WO2019044661A1

WO2019044661A1 - Multi-type air conditioning system and indoor unit

Info

Publication number: WO2019044661A1
Application number: PCT/JP2018/031203
Authority: WO
Inventors: シノトクタナウィット; トンチュームパユンデッド; 将嗣山元
Original assignee: 東芝キヤリア株式会社; トウシバ・キヤリア（タイランド）・カンパニー・リミテッド
Priority date: 2017-08-29
Filing date: 2018-08-23
Publication date: 2019-03-07
Also published as: JPWO2019044661A1; EP3677856A4; JP6828176B2; EP3677856A1; CN111094876A

Abstract

The multi-type air conditioning system according to the present invention includes: an outdoor unit having an outside air heat exchanger; a plurality of indoor units each having an expansion valve into which a refrigerant flows after passing through the outdoor heat exchanger, and an indoor heat exchanger which exchanges heat between the refrigerant decompressed by the expansion valve and air; and a refrigerant pipe which connects the plurality of indoor units in parallel to the outdoor unit and through which the refrigerant flows. The refrigerant pipe located inside each of the indoor units has a plurality of capillaries at the location upstream of the expansion valve and along the flow direction of the refrigerant, and the capillaries are connected in parallel to the refrigerant pipe.

Description

Multi-type air conditioning system and indoor unit

Embodiments of the present invention relate to a multi-type air conditioning system and an indoor unit.

For example, in a multi-type air conditioning system in which a plurality of indoor units are connected to one outdoor unit, the amount of refrigerant supplied to each indoor unit changes every moment depending on the room temperature or the usage condition of the indoor units. For this reason, the refrigerant supplied from the outdoor unit to the indoor unit may change from the liquid phase flow to the gas-liquid two-phase flow state depending on the flow conditions of the refrigerant to the plurality of indoor units.

It is known that when the gas-liquid two-phase refrigerant flows into the expansion valve of the indoor unit, an unpleasant refrigerant flow noise is generated. That is, the refrigerant flow noise depends on the flow mode of the gas-liquid two-phase flow, and the slag flow or the floss flow in which uneven bubbles are intermittently present in the refrigerant flow is accompanied by pressure pulsations and the expansion valve When the air flows into the valve, the expansion valve intermittently generates a loud noise.

In order to reduce the refrigerant flow noise emitted by the expansion valve, in the conventional indoor unit, the diameter of the expansion valve is made smaller than the inner diameter of the refrigerant pipe, or in the refrigerant pipe at a position upstream of the expansion valve. It has been tried to provide a branching / joining portion for once joining the refrigerant flow after branching the flow of refrigerant once.

According to this configuration, the flow of the refrigerant led to the expansion valve can shift from the slag flow or the flog flow to a more stable continuous flow, and the refrigerant flow noise caused by the gas-liquid two-phase flow can be reduced.

Japanese Patent Laid-Open No. 9-291166 Unexamined-Japanese-Patent No. 9-318198

However, for example, as when the number of revolutions of the compressor for delivering the refrigerant to the indoor unit decreases or when the operation shifts to the defrosting operation during the heating operation, the gas-liquid two-phase of the refrigerant is caused by the rapid pressure change in the refrigerant piping In the case of simply reducing the diameter of the expansion valve, it is difficult to suppress the refrigerant flow noise.

Furthermore, when the flow velocity of the refrigerant flowing through the refrigerant pipe is not sufficient, for example, when the defrosting operation is started during startup or heating operation of the multi-type air conditioning system, a branch junction located upstream of the expansion valve It is predicted that it will be difficult to mix the gas and liquid sufficiently.

An object of the present invention is to provide a multi-type air conditioning system having an indoor unit capable of quiet operation, which can reduce refrigerant flow noise generated when refrigerant flows into an expansion valve in a gas-liquid two-phase flow state. It is in.

