pressure passage (38) to be connected, a refrigerant flow rate that is freely adjustable in opening degree and smaller than that of the first on-off valve (35), and a first sub-control valve (33), and the high-pressure gas A first bypass pipe (18) formed with a pipe inner diameter smaller than that of the pipe (11) and connected to the high-pressure passage (38) so as to bypass the first on-off valve (35), and allows refrigerant flow Or a second on-off valve (36) for shutting off, a low-pressure passage (39) connecting the use side heat exchanger (41) and the low-pressure gas pipe (12), and an opening degree adjustable and fully opened The refrigerant flow rate is smaller than the second on-off valve (36)! /, Has a second sub-control valve (34), is formed with a pipe inner diameter smaller than the low-pressure gas pipe (12), 2 Bypass the on-off valve (36) And a second bypass pipe (19) connected to the low pressure passage (39).

[0021] The switching mechanism (30A, 30B), when switching from cooling operation to heating operation, closes the second on-off valve (36) and the second sub control valve (34), and then When the control valve (33) is slightly opened, and then the first on-off valve (35) is opened to open the high-pressure passage (38), while the heating operation is switched to the cooling operation, the first on-off valve (35) and the first sub control valve (33) are closed, then the second sub control valve (34) is opened slightly, and then the second open valve (36) is opened to open the low pressure passage ( 39) is opened.

[0022] In the third invention, the switching mechanism (30A, 30B) causes the second on-off valve (36) and the second sub-control valve.

After the (34) is closed, the first sub-control valve (33) is opened slightly, and the use side heat exchanger (41) equalizes pressure with the high-pressure gas pipe (11), then the first on-off valve (35 ) Is opened, and the cooling operation power is switched to heating operation. On the other hand, after the first on-off valve (35) and the first sub-control valve (33) are closed by the switching mechanism (30A, 30B), the second sub-control valve (34) is slightly opened, and the use side heat After the exchanger (41) equalizes pressure with the low-pressure gas pipe (12), the second on-off valve (36) is opened to switch from heating operation to cooling operation. Therefore, for example, when switching from the cooling operation to the heating operation, the first sub control valve (33) is slightly opened, and a high-pressure refrigerant is supplied to the use-side heat exchanger (41) side that has been in the low-pressure state. Introduce a small amount and gradually change the pressure on the use side heat exchanger (41) from the low pressure state to the high pressure state to equalize the pressure with the high pressure gas pipe (11). The high-pressure refrigerant is prevented from flowing into the side heat exchanger (41) abruptly, and the force S prevents the refrigerant from passing through.

[0024] Here, the first and second on-off valves (35, 36) are not used for pressure equalization control but allow or block the refrigerant flow, so that the control valve capable of adjusting the refrigerant flow rate. Thus, the refrigerant switching circuit of the air conditioner can be realized with a simple configuration that requires complicated control such as adjusting the opening.

[0025] In the fourth and sixth inventions, there is provided a capillary tube (37 on the downstream side of the first and second sub control valves (33, 34) in the first and second bypass pipes (18, 19). ) Is connected! /

[0026] In the fourth and sixth inventions, it is possible to secure the reduced pressure distance necessary for reducing the pressure of the refrigerant flowing through the first and second bypass pipes (18, 19) with the capillary tube (37). . In this way, if a long decompression distance is secured downstream of the first and second sub control valves (33, 34), the refrigerant passes through the first and second sub control valves (33, 34). This is advantageous for suppressing the generation of passing sound.

[0027] In the fifth and seventh inventions, downstream end portions of the first and second bypass pipes (18, 19) are formed in a trumpet shape in which a pipe inner diameter is gradually enlarged, and the high-pressure passage ( 38) and the low pressure passage (39), the downstream side of the first and second bypass pipes (18, 19) with respect to the downstream end thereof is connected to the first and second bypass pipes (18, 19). ) Extends in a straight line along the flow direction of the refrigerant flowing out.

[0028] In the fifth and seventh inventions, since the inner diameter of the downstream end of the first and second bypass pipes (18, 19) is gradually enlarged, the first and second bypass pipes The refrigerant smoothly flows from (18, 19) to the high pressure passage (38) and the low pressure passage (39). In addition, the downstream side of the high pressure passage (38) and the low pressure passage (39) with respect to the downstream end of the first and second bypass pipes (18, 19) is a straight line along the refrigerant flow direction. Therefore, the refrigerant flowing out from the first and second bypass pipes (18, 19) flows into the high pressure passage (38) and the low pressure passage (3 It is possible to prevent the occurrence of collision noise by colliding with the inner wall of the pipe in 9), and an advantageous effect can be obtained in suppressing the generation of noise due to the refrigerant.

The invention's effect

[0029] According to the first invention, for example, when switching from the cooling operation to the heating operation, the first control valve (31) is slightly opened, and the use side heat exchanger (41) side which has been in the low pressure state A small amount of high-pressure refrigerant is introduced into the system, and the user-side heat exchanger (41) is gradually changed from a low pressure state to a high-pressure state to equalize pressure with the high-pressure gas pipe (11). Therefore, the rapid flow of the high-pressure refrigerant is suppressed, and the passage of refrigerant can be prevented from being generated. As a result, there is no need to provide a soundproofing material or the like in the apparatus to prevent noise, and an additional effect is obtained that the material cost can be reduced.

[0030] In addition, such pressure equalization control can be performed individually for the plurality of usage-side heat exchangers (41), and usage-side heat exchange during heating operation that does not require switching between cooling and heating operations. It is advantageous to ensure the air conditioning performance of the entire device without shutting down the unit (4 1).

[0031] Further, according to the second invention, for example, when switching from the cooling operation to the heating operation, the first sub control valve (33) is slightly opened, and the use side heat exchanger that has been in the low pressure state is used. By introducing small amounts of high-pressure refrigerant into the (41) side and gradually changing the usage-side heat exchanger (41) from the low-pressure state to the high-pressure state and equalizing pressure with the high-pressure gas pipe (11), the usage-side heat exchanger ( 41), it is possible to prevent a high-pressure refrigerant from flowing suddenly and prevent the passage of refrigerant. Here, as the first and second sub-control valves (33, 34), the refrigerant flow rate when fully opened is smaller than the first and second control valves (31, 32)! /, Using the control valves! /, Therefore, the coolant flow rate can be adjusted with a smaller opening adjustment range, and a further advantageous effect can be obtained in preventing the passage of refrigerant.