According to the embodiment, the multi-type air conditioning system includes an outdoor unit having an outdoor heat exchanger for performing heat exchange between the refrigerant compressed by the compressor and the air, and the refrigerant having passed through the outdoor heat exchanger flowing in And a plurality of indoor units having an indoor heat exchanger for performing heat exchange between the expansion valve and the refrigerant decompressed by the expansion valve and the air, and a plurality of the indoor units connected in parallel to the outdoor unit. And a refrigerant pipe through which a refrigerant circulating between the outdoor unit and the indoor unit flows.

The refrigerant pipe positioned in the indoor unit has a plurality of capillaries at a location upstream of the expansion valve along the refrigerant flow direction, and the capillaries are connected in parallel to the refrigerant pipe. .

FIG. 1 is a circuit diagram showing a refrigeration cycle of a multi-type air conditioning system according to an embodiment. FIG. 2 is a perspective view of a wall-mounted indoor unit used in the multi-type air conditioning system. FIG. 3 is a cross-sectional view of the wall-mounted indoor unit. FIG. 4 is a plan view of the indoor unit showing the positional relationship between the indoor heat exchanger, the expansion valve, and the capillary part. FIG. 5 is a cross-sectional view of the expansion valve used in the multi-type air conditioning system. 6 is a plan view showing the capillary part of FIG. 4 in an enlarged manner.

Hereinafter, embodiments will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing a refrigeration cycle of a multi-type air conditioning system 1 used for, for example, a low-rise building or a store building. The multi-type air conditioning system 1 according to the present embodiment includes one outdoor unit 2, three indoor units 3, and a refrigerant pipe 4 through which a refrigerant circulating between the outdoor unit 2 and the indoor unit 3 flows.

Specifically, the outdoor unit 2 includes a hermetic compressor 5, a four-way valve 6, an outdoor heat exchanger 7, a first expansion valve 8 and an accumulator 9. As shown in FIG. 1, the discharge port of the hermetic compressor 5 is connected to the first port 6 a of the four-way valve 6. The second port 6 b of the four-way valve 6 is connected to the outdoor heat exchanger 7. The outdoor heat exchanger 7 is connected to the first expansion valve 8. Furthermore, the third port 6 c of the four-way valve 6 is connected to the accumulator 9. The accumulator 9 is connected to the suction port of the hermetic compressor 5 via a suction cup 10.

The three indoor units 3 are connected in parallel between the fourth port 6 d of the four-way valve 6 and the first expansion valve 8. Each indoor unit 3 has a second expansion valve 12 and an indoor heat exchanger 13. The second expansion valve 12 is interposed between the first expansion valve 8 and the indoor heat exchanger 13, and is connected to the first expansion valve 8 and the indoor heat exchanger 13. The indoor heat exchanger 13 is connected to the fourth port 6 d of the four-way valve 6.

When the multi-type air conditioning system 1 performs the cooling operation, the four-way valve 6 is switched so that the first port 6a communicates with the second port 6b and the third port 6c communicates with the fourth port 6d. When the cooling operation is started, the high temperature / high pressure gas phase refrigerant compressed by the hermetic compressor 5 is discharged to the refrigerant pipe 4. The high temperature and high pressure gas phase refrigerant is led to the outdoor heat exchanger 7 functioning as a condenser via the four-way valve 6.

The gas phase refrigerant led to the outdoor heat exchanger 7 is condensed by heat exchange with the outdoor air sent from the blower fan 11, and changes to a high pressure liquid phase refrigerant. The high-pressure liquid-phase refrigerant is decompressed in the process of passing through the first expansion valve 8 and then distributed to the three indoor units 3.

That is, the refrigerant that has passed through the first expansion valve 8 is decompressed again in the process of passing through the second expansion valve 12 of each indoor unit 3, and changes to a low pressure gas-liquid two-phase flow. The gas-liquid two-phase refrigerant is led to the indoor heat exchanger 13 which functions as an evaporator. The gas-liquid two-phase refrigerant introduced to the indoor heat exchanger 13 exchanges heat with indoor air sent from the blower fan 14 in the process of passing through the indoor heat exchanger 13.

As a result, the gas-liquid two-phase refrigerant takes heat from the air in the room and evaporates, and changes to a low-temperature low-pressure gas-phase refrigerant. The air passing through the indoor heat exchanger 13 is cooled by the latent heat of evaporation of the liquid-phase refrigerant, becomes cold air, and is blown into the room to be cooled.

The low-temperature low-pressure gas-phase refrigerant that has passed through the indoor heat exchanger 13 is sucked into the hermetic compressor 5 from the four-way valve 6 via the accumulator 9 and the suction cup 10. The gas phase refrigerant sucked into the hermetic compressor 5 is compressed again into a high temperature and high pressure gas phase refrigerant and discharged to the refrigerant pipe 4.

On the other hand, when the multi-type air conditioning system 1 performs a heating operation, the four-way valve 6 is switched so that the first port 6a communicates with the fourth port 6d and the second port 6b communicates with the third port 6c. When the heating operation is started, the high-temperature high-pressure gas-phase refrigerant compressed by the hermetic compressor 5 is distributed to the indoor heat exchangers 13 of the three indoor units 3 via the four-way valve 6, and condensed. In the process of passing through the indoor heat exchanger 13 functioning as a heat exchanger, heat is exchanged with the indoor air sent from the blower fan 14.

As a result, the gas phase refrigerant passing through the indoor heat exchanger 13 condenses by heat exchange with the air in the room, and changes to a high pressure liquid phase refrigerant. The air passing through the indoor heat exchanger 13 is heated by heat exchange with the gas phase refrigerant, becomes warm air, and is blown into the room to be heated.

The high-pressure liquid-phase refrigerant that has passed through the indoor heat exchanger 13 is decompressed in the process of passing through the second expansion valve 12 and the first expansion valve 8 and changes to a low-pressure gas-liquid two-phase flow. The gas-liquid two-phase refrigerant is led to the outdoor heat exchanger 7 functioning as an evaporator, and is evaporated here by heat exchange with the outdoor air sent from the blower 11 to change to a low temperature low pressure gas phase refrigerant . The low-temperature low-pressure gas-phase refrigerant having passed through the outdoor heat exchanger 7 is sucked from the four-way valve 6 into the hermetic compressor 5 via the accumulator 9 and the suction cup 10 as in the cooling operation.

If frost adheres to the outdoor heat exchanger 7 during the heating operation, the operation shifts to a defrosting operation for removing the frost. In the defrosting operation, the four-way valve 6 is switched from the heating operation to the cooling operation, and the blower fan 11 is stopped. As a result, the high temperature gas phase refrigerant compressed by the hermetic compressor 5 is led to the outdoor heat exchanger 7 and the frost adhering to the outdoor heat exchanger 7 is melted.

As shown in FIG. 2 and FIG. 3, the indoor unit 3 of the present embodiment is of a wall mounted type installed on the top of the wall W of the room R to be air conditioned, and has a housing 20 fixed to the wall W ing. The housing 20 is a box-shaped element having a front panel 21, a back panel 22 and left and right side panels 23. The housing 20 protrudes from the wall surface W into the room R to be air-conditioned, and extends laterally along the wall surface W.

Furthermore, the housing 20 has an inlet 24 and an outlet 25. The suction port 24 is opened on the top surface of the housing 20. The blower outlet 25 is opened at the lower surface of the housing 20. A horizontal louver 26 changes the blowing direction of the air-conditioned air in the vertical direction of the housing 20 in the air outlet 25 and a plurality of vertical louvers 27 changes the blowing direction of the air-conditioned air in the left-right direction of the housing 20. Only one is shown.

As shown in FIG. 3, the inside of the housing 20 is divided into a heat exchange chamber 28 and a pipe storage chamber 29. The heat exchange chamber 28 occupies a large area inside the housing 20, and the suction port 24 and the air outlet 25 are in communication with the heat exchange chamber 28. The piping storage chamber 29 is separated from the heat exchange chamber 28 by being surrounded by the cover 30. The pipe storage chamber 29 is offset to one side along the width direction of the housing 20 with respect to the heat exchange chamber 28 and is located behind the upper portion of the heat exchange chamber 28.