[0032] According to the third aspect of the invention, for example, when switching from the cooling operation to the heating operation, the first sub control valve (33) is slightly opened, and the use side heat exchanger that has been in the low pressure state is used. The first on-off valve (35) is introduced by gradually introducing high-pressure refrigerant into the (41) side and gradually changing the pressure on the use-side heat exchanger (41) from the low pressure state to the high pressure state with the high pressure gas pipe (11). ) Is prevented from flowing into the user-side heat exchanger (41) abruptly, and refrigerant flow is suppressed. Generation of excessive sound can be prevented.

[0033] Here, the first and second on-off valves (35, 36) are not used for pressure equalization control, but allow or block the refrigerant flow. Therefore, the control valve can adjust the refrigerant flow rate. Thus, the refrigerant switching circuit of the air conditioner can be realized with a simple configuration that requires complicated control such as adjusting the opening.

[0034] Further, according to the fourth and sixth inventions, the depressurization distance required for depressurizing the refrigerant flowing through the first and second bypass pipes (18, 19) is set to the capacity tube (37). Can be secured. In this way, if the decompression distance is kept long downstream of the first and second sub control valves (33, 34), the refrigerant passes through the first and second sub control valves (33, 34). This is advantageous for suppressing the generation of passing sound during the operation.

[0035] According to the fifth and seventh inventions, the inner diameter of the downstream side end of the first and second bypass pipes (18, 19) is gradually enlarged. The refrigerant smoothly flows from the second bypass pipe (18, 19) to the high pressure passage (38) and the low pressure passage (39). In addition, the downstream side of the high pressure passage (38) and the low pressure passage (39) with respect to the downstream end of the first and second bypass pipes (18, 19) is a straight line along the refrigerant flow direction. Therefore, the refrigerant flowing out of the first and second bypass pipes (18, 19) collides with the inner wall of the high-pressure passage (38) and the low-pressure passage (39) and produces a collision sound. It is possible to prevent the occurrence of the noise, and an advantageous effect is obtained in suppressing the noise caused by the refrigerant.

Brief Description of Drawings

FIG. 1 is a refrigerant circuit diagram showing an overall configuration of an air-conditioning apparatus according to Embodiment 1 and an operation for cooling operation.

FIG. 2 is a refrigerant circuit diagram showing the heating operation.

FIG. 3 is a refrigerant circuit diagram showing the operation of air conditioning operation 1.

FIG. 4 is a refrigerant circuit diagram showing the operation of air conditioning operation 2.

FIG. 5 is a flowchart showing the control operation of pressure equalizing operation 1.

FIG. 6 is a flowchart showing the control operation of pressure equalizing operation 2.

FIG. 7 is a refrigerant circuit diagram showing the overall configuration of the air-conditioning apparatus according to Embodiment 2 and the operation of cooling operation. [FIG. 8] FIG. 8 is a diagram showing a piping configuration of a BS unit.

FIG. 9 is a flowchart showing the control operation of pressure equalizing operation 1.

FIG. 10 is a flowchart showing the control operation of pressure equalizing operation 2.

11] FIG. 11 is another refrigerant circuit diagram in which the overall configuration of the air conditioner is partially omitted.

FIG. 12 is another refrigerant circuit diagram showing the overall configuration of the air conditioner with a part thereof omitted.

10 Air conditioner

11 High-pressure gas piping

12 Low pressure gas piping

13 Liquid piping

18 D bypass piping

19 Second bypass piping

21 Compressor

23 Heat source side heat exchanger

30 Air conditioner

30A IBS unit (switching mechanism)

30B 2nd BS mute (switching mechanism)

31 First control valve

32 Second control valve

33 1st sub control valve

34 Second sub control valve

35 First on-off valve

36 Second open / close valve

37 Firefly tube

38 High pressure passage

39 Low pressure passage 41 Indoor heat exchanger (use side heat exchanger)

42 Indoor expansion valve (expansion mechanism)

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present invention, its application, or its use.

As shown in FIG. 1, the air conditioner (10) of the first embodiment is provided in a building or the like, and heats and cools each room. The air conditioner (10) includes an outdoor unit (20), two BS units (30A, 30B) as switching mechanisms, and two indoor units (40A, 40B). And these outdoor units (20) etc. are connected by the communication piping which is refrigerant piping, and comprise the refrigerant circuit (R). In the refrigerant circuit (R), the refrigerant circulates to perform a vapor compression refrigeration cycle.

[0040] The outdoor unit (20) constitutes a heat source unit. The outdoor unit (20) includes a main pipe (2c), a first branch pipe (2d), and a second branch pipe (2e), which are refrigerant pipes. The outdoor unit (20) includes a compressor (21), an outdoor heat exchanger (23), an outdoor expansion valve (24), and two electromagnetic valves (26, 27).

[0041] One end of the main pipe (2c) is connected to the liquid pipe (13) which is a communication pipe disposed outside the outdoor unit (20), and the other end is connected to the first branch pipe (2d) and the second pipe. Connected to one end of the branch pipe (2e). The other end of the first branch pipe (2d) is connected to a high-pressure gas pipe (11) which is a connecting pipe arranged outside the outdoor unit (20). The other end of the second branch pipe (2e) is connected to the low-pressure gas pipe (12), which is a connecting pipe arranged outside the outdoor unit (20).

[0042] The compressor (21) is a fluid machine for compressing the refrigerant, and is constituted by, for example, a high-pressure dome type scroll compressor. The discharge pipe (2a) of the compressor (21) is connected in the middle of the first branch pipe (2d), and the suction pipe (2b) is connected in the middle of the second branch pipe (2e). The suction pipe (2b) is provided with an accumulator (22).

[0043] The outdoor heat exchanger (23) is a cross-fin type fin-and-tube heat exchanger, and is provided in the middle of the main pipe (2c). The outdoor expansion valve (24) is an electronic expansion valve. And is provided closer to the liquid pipe (13) than the outdoor heat exchanger (23) in the main pipe (2c). An outdoor fan (25) is provided in the vicinity of the outdoor heat exchanger (23). The outdoor heat exchanger (23) is configured so that the refrigerant exchanges heat with the air taken in by the outdoor fan (25).

[0044] The two solenoid valves (26, 27) are a first solenoid valve (26) and a second solenoid valve (27). The first solenoid valve (26) is provided closer to the outdoor heat exchanger (23) than the connection point of the discharge pipe (2a) in the first branch pipe (2d). The second solenoid valve (27) is provided closer to the outdoor heat exchanger (23) than the connection point of the suction pipe (2b) in the second branch pipe (2e). These solenoid valves (26, 27) constitute a control valve that allows or blocks the refrigerant flow.