The indoor heat exchanger 13, the blower fan 14 and the filter 33 are accommodated in the heat exchange chamber 28. The indoor heat exchanger 13 is a plate-like element erected behind the front panel 21 and includes a plurality of cooling fins 34 and a plurality of heat transfer tubes 35 through which a refrigerant flows.

The cooling fins 34 extend in the height direction of the housing 20 and are arranged in a line at intervals in the width direction of the housing 20. The heat transfer tubes 35 are arranged at intervals in the height direction and the depth direction of the housing 20, and define a plurality of mutually independent refrigerant flow paths (paths). Furthermore, the heat transfer tube 35 is thermally connected to the cooling fin 34.

The blower fan 14 is disposed horizontally in the width direction of the housing 20 behind the indoor heat exchanger 13. Therefore, in the present embodiment, the indoor heat exchanger 13 is interposed between the blower fan 14 and the suction port 24 of the housing 20, and the blower outlet 25 having the horizontal louver 26 and the vertical louver 27 directly below the blower fan 14 is provided. It is located.

The filter 33 is removably supported by the heat exchange chamber 28 so as to face the front panel 21 and the suction port 24 of the housing 20. When the blower fan 14 starts operation, the air in the room R to be air conditioned is sucked into the heat exchange chamber 28 from the suction port 24. The air sucked into the heat exchange chamber 28 is filtered by the filter 33 and then led to the indoor heat exchanger 13. The air having passed through the indoor heat exchanger 13 is blown out into the room R to be air conditioned from the blowout port 25 after the blowout direction is changed by the vertical louvers 27 and the horizontal louvers 26.

As shown in FIGS. 3 and 4, the second expansion valve 12 and the liquid side pipe 37 are accommodated in the pipe accommodating chamber 29 of the housing 20. The liquid side pipe 37 constitutes a portion connecting the first expansion valve 8 of the refrigerant pipe 4 and the indoor heat exchanger 13 of the indoor unit 3.

As shown in FIGS. 4 and 5, the second expansion valve 12 is connected to an intermediate portion of the liquid side pipe 37. The second expansion valve 12 divides the liquid side piping 37 into an inlet pipe portion 37a and an outlet pipe portion 37b. The inlet pipe portion 37 a and the outlet pipe portion 37 b extend horizontally in the width direction of the housing 20 in the pipe housing chamber 29 and are arranged parallel to each other in the height direction of the housing 20. The downstream end of the inlet pipe portion 37a is bent upward at a right angle.

The second expansion valve 12 includes a valve body 40 and a drive unit 41. A refrigerant passage 42 is formed in the valve body 40. The refrigerant passage 42 includes a refrigerant introduction portion 42 a and a refrigerant discharge portion 42 b. The downstream end of the inlet pipe portion 37a of the liquid side pipe 37 is connected to the refrigerant introducing portion 42a. The upstream end of the outlet pipe portion 37b of the liquid side pipe 37 is connected to the refrigerant lead-out portion 42b.

Furthermore, the refrigerant introduction part 42 a and the refrigerant lead-out part 42 b cross each other in the valve main body 40. A valve seat 43 is formed at the intersection of the refrigerant introduction portion 42a and the refrigerant lead-out portion 42b.

The valve main body 40 of the present embodiment has a needle support portion 44 which is protruded toward the opposite side to the refrigerant lead-out portion 42 b. A needle insertion hole 45 is formed inside the needle support portion 44. The needle insertion hole 45 is located coaxially with the refrigerant lead-out portion 42b.

A needle 47 as a valve body is axially slidably inserted in the needle insertion hole 45. The needle 47 is supported by the needle support 44 so as to be movable between a fully closed position and an open position.