[0045] Each of the indoor units (40A, 40B) constitutes a use unit! Each indoor unit (40A, 40B) is connected to each BS unit (30A, 30B) by an intermediate pipe (17) which is a connecting pipe. That is, the first indoor unit (40A) and the first IBS unit (30A) are connected in pairs with the second indoor unit (40B) and the second BS unit (30B). On the other hand, the liquid pipe (13) is connected to the first indoor unit (40A). The second indoor unit (40B) is connected to the branch liquid pipe (16) branched from the middle of the liquid pipe (13)!

[0046] Each of the indoor units (40A, 40B) is an indoor heat exchanger connected to each other through a refrigerant pipe.

(41) and an indoor expansion valve (42). The indoor heat exchanger (41) is connected to the intermediate pipe (17). The indoor expansion valve (42) of the first indoor unit (40A) is connected to the liquid pipe (13), and the indoor expansion valve (42) of the second indoor unit (40B) is connected to the branch liquid pipe (16)! / The indoor heat exchanger (41) is a cross-fin type fin 'and' tube type heat exchanger. The indoor expansion valve (42) is an electronic expansion valve. An indoor fan (43) is provided in the vicinity of the indoor heat exchanger (41). The indoor heat exchanger (41) is configured so that the refrigerant exchanges heat with the air taken in by the indoor fan (43).

[0047] In addition to the intermediate pipe (17), a high-pressure gas pipe (11) and a low-pressure gas pipe (12) are connected to the first IBS unit (30A). In the IBS mute (30A), the intermediate pipe (17) and the high pressure gas pipe (11) form a high pressure passage (38), and the intermediate pipe (17) and the low pressure gas pipe (12) form a low pressure passage (39). The high-pressure passage (38) and the low-pressure passage (39) are joined and connected. In the IBS nut (30A), the high-pressure gas pipe (1 1) is provided with a first control valve (31) with adjustable opening, and a low pressure gas pipe (12) with a low pressure passage (39) is provided with a second control valve (32) with adjustable opening. /!

[0048] In addition to the intermediate pipe (17), the second BS unit (30B) includes a branched high-pressure gas pipe (14) branched from the middle of the high-pressure gas pipe (11), and a low-pressure gas pipe (12). A branch low-pressure gas pipe (15) branched from the middle is connected. In the second BS unit (30B), the first control valve (31) is provided in the branch high-pressure gas pipe (14) forming the high-pressure passage (38), and the branch low-pressure gas pipe (15) forming the low-pressure passage (39). ) Is provided with a second control valve (32). The liquid pipe (13) passes through the first IBS unit (30A), and the branch liquid pipe (16) passes through the second BS unit (30B).

[0049] The first and second control valves (31, 32) of each BS unit (30A, 30B) constitute an electric valve that adjusts the refrigerant flow rate by adjusting the opening. These first and second control valves (31, 32) are for switching the refrigerant flow by switching between opening and closing, and for switching the cooling / heating operation in each indoor unit (40A, 40B).

[0050] For example, when the indoor unit (40A, 40B) is in the cooling operation, the first control valve (31) is set to the closed state, and the second control valve (32) is set to the open state. The refrigerant evaporated in (41) flows to the low-pressure gas pipe (12). When the indoor units (40A, 40B) are in heating operation, the first control valve (31) is set to the open state and the second control valve (32) is set to the closed state, and the high pressure gas pipe (11) force is set. The gas refrigerant flows to the indoor heat exchanger (41) and condenses (dissipates heat).

[0051] The air conditioner (10) is provided with various pressure sensors (28, 29, 44). Specifically, the discharge pipe (2a) of the compressor (21) is provided with a discharge pressure sensor (28) for detecting the discharge pressure of the compressor (21). The suction pipe (2b) of the compressor (21) is provided with a suction pressure sensor (29) for detecting the suction pressure of the compressor (21) upstream of the accumulator (22). In addition, a heat exchange pressure sensor (44) for detecting the pressure of the indoor heat exchanger (41) is provided between the indoor heat exchanger (41) and the indoor expansion valve (42).

[0052] The air conditioner (10) includes a controller (50). This controller

(50) constitutes an opening degree control means for performing a pressure equalizing operation when switching between the air conditioning operation of at least one of the indoor units (40A, 40B). In this pressure equalization operation, when switching from cooling operation to heating operation, the indoor heat exchanger (41) equalizes pressure with the high-pressure gas pipe (11). Heating operating force When switching to cooling operation, the first and second control valves (31, 32) are controlled so that the indoor heat exchanger (41) equalizes pressure with the low-pressure gas pipe (12). Specific pressure equalization operation will be described later.

[0053] The controller (50) is provided with a pressure input section (51), a compressor control section (52), and a valve operation section (53).

[0054] The pressure input unit (51) receives detection pressures of the discharge pressure sensor (28), the suction pressure sensor (29), and the heat exchange pressure sensor (44) during pressure equalization operation. The valve operating section (53) adjusts the opening degree of the first and second control valves (31, 32) in the pressure equalizing operation.

[0055] The compressor control section (52) constitutes pressure control means for controlling the inlet pressure of the first and second control valves (31, 32) to a predetermined value or more in the pressure equalizing operation. Here, the inlet pressure of the first control valve (31) is the refrigerant pressure flowing into the first control valve (31) from the discharge pipe (2a) side of the compressor (21). The inlet pressure of the second control valve (32) is the refrigerant pressure flowing into the second control valve (32) from the indoor heat exchanger (41) side.

[0056] In the first embodiment, the detected pressure of the heat exchange pressure sensor (44) is used as the inlet pressure of the first and second control valves (31, 32). If the heat exchange pressure sensor (44) cannot be detected due to a failure or the like, the detected pressure of the discharge pressure sensor (28) is substituted for the inlet pressure of the first control valve (31), and the suction pressure sensor (29) Is used as the inlet pressure of the second control valve (32).

[0057] Driving action

Next, the operation of the air conditioner (10) will be described with reference to the drawings. In this air conditioner (10), there are an operation in which both of the two indoor units (40A, 40B) perform cooling or heating, and an operation in which one performs cooling and the other performs heating.

[0058] <Cooling operation>

A case where both the first indoor unit (40A) and the second indoor unit (40B) perform the cooling operation will be described with reference to FIG. In this cooling operation, in the outdoor unit (20), the first solenoid valve (26) is set to the open state, the second solenoid valve (27) is set to the closed state, and the outdoor expansion valve (24) is set to the fully open state. The In each BS unit (30A, 30B), the first control valve (31) is set to the closed state, and the second control valve (32) is set to the open state. Each indoor unit (40A , 40B), the indoor expansion valve (42) is set to an appropriate opening degree.

[0059] When the compressor (21) is driven in such a state, the high-pressure gas refrigerant discharged from the compressor (21) passes through the first branch pipe (2d) to the outdoor heat exchanger (23). Flowing. In the outdoor heat exchanger (23), the refrigerant condenses by exchanging heat with the air taken in by the outdoor fan (25). The condensed refrigerant flows outside the outdoor unit (20) through the main pipe (2c) and flows into the liquid pipe (13). Part of the refrigerant in the liquid pipe (13) flows into the branch liquid pipe (16) and flows into the second indoor unit (40B), and the rest flows into the first indoor unit (40A).

[0060] In the first indoor unit (40A) and the second indoor unit (40B), the refrigerant is an indoor expansion valve.

After being depressurized in (42), it flows to the indoor heat exchanger (41). In the indoor heat exchanger (41), the refrigerant evaporates by exchanging heat with the air taken in by the indoor fan (43). This cools the air and cools the room. The gas refrigerant evaporated in the indoor heat exchanger (41) flows out of the indoor units (40A, 40B), and flows into the BS units (3OA, 30B) through the intermediate pipe (17).

[0061] In the first IBS unit (30A), the gas refrigerant flows from the intermediate pipe (17) into the low-pressure gas pipe (12). In the second BS unit (30B), the gas refrigerant flows from the intermediate pipe (17) into the branch low-pressure gas pipe (15) and then flows into the low-pressure gas pipe (12). The gas refrigerant in the low-pressure gas pipe (12) flows into the outdoor unit (20), returns to the compressor (21) through the suction pipe (2b), and this circulation is repeated.

[0062] <Heating operation>

A case where both the first indoor unit (40A) and the second indoor unit (40B) perform the heating operation will be described with reference to FIG. In this heating operation, in the outdoor unit (20), the first solenoid valve (26) is closed, the second solenoid valve (27) is opened, and the outdoor expansion valve (24) is set to an appropriate opening degree. Is set. In each BS unit (30A, 30B), the first control valve (31) is set in the open state, and the second control valve (32) is set in the closed state. In each indoor unit (40 A, 40B), the indoor expansion valve (42) is set to a fully open state.

[0063] When the compressor (21) is driven in such a state, the high-pressure gas refrigerant discharged from the compressor (21) flows out of the outdoor unit (20) and flows into the high-pressure gas pipe (11). . Part of the refrigerant in the high-pressure gas pipe (11) is branched from the high-pressure gas pipe (14) to the second BS unit (30B). It flows in and the rest flows into the IBS unit (30A). The refrigerant flowing into each BS unit (30A, 30B) flows into each indoor unit (40A, 40B) through the intermediate pipe (17).

[0064] In each of the indoor units (40A, 40B), the refrigerant condenses by exchanging heat with air. This heats the air and heats the room. The refrigerant condensed in the first indoor unit (40A) flows to the liquid pipe (13). The refrigerant condensed in the second indoor unit (40B) flows into the liquid pipe (13) through the branch liquid pipe (16). The refrigerant in the liquid pipe (13) flows into the outdoor unit (20) and flows through the main pipe (2c). The refrigerant in the main pipe (2c) is decompressed by the outdoor expansion valve (24) and then flows into the outdoor heat exchanger (23). In the outdoor heat exchanger (23), the refrigerant exchanges heat with air and evaporates. The evaporated gas refrigerant returns to the compressor (21) again through the second branch pipe (2e) and the suction pipe (2b), and this circulation is repeated.

[0065] <Air-conditioning operation>

Next, a case where the cooling operation is performed in one indoor unit (40A, 40B) and the heating operation is performed in the other indoor unit (4OA, 40B) will be described.

First, an operation in which the cooling operation is performed in the first indoor unit (40A) and the heating operation is performed in the second indoor unit (40B) (hereinafter referred to as air conditioning operation 1) will be described. Here, differences from the cooling operation will be described.

In the cooling / heating operation 1, as shown in FIG. 3, in the cooling operation state described above, the first control valve (31) of the second BS unit (30B) is opened, and the second control valve (32 ) Is set to the closed state. Further, the indoor expansion valve (42) of the second indoor unit (40B) is set to a fully open state. Then, a part of the high-pressure gas refrigerant discharged from the compressor (21) flows to the first branch pipe (2d) and the rest flows to the high-pressure gas pipe (11).

[0068] The refrigerant that has flowed into the high-pressure gas pipe (11) flows from the branch high-pressure gas pipe (14) to the second BS unit (

30B) and the intermediate pipe (17) to the indoor heat exchanger (41) of the second indoor unit (40B). In the indoor heat exchanger (41) of the second indoor unit (40B), the refrigerant exchanges heat with air and condenses. Thereby, air is heated and indoor heating is performed.

[0069] The refrigerant condensed in the second indoor unit (40B) flows into the liquid pipe (13) through the branch liquid pipe (16), and merges with the refrigerant from the outdoor unit (20). The combined refrigerant flows through the liquid pipe (13) as it is, and evaporates in the first indoor unit (40A). This will cool the room It is.

Next, an operation in which the heating operation is performed in the first indoor unit (40A) and the cooling operation is performed in the second indoor unit (40B) (hereinafter referred to as air conditioning operation 2) will be described. Here, differences from the heating operation will be described.

In the case of this cooling / heating operation 2, as shown in FIG. 4, in the heating operation state described above, the first control valve (31) of the second BS unit (30B) is closed, and the second control valve (32 ) Is set to the open state. Further, the indoor expansion valve (42) of the second indoor unit (40B) is set to an appropriate opening degree. Then, the entire amount of refrigerant flowing into the compressor (21) force high pressure gas pipe (11) flows into the first IBS unit (30A). The refrigerant flowing through the first IBS unit (30A) flows to the first indoor unit (40A) and condenses. As a result, heating operation is neglected in the first indoor unit (40A).

[0072] The refrigerant condensed in the first indoor unit (40A) flows to the liquid pipe (13). Part of the refrigerant in the liquid pipe (13) flows into the second indoor unit (40B) through the branch liquid pipe (16), and the rest flows into the outdoor unit (20). In the second indoor unit (40B), the refrigerant is depressurized by the indoor expansion valve (42) and then evaporated by the indoor heat exchanger (41). As a result, cooling is performed in the second indoor unit (40B).