In the fully closed position, the tapered head portion 47a located at one end along the axial direction of the needle 47 is seated on the valve seat 43, and cuts off the communication between the refrigerant introducing portion 42a and the refrigerant discharging portion 42b. In the open position, the head 47 a of the needle 47 separates from the valve seat 43, and the area of the passage between the head 47 a and the valve seat 43 is increased or decreased. Thus, the flow rate of the refrigerant flowing from the refrigerant introduction portion 42a toward the refrigerant lead-out portion 42b is controlled.

The drive portion 41 of the second expansion valve 12 is an element for moving the needle 47 in the axial direction, and includes a motor 48 and an electromagnet 49 as main elements. The motor 48 is fixed to the outer peripheral surface of the cylindrical rotor portion 51 screwed to the outer peripheral surface of the needle support portion 44, the cylindrical spacer 52 fitted to the outer peripheral surface of the rotor portion 51, and the spacer 52 And an electromagnet 53. The tip of the rotor portion 51 is connected to an end 47 b of the needle 47 opposite to the head 47 a via an engaging element 54.

Furthermore, the motor 48 is covered by the case 55 together with the needle support 44. The electromagnet 49 surrounds the electromagnet 53 from the outside of the case 55.

The rotor portion 51 of the motor 48 rotates in accordance with the amount of energization of the electromagnet 49. The rotor portion 51 is screwed into the needle support portion 44, and thus moves in the axial direction of the needle support portion 44 by rotation. The motion of the rotor portion 51 is transmitted to the needle 47, so that the needle 47 linearly moves between the fully closed position and the open position. Thus, the flow rate control of the refrigerant flowing from the refrigerant introduction portion 42a toward the refrigerant lead-out portion 42b is performed.

As shown in FIGS. 4 and 6, a capillary section 60 is provided in the middle of the inlet pipe section 37a of the liquid side pipe 37. The capillary unit 60 is positioned upstream of the second expansion valve 12 along the flow direction of the refrigerant during the cooling operation.

The capillary unit 60 includes two

capillaries

61 a and 61 b, a branch pipe 62 and a merging pipe 63. The

capillaries

61a and 61b are each formed of a straight pipe having a predetermined length L and an inner diameter d2. In the present embodiment, the length L of the

capillaries

61a and 61b is set to 80 mm, and the inner diameter d2 of the

capillaries

61a and 61b is set to 2 mm.

The branch pipe portion 62 includes one first connection port 64 to which the liquid side piping 37 is connected, and a pair of

second connection ports

65 a and 65 b branched into two from the first connection port 64. Have. The merging pipe portion 63 includes one third connection port 66 to which the inlet pipe portion 37a is connected, and a pair of

fourth connection ports

67a and 67b branched into two from the third connection port 66. Have.

One capillary 61 a is bridged between the second connection port 65 a of the branch pipe portion 62 and the fourth connection port 67 a of the merging pipe portion 63. The other capillary 61 b is bridged between the second connection port 65 b of the branch pipe portion 62 and the fourth connection port 67 b of the junction pipe portion 63. Therefore, the

capillaries

61a and 61b are arranged in parallel to the inlet pipe portion 37a of the liquid side pipe 37 so as to be parallel to each other with an interval in the height direction of the housing 20, for example.

In the present embodiment, the inner diameter d2 of each of the

capillaries

61a and 61b is set equal to or larger than the diameter d1 of the refrigerant introduction portion 42a of the second expansion valve 12, and the inlet pipe of the liquid side pipe 37 The diameter is set smaller than the inner diameter d3 of the portion 37a. Furthermore, when d1, d2 and d3 are n, the number of

capillaries

61a and 61b is
d1 <d2 × n <d3
It is desirable to satisfy

As shown in FIG. 4, the outlet pipe portion 37 b of the liquid side pipe 37 is connected to the plurality of branch pipes 71 via the distributor 70. The branch pipe 71 corresponds to the number of the plurality of refrigerant flow paths (passes) that the indoor heat exchanger 13 has, and the branch pipe 71 is connected to the inlet of the refrigerant flow path.