[0073] The gas refrigerant evaporated in the second indoor unit (40B) flows into the low-pressure gas pipe (12) through the intermediate pipe (17), the second BS unit (30B) and the branch low-pressure gas pipe (15) in this order. To do. The refrigerant in the low-pressure gas pipe (12) flows into the second branch pipe (2e) of the outdoor unit (20) and merges with the refrigerant from the outdoor heat exchanger (23). The merged refrigerant returns to the compressor (21) again through the suction pipe (2b).

[0074] <Pressure equalizing operation 1>

Next, pressure equalization operation 1 performed when switching from the above-described cooling operation state to air conditioning operation 1 will be described with reference to FIGS. 1 and 5. The first control valve (31), the second control valve (32), the indoor expansion valve (42), the heat exchange pressure sensor (44), etc. described below are the second BS unit (30B) and the second indoor valve. Assume that it is in the unit (40B).

[0075] In this pressure equalizing operation 1, the controller (50) performs the control shown in FIG. First, in step S 11, the valve operating section (53) closes the second control valve (32). As a result, the second BS unit (3 OB) and the refrigerant flow to the second indoor unit (40B) are blocked.

[0076] Next, in step S12, the valve operating section (53) slightly opens the first control valve (31). In other words, the refrigerant discharged from the compressor (21) passes through the high-pressure passage (38) of the second BS unit (30B), that is, the low-pressure indoor heat exchange through the branch high-pressure gas pipe (14) and the intermediate pipe (17). Pour into the vessel (41) little by little. As a result, the indoor heat exchanger (41) in the low pressure state is gradually equalized to the same high pressure state as the branch high pressure gas pipe (14).

[0077] Next, in step S13, the valve operating section (53) fully opens the first control valve (31). As a result, the refrigerant discharged from the compressor (21) flows into the indoor heat exchanger (41) through the branch high-pressure gas pipe (14) and the intermediate pipe (17), and the switching from the cooling operation to the heating operation is completed. The Here, since the indoor heat exchanger (41) is pre-equalized with the branch high-pressure gas pipe (14), the high-pressure refrigerant is prevented from flowing into the indoor heat exchanger (41) rapidly, and the refrigerant The generation of passing sound can be prevented.

[0078] As described above, in the pressure equalizing operation 1 of the first embodiment, when switching from the cooling operation to the heating operation, the first control valve (31) is slightly opened, and the indoor heat that has been in the low pressure state is set. High pressure refrigerant was introduced little by little on the exchanger (41) side, and the indoor heat exchanger (41) was gradually changed from a low pressure state to a high pressure state so as to equalize pressure with the branch high pressure gas pipe (14). Therefore, the high-pressure refrigerant is prevented from flowing into the indoor heat exchanger (41) suddenly, and generation of refrigerant passage noise can be prevented. As a result, there is no need to provide a soundproofing material or the like for preventing noise in the apparatus, so that an additional effect that the material cost can be reduced can be obtained.

[0079] <Pressure equalizing operation 2>

Next, the pressure equalizing operation 2 performed when switching from the heating operation state to the air conditioning operation 2 will be described with reference to FIGS. The first control valve (31), the second control valve (32), the indoor expansion valve (42), the heat exchange pressure sensor (44), etc. described below are the second BS unit (30B) and the second indoor valve. It is in the unit (40B).

[0080] In this pressure equalizing operation 2, the controller (50) performs the control shown in FIG. First, in step S21, the valve operating section (53) closes the first control valve (31). Thereby, the distribution of the refrigerant to the second BS unit (30B) and the second indoor unit (40B) is blocked.

[0081] Next, in step S22, the valve operating section (53) slightly opens the second control valve (32). The That is, the refrigerant discharged from the compressor (21) flows into the branch low-pressure gas pipe (15) little by little through the indoor heat exchanger (41) and the intermediate pipe (17). As a result, the indoor heat exchanger (41) in the high pressure state is gradually equalized to the same low pressure state as the branch low pressure gas pipe (15).

[0082] Next, in step S23, the valve operating section (53) fully opens the second control valve (32). As a result, the refrigerant discharged from the compressor (21) flows into the branch low-pressure gas pipe (15) through the indoor heat exchanger (41) and the intermediate pipe (17), and the switching from the heating operation to the cooling operation is completed. Here, since the indoor heat exchanger (41) is pre-equalized with the branch low-pressure gas pipe (15), the high-pressure refrigerant suddenly flows into the indoor heat exchanger (41) force branch low-pressure gas pipe (15). It is possible to prevent the refrigerant from passing through and to prevent the passage of refrigerant.

[0083] As described above, in the pressure equalizing operation 2 of the first embodiment, when switching from the heating operation to the cooling operation, the second control valve (32) is slightly opened, and the indoor heat that has been in the high pressure state is set. A small amount of high-pressure refrigerant is introduced from the exchanger (41) to the branch low-pressure gas pipe (15) side, and the indoor heat exchanger (41) is gradually changed from the high pressure state to the low-pressure state. The pressure was equalized. Therefore, the high-pressure refrigerant is prevented from flowing suddenly from the indoor heat exchanger (41) into the branch low-pressure gas pipe (15), and the passage of refrigerant can be prevented from being generated.

FIG. 7 is a refrigerant circuit diagram showing the overall configuration of the air-conditioning apparatus (30) according to Embodiment 2 of the present invention and the operation of the cooling operation. The difference from Embodiment 1 is that the first and second bypass pipes (18, 19) bypassing the first and second control valves (31, 32) and the first and second bypass pipes (18, 19) Since the first and second sub control valves (33, 34) provided in the first embodiment are provided, the same parts as those in the first embodiment are denoted by the same reference numerals, and only different points will be described.

As shown in FIG. 7, in addition to the intermediate pipe (17), the high pressure gas pipe (11) and the low pressure gas pipe (12) are connected to the first IBS unit (30A). In the IBS unit (30A), the intermediate pipe (17) and the high-pressure gas pipe (11) form a high-pressure passage (38), and the intermediate pipe (17) and the low-pressure gas pipe (12) form a low-pressure passage (39). The high-pressure passage (38) and the low-pressure passage (39) are joined and connected. In the IBS mute (30A), the high pressure gas pipe (11) is provided with the first control valve (31), and the low pressure gas pipe (12) is provided with the second control valve (32). , [0086] Further, a first bypass pipe (18) is connected to the high pressure passage (38) so as to bypass the first control valve (31), and a second control valve (32) is connected to the low pressure passage (39). The second bypass pipe (19) is connected to bypass. The first and second bypass pipes (18, 19) are formed with smaller pipe inner diameters than the high-pressure gas pipe (11) and the low-pressure gas pipe (12), respectively. The first and second bypass pipes (18, 19) are adjustable in opening and the refrigerant flow rate when fully opened is smaller than that of the first and second control valves (31, 32)! /, 1 and 2 sub control valves (33, 34) are installed.

[0087] In addition to the intermediate pipe (17), the second BS unit (30B) includes a branch high-pressure gas pipe (14) branched from the middle of the high-pressure gas pipe (11), and a low-pressure gas pipe (12). A branch low-pressure gas pipe (15) branched from the middle is connected. In the second BS unit (30B), the branch high-pressure gas pipe (14) is provided with a first control valve (31), and the branch low-pressure gas pipe (15) is provided with a second control valve (32). ! /

[0088] Further, a first bypass pipe (18) is connected to the branch high-pressure gas pipe (14) so as to bypass the first control valve (31), and a second control is connected to the branch low-pressure gas pipe (15). A second bypass pipe (19) is connected to bypass the valve (32). Each of the first and second bypass pipes (18, 19) has a smaller pipe inner diameter than the branch high-pressure gas pipe (14) and the branch low-pressure gas pipe (15). In the first and second bypass pipes (18, 19), the refrigerant flow rate when fully opened is smaller than that of the first and second control valves (31, 32)! /, The first and second sub control valves ( 33, 34).

Here, as shown in FIG. 8, the downstream ends of the first and second bypass pipes (18, 19) are formed in a trumpet shape with the pipe inner diameter gradually enlarged. Then, in the high pressure passage (38), the downstream side of the connection position with the downstream end of the first bypass pipe (18), that is, the connection pipe between the high pressure gas pipe (11) and the indoor heat exchanger (41). The intermediate pipe (17) connected to the downstream end of the first bypass pipe (18) extends linearly along the flow direction of the refrigerant that also flows out the force of the first bypass pipe (18). Has been placed.

[0090] In addition, the low pressure passage (39) is connected to the downstream end of the second bypass pipe (19), that is, to the downstream end of the second bypass pipe (19). Low pressure gas The pipe (12) is arranged so as to extend linearly along the flow direction of the refrigerant from which the second bypass pipe (19) force also flows.

[0091] As described above, since the pipe inner diameters at the downstream ends of the first and second bypass pipes (18, 19) are gradually enlarged, the first and second bypass pipes (18, 19) The refrigerant flows smoothly into the intermediate pipe (17) and low-pressure gas pipe (12). The intermediate pipe (17) and the low-pressure gas pipe (12) connected to the downstream ends of the first and second bypass pipes (18, 19) extend linearly along the refrigerant flow direction. Therefore, the refrigerant flowing out from the first and second bypass pipes (18, 19) is the inner wall of the intermediate pipe (17) and the low pressure gas pipe (12) forming the high pressure passage (38) and the low pressure passage (39). It is possible to prevent a collision noise from being generated by colliding with the refrigerant, and an advantageous effect can be obtained in suppressing the generation of noise caused by the refrigerant.

[0092] In the pressure equalizing operation, the controller (50) is operated by the valve operating unit (53), and the first and second control valves (31, 32), and the first and second sub-control valves. It is configured to adjust the opening of (33, 34).

[0093] Driving action

Next, the operation of the air conditioner (30) will be described with reference to the drawings. In this air conditioner (30), there are an operation in which both of the two indoor units (40A, 40B) perform cooling or heating, and an operation in which one performs cooling and the other performs heating. Since the cooling operation, the heating operation, and the cooling / heating operation are substantially the same as the operation operations described in the first embodiment, only the cooling operation is described in the second embodiment, and the other operation operations are omitted. .

[0094] <Cooling operation>

A case where both the first indoor unit (40A) and the second indoor unit (40B) perform the cooling operation will be described with reference to FIG. In this cooling operation, in the outdoor unit (20), the first solenoid valve (26) is set to the open state, the second solenoid valve (27) is set to the closed state, and the outdoor expansion valve (24) is set to the fully open state. The In each BS unit (30A, 30B), the first control valve (31), the first and second sub control valves (33, 34) are closed, and the second control valve (32) is opened. Is set. In each indoor unit (40A, 40B), the indoor expansion valve (42) is set to an appropriate opening degree. In this state, when the compressor (21) is driven, the high-pressure gas refrigerant discharged from the compressor (21) passes through the first branch pipe (2d) to the outdoor heat exchanger (23). Flowing. In the outdoor heat exchanger (23), the refrigerant condenses by exchanging heat with the air taken in by the outdoor fan (25). The condensed refrigerant flows outside the outdoor unit (20) through the main pipe (2c) and flows into the liquid pipe (13). Part of the refrigerant in the liquid pipe (13) flows into the branch liquid pipe (16) and flows into the second indoor unit (40B), and the rest flows into the first indoor unit (40A).

[0096] In the first indoor unit (40A) and the second indoor unit (40B), the refrigerant is an indoor expansion valve.

In the first IBS unit (30A), the gas refrigerant flows from the intermediate pipe (17) into the low-pressure gas pipe (12). In the second BS unit (30B), the gas refrigerant flows from the intermediate pipe (17) into the branch low-pressure gas pipe (15) and then flows into the low-pressure gas pipe (12). The gas refrigerant in the low-pressure gas pipe (12) flows into the outdoor unit (20), returns to the compressor (21) through the suction pipe (2b), and this circulation is repeated.

[0098] <Pressure equalizing operation 1>

Next, pressure equalization operation 1 performed when switching from the above-described cooling operation state to air conditioning operation 1 will be described with reference to FIGS. The first and second control valves (31, 32), the first and second sub control valves (33, 34), the indoor expansion valve (42), the heat exchange pressure sensor (44), etc. It is assumed that it is in the second BS unit (30B) and the second indoor unit (40B).

[0099] In the pressure equalizing operation 1, the controller (50) performs the control shown in FIG. First, in step S31, the valve operating section (53) closes the second control valve (32) and the second sub control valve (34). As a result, the refrigerant flow to the second BS unit (30B) and the second indoor unit (40B) is blocked.