Furthermore, the outlets of the plurality of refrigerant flow paths (paths) of the indoor heat exchanger 13 are connected to the gas side pipe 73 via the header 72 after being merged into one by the header 72. The gas side pipe 73 constitutes a portion connecting the indoor heat exchanger 13 of the indoor unit 3 and the fourth port 6 d of the four-way valve 6 in the refrigerant pipe 4.

In a state where the multi-type air conditioning system 1 is in a cooling operation, the refrigerant having passed through the first expansion valve 8 has a flow mode in which nonuniform bubbles are intermittently included in the flow, for example, like a slag flow. If the refrigerant passes through the gap between the head 47 a of the needle 47 of the second expansion valve 12 and the valve seat 43, unpleasant refrigerant flow noise is generated.

In the indoor unit 3 of the present embodiment, a capillary section 60 having two

capillaries

61a and 61b is provided on the upstream side along the flow direction of the refrigerant than the second expansion valve 12. Therefore, when the refrigerant of gas-liquid two-phase flow including non-uniform bubbles reaches the capillary section 60, the refrigerant is branched into two flows by the branch pipe section 62 and then flows into the

capillaries

61a and 61b.

Since the inner diameter d2 of the

capillaries

61a and 61b is smaller than the inner diameter d3 of the inlet pipe portion 37a of the liquid side pipe 37, the flow velocity of the branched refrigerant is increased by the throttling effect of the

capillaries

61a and 61b.

As a result, the flow of the refrigerant passing through the

capillaries

61a, 61b is changed from the slag flow to the stable flow pattern of the spray flow. That is, as the flow velocity increases, the flow of the refrigerant becomes continuous, and the intermittent flow of the refrigerant that is a cause of the refrigerant flow noise is eliminated.

Furthermore, the refrigerant transferred to the continuous spray flow in the process of passing through the

capillaries

61a and 61b merges with each other in the merging pipe portion 63. Thereby, the mixing of the gas and liquid contained in the refrigerant is promoted, and the bubbles contained in the refrigerant from the merging pipe portion 63 to the second expansion valve 12 form a uniform flow of the subdivided refrigerant. it can.

As a result, at the time when the refrigerant reaches near the gap between the head 47 a of the needle 47 of the second expansion valve 12 and the valve seat 43, fine refrigerant is continuously continuous in the liquid. It is possible to shift to a flow mode in which the refrigerant is mixed, and to minimize the pressure change when the refrigerant passes through the gap.

Therefore, for example, when the multi-type air conditioning system 1 starts up, even when the flow rate of the gas-liquid two-phase flow refrigerant flowing through the liquid side pipe 37 is not sufficient, such as when heating operation shifts to defrosting operation, the indoor unit 3 The refrigerant flow noise emitted by the second expansion valve 12 can be efficiently reduced, and silent operation is possible.

Moreover, in this embodiment, the bore diameter of the second expansion valve 12 is d1, the inner diameter of the

capillaries

61a and 61b is d2, the inner diameter of the inlet pipe portion 37a of the liquid side pipe 37 is d3, and the number of the

capillaries

61a and 61b is n. When you
d1 <d2 × n <d3
Meet the relationship.

As a result, the sum of the cross sectional areas of the passages of the

capillaries

61a and 61b can be sufficiently secured with respect to the diameter d1 of the second expansion valve 12, and unnecessary pressure loss when the refrigerant passes through the

capillaries

61a and 61b. It can prevent.

In addition, since the inner diameter d2 of each of the

capillaries

61a and 61b is smaller than the inner diameter d3 of the inlet pipe portion 37a of the liquid side pipe 37, the refrigerant throttling effect by the

capillaries

61a and 61b can be sufficiently exhibited. Therefore, the flow velocity of the refrigerant passing through the

capillaries

61a and 61b is increased, which is advantageous in making the flow of the refrigerant introduced to the second expansion valve 12 more uniform.