[0100] Next, in step S32, the valve operating section (53) slightly opens the first sub control valve (33). That is, the refrigerant discharged from the compressor (21) flows little by little to the low-pressure indoor heat exchanger (41) through the branch high-pressure gas pipe (14), the first bypass pipe (18), and the intermediate pipe (17). Include. As a result, the indoor heat exchanger (41) in the low-pressure state is gradually equalized to the same high-pressure state as the branch high-pressure gas pipe (14).

[0101] Next, in step S33, the valve operating portion (53) fully opens the first control valve (31). The first sub control valve (33) may remain open or may be controlled to close when the first control valve (31) is opened.

[0102] As a result, the refrigerant discharged from the compressor (21) is branched into the high-pressure gas pipe (14) and the first bypass pipe.

(18) and the intermediate pipe (17) flow into the indoor heat exchanger (41), completing the switching from the cooling operation to the heating operation. Here, since the indoor heat exchanger (41) is pre-equalized with the branch high-pressure gas pipe (14), the high-pressure refrigerant is prevented from flowing into the indoor heat exchanger (41). The generation of the passage sound of the refrigerant can be prevented.

[0103] As described above, in the pressure equalizing operation 1 of the second embodiment, when switching from the cooling operation to the heating operation, the first sub control valve (33) is slightly opened, and the room is in the low pressure state. A small amount of high-pressure refrigerant was introduced to the heat exchanger (41) side, and the indoor heat exchanger (41) was gradually changed from a low pressure state to a high pressure state so as to equalize pressure with the branch high-pressure gas pipe (14). Therefore, the high-pressure refrigerant can be prevented from flowing into the indoor heat exchanger (41) rapidly, and the generation of passage noise of the refrigerant can be prevented. Here, as the first sub control valve (33), the refrigerant flow rate when fully opened is smaller than that of the first control valve (31)! The flow rate of the refrigerant can be adjusted within the adjustment range, and a further advantageous effect can be obtained in preventing the generation of the passage sound of the refrigerant.

[0104] <Pressure equalizing operation 2>

Next, pressure equalization operation 2 performed when switching from the above-described heating operation state to air-conditioning operation 2 (see Embodiment 1) will be described with reference to FIG. The first and second control valves (31, 32), the first and second sub control valves (33, 34), the indoor expansion valve (42), the heat exchange pressure sensor (44), etc. This is in the second BS unit (30B) and the second indoor unit (40B).

[0105] In the pressure equalizing operation 2, the controller (50) performs the control shown in FIG. First, step S At 41, the valve operating section (53) closes the first control valve (31) and the first sub control valve (33). As a result, the refrigerant flow to the second BS unit (30B) and the second indoor unit (40B) is blocked.

[0106] Next, in step S42, the valve operating section (53) slightly opens the second sub control valve (34).

That is, the refrigerant discharged from the compressor (21) flows into the branch low-pressure gas pipe (15) little by little through the indoor heat exchanger (41), the intermediate pipe (17), and the second bypass pipe (19). As a result, the high-pressure indoor heat exchanger (41) and the like are gradually pressure-equalized to the same low-pressure state as the branch low-pressure gas pipe (15).

[0107] Next, in step S43, the valve operating section (53) fully opens the second control valve (32). The second sub control valve (34) may remain open or may be controlled to close when the second control valve (32) is opened.

[0108] As a result, the refrigerant discharged from the compressor (21) flows into the branch low-pressure gas pipe (15) through the indoor heat exchanger (41), the intermediate pipe (17), and the second bypass pipe (19). Switching from to cooling operation is completed. Here, since the indoor heat exchanger (41) is pre-equalized with the branch low-pressure gas pipe (15), a high-pressure refrigerant flows from the indoor heat exchanger (41) to the branch low-pressure gas pipe (15). Abrupt inflow is suppressed, and it is possible to prevent the generation of refrigerant passage noise.

As described above, in the pressure equalizing operation 2 of the present embodiment 2, when switching from the heating operation to the cooling operation, the second sub-control valve (34) is slightly opened, and the room that has been in the high pressure state is used. High pressure refrigerant is introduced into the heat exchanger (41) and the branch low pressure gas pipe (15) little by little, and the indoor heat exchanger (41) is gradually changed from the high pressure state to the low pressure state to branch low pressure gas pipe (15 ) And pressure equalization. Therefore, the high-pressure refrigerant is prevented from flowing suddenly from the indoor heat exchanger (41) into the branch low-pressure gas pipe (15), and the passage of refrigerant can be prevented from being generated. Here, as the second sub-control valve (34), the refrigerant flow rate when fully opened is smaller than the second control valve (32)! /, And the control valve is used. This can be adjusted, and a further advantageous effect can be obtained in preventing the generation of the passage sound of the refrigerant.

According to the above embodiment, the following configuration is possible. [0111] For example, in the air conditioner (30) of the second embodiment, as shown in Fig. 11, the first and second sub control valves (33, 33) in the first and second bypass pipes (18, 19) It is also possible to have a configuration in which a capillary tube (37) is connected downstream of 34)! /.

[0112] By doing this, the capillary tube (37) is connected to the downstream side of the first and second auxiliary control valves (33, 34) in the first and second bypass pipes (18, 19). For example, it is possible to secure the decompression distance necessary for decompressing the refrigerant flowing through the first and second bypass pipes (18, 19) with the capillary tube (37). That is, if a long decompression distance is secured downstream of the first and second sub control valves (33, 34), the refrigerant will pass through the first and second sub control valves (33, 34). This is advantageous in suppressing the generation of the passing sound.

[0113] In the second embodiment, the indoor heat exchanger (41) includes the first and second control valves (adjustable refrigerant flow rate) in the high-pressure gas pipe (11) and the low-pressure gas pipe (12). 31, 32) Forces connected in a switchable manner As shown in FIG. 12, which is not limited to this form, instead of the first and second control valves (31, 32), the refrigerant flow is changed. The first and second open / close valves (35, 36) that allow or shut off may be used.

[0114] In this case, after the second on-off valve (36) and the second sub-control valve (34) are closed by the controller (50), the first sub-control valve (33) is slightly opened, and the indoor heat After the exchanger (41) equalizes pressure with the high-pressure gas pipe (11), the first on-off valve (35) is opened to switch from the cooling operation to the heating operation. On the other hand, after the first on-off valve (35) and the first sub-control valve (33) are closed by the controller (50), the second sub-control valve (34) is opened slightly, and the indoor heat exchanger ( After the pressure is equalized with the low pressure gas pipe (12), the second on-off valve (36) is opened and the heating operation is switched to the cooling operation X_.

In this way, for example, when switching from the cooling operation to the heating operation, the first sub control valve (33) is slightly opened, and the high pressure is applied to the indoor heat exchanger (41) side in the low pressure state. A small amount of refrigerant is introduced, and the indoor heat exchanger (41) is gradually changed from a low pressure state to a high pressure state to equalize pressure with the high pressure gas pipe (11). The high-pressure refrigerant is prevented from flowing into the heat exchanger (41) abruptly, and the force S prevents the passage of refrigerant.

[0116] Here, the first and second on-off valves (35, 36) are not used for pressure equalization control but are used for refrigerant flow. Therefore, the refrigerant switching circuit of the air conditioner is realized with a simple configuration that does not require complicated control such as adjusting the opening, such as a control valve that can adjust the refrigerant flow rate. be able to.

[0117] In the first and second embodiments, the force S described for the configuration in which two indoor units (40A, 40B) and two BS units (30A, 30B) are provided is provided in a configuration having three or more units each. Even if it exists, generation | occurrence | production of the passage sound of a refrigerant | coolant can be suppressed similarly.

Industrial applicability

[0118] As described above, the present invention provides a highly practical effect of ensuring the air conditioning performance of the entire air conditioner while preventing the passage of refrigerant that occurs when switching between cooling and heating operations. Therefore, it is extremely useful and has high industrial applicability.

Claims

The scope of the claims

A high-pressure gas pipe (11), a low-pressure gas pipe (12), a liquid pipe (13), and a plurality of usage-side heat exchangers (41).

One end of each use side heat exchanger (41) is connected to the liquid pipe (13) via an expansion mechanism (42), while the other end is connected to the high pressure via a switching mechanism (30A, 30B). The gas pipe (11) and the low-pressure gas pipe (12) are switchably connected,

Each of the use side heat exchangers (41) is an air conditioner capable of individually cooling and heating, and the switching mechanism (30A, 30B)

A high-pressure passage (38) having a first control valve (31) with adjustable opening, and connecting the use-side heat exchanger (41) and the high-pressure gas pipe (11);

While having a second control valve (32) whose opening degree is adjustable, and having a low pressure passage (39) connecting the use side heat exchanger (41) and the low pressure gas pipe (12),

When switching from the cooling operation to the heating operation, the first control valve (31) is slightly opened after the second control valve (32) is closed, and then the first control valve (31) is fully opened. When switching from heating operation to cooling operation while opening the high-pressure passage (38), the second control valve (32) is slightly opened after the first control valve (31) is closed, and then the An air conditioner configured to open the low-pressure passage (39) with the second control valve (32) fully open!

A first control valve (31) whose opening degree is adjustable, and the use side heat exchanger (41) and the high pressure gas High-pressure passage (38) connecting the pipe (11),

Adjustable opening and flow rate of refrigerant when fully open is smaller than the first control valve (31)! / ヽ The first sub control valve (33) has a smaller diameter than the high-pressure gas pipe (11) A first bypass pipe formed with an inner diameter and connected to the high-pressure passage (38) so as to bypass the first control valve (31)

(18)

A low-pressure passage (39) having a second control valve (32) with adjustable opening, and connecting the use-side heat exchanger (41) and the low-pressure gas pipe (12);

Adjustable opening and flow rate of refrigerant when fully open is smaller than the second control valve (32)! /, Has a second sub-control valve (34) and has a smaller diameter than the low-pressure gas pipe (12) A second bypass pipe formed with an inner diameter and connected to the low pressure passage (39) so as to bypass the second control valve (32)

(19)

When switching from the cooling operation to the heating operation, the first sub control valve (33) is slightly opened after the second control valve (32) and the second sub control valve (34) are closed, and then the first sub control valve (33) is opened. 1 When the control valve (31) is fully opened and the high pressure passage (38) is opened while the heating operation is switched to the cooling operation, the first control valve (31) and the first sub control valve (33) are The second sub control valve (34) is slightly opened after being closed, and then the second control valve (32) is fully opened to open the low pressure passage (39). Air conditioner.

[3] High-pressure gas pipe (11), low-pressure gas pipe (12), liquid pipe (13), and multiple use side heat exchangers (4

1)

A high pressure passage (38) having a first on-off valve (35) for allowing or blocking the refrigerant flow, and connecting the use side heat exchanger (41) and the high pressure gas pipe (11);

Adjustable opening and refrigerant flow when fully open is smaller than the first on-off valve (35)! It has a sub-control valve (33), is formed with a smaller pipe inner diameter than the high-pressure gas pipe (11), and is connected to the high-pressure passage (38) so as to bypass the first on-off valve (35) 1st bypass piping

(18)

A low-pressure passage (39) having a second on-off valve (36) for allowing or blocking the refrigerant flow, and connecting the use-side heat exchanger (41) and the low-pressure gas pipe (12);

Adjustable opening and flow rate of refrigerant when fully open is smaller than the second on-off valve (36)! / Has a second sub-control valve (34) and has a smaller diameter than the low-pressure gas pipe (12) A second bypass pipe formed with an inner diameter and connected to the low pressure passage (39) so as to bypass the second on-off valve (36)

(19)

When switching from the cooling operation to the heating operation, the first sub-control valve (33) is slightly opened after closing the second on-off valve (36) and the second sub-control valve (34), and then the first 1 When opening and closing the valve (35) and opening the high-pressure passage (38) while switching from heating operation to cooling operation, the first on-off valve (35) and the first sub-control valve (33) The second sub control valve (34) is slightly opened after closing, and then the second on-off valve (36) is opened to open the low pressure passage (39). Air conditioner.

In claim 2,

A capillary tube (37) is connected to the first and second bypass pipes (18, 19) downstream of the first and second sub control valves (33, 34). Air conditioning device.

In claim 2,

The downstream ends of the first and second bypass pipes (18, 19) are formed in a trumpet shape in which the pipe inner diameter is gradually enlarged,

In the high-pressure passage (38) and the low-pressure passage (39), the first and second bypass pipes are located downstream of the connection positions with the downstream ends of the first and second bypass pipes (18, 19). An air conditioner that extends in a straight line along the flow direction of the refrigerant flowing out of (18, 19).

In claim 3,

The first and second sub control valves (33, 33) in the first and second bypass pipes (18, 19) 34) An air conditioner characterized in that a downstream tube (37) is connected to the downstream side.

In claim 3,