While certain embodiments of the present invention have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and the gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

For example, the number of outdoor units of the multi-type air conditioning system is not limited to one, and may be two or three, and the number of outdoor units and indoor units is not particularly limited.

Furthermore, although the number of capillaries is two in the above embodiment, the number of capillaries is not limited. At the same time, the inner diameters of the capillaries do not have to be identical to each other, and the inner diameters of a plurality of capillaries may be made different from each other as long as the diameter is smaller than the inlet pipe portion of the liquid side piping.

In addition, the capillary is not limited to being arranged horizontally, and for example, the capillary may be erected in the housing if a sufficient space can be secured in the housing.

DESCRIPTION OF SYMBOLS 1 ... multi type air conditioning system, 2 ... outdoor unit, 3 ... indoor unit, 4 ... refrigerant piping, 5 ... compressor (sealed type compressor), 7 ... outdoor heat exchanger, 12 ... expansion valve (2nd expansion valve 13)

indoor heat exchanger

61a, 61b capillary.

Claims

An outdoor unit having an outdoor heat exchanger for performing heat exchange between the refrigerant compressed by the compressor and the air;
The expansion valve into which the refrigerant that has passed through the outdoor heat exchanger flows in, and the indoor heat exchanger that exchanges heat between the refrigerant and the air whose pressure has been reduced by the expansion valve, and is exposed to the room to be air conditioned Multiple indoor units to be
A multi-type air conditioning system comprising: a plurality of indoor units connected in parallel to the outdoor unit; and a refrigerant pipe through which a refrigerant circulating between the outdoor unit and the indoor unit flows.
The refrigerant pipe located in the indoor unit has a plurality of capillaries at a location upstream of the expansion valve along the flow direction of the refrigerant, and the capillary is connected in parallel to the refrigerant pipe. Type air conditioning system.
The multi-type air conditioning system according to claim 1, wherein the capillary is a straight pipe having a predetermined total length, and the flow velocity of the refrigerant flowing toward the expansion valve is increased.
The branch pipe portion for connecting between the upstream end of the capillary and the refrigerant pipe, and the junction pipe portion for connecting between the downstream end of the capillary and the refrigerant pipe. The multi-type air conditioning system according to 2.
The multi-type air conditioning system according to claim 2, wherein the indoor unit is a wall hanging type exposed in a room to be air conditioned, and the plurality of capillaries are horizontally arranged at intervals.
Assuming that the diameter of the expansion valve is d1, the inner diameter of the capillary is d2, the inner diameter of the refrigerant pipe connected to the branch pipe is d3, and the number of capillaries is n,
d1 <d2 × n <d3
The multi-type air conditioning system according to claim 3, which satisfies the following relationship:
During the cooling operation and the defrosting operation, the flow of the refrigerant passing through the outdoor heat exchanger is branched into the plurality of capillaries, and the expansion valve is performed in a state where the refrigerant passing through the plurality of capillaries merges with each other The multi-type air conditioning system according to claim 1, wherein
An expansion valve,
A refrigerant pipe for guiding the refrigerant heat-exchanged by the outdoor unit to the expansion valve;
An indoor heat exchanger for exchanging heat with the refrigerant decompressed by the expansion valve;
An indoor unit provided with a plurality of capillaries connected in parallel to the refrigerant pipe at a location on the refrigerant pipe upstream of the expansion valve along the flow direction of the refrigerant.
The indoor unit according to claim 7, wherein the capillary is a straight pipe having a predetermined total length, and the flow velocity of the refrigerant flowing toward the expansion valve is increased.
The branch pipe portion for connecting between the upstream end of the capillary and the refrigerant pipe, and the junction pipe portion for connecting between the downstream end of the capillary and the refrigerant pipe. The indoor unit described in 8
Assuming that the diameter of the expansion valve is d1, the inner diameter of the capillary is d2, the inner diameter of the refrigerant pipe connected to the branch pipe is d3, and the number of capillaries is n,
d1 <d2 × n <d3
The indoor unit according to claim 9, satisfying the following relationship: