Technical Field
[0001] Embodiments described herein relate generally to a multi-type air-conditioning system
and indoor unit.
Background Art
[0002] 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 the refrigerant to be supplied
to each indoor unit changes from moment to moment depending on the room temperature,
the usage state or the like of the indoor units. Accordingly, depending on the state
of the refrigerant flowing into the plurality of indoor units, there is a possibility
of the refrigerant to be supplied from the outdoor unit to the indoor units being
changed from the liquid-phase flow state to the gas-liquid two-phase flow state.
[0003] It is known that when a refrigerant of the gas-liquid two-phase flow flows into an
expansion valve of the indoor unit, a harsh refrigerant flow sound is generated. That
is, the refrigerant flow sound is dependent on the flow regime of the gas-liquid two-phase
flow and, when a slug flow or froth flow caused when non-uniform bubbles intermittently
exist in the flow of the refrigerant comes into the expansion valve while being accompanied
by pressure pulsation, a large unusual sound is intermittently generated from the
expansion valve.
[0004] In order to reduce the refrigerant flow sound generated from the expansion valve,
in the conventional indoor unit, making the bore diameter of the expansion valve less
than the inner diameter of the refrigerant piping or once branching the flow of the
refrigerant into a plurality of flows, and providing a branch confluence part at which
the branched flows are thereafter made to join together again at a position of the
refrigerant piping located on the upstream side of the expansion valve is tentatively
executed.
[0005] According to this configuration, it is possible to make the flow of the refrigerant
to be guided to the expansion valve shift from the slug flow or froth flow to a more
stable and continuous flow and reduce the refrigerant flow sound attributable to the
gas-liquid two-phase flow.
Citation List
Patent Literatures
Summary of Invention
Technical Problem
[0007] However, as in the case where, for example, the rotational speed of the compressor
configured to send forth the refrigerant to the indoor units lowers or where the operation
is shifted to a defrosting operation while a heating operation is carried out, when
a gas-liquid two-phase state of the refrigerant is caused by an abrupt pressure change
inside the refrigerant piping, it is undeniable that it becomes difficult to suppress
the refrigerant flow sound by only making the bore diameter of the expansion valve
smaller as a countermeasure.
[0008] Furthermore, for example, as in the case where the multi-type air-conditioning system
is started or as in the case where the operation is shifted to the defrosting operation
while the heating operation is carried out, when the flow rate (velocity) of the refrigerant
flowing through the refrigerant piping is not sufficient, it can be predicted that
it may become difficult to sufficiently mix the gas and liquid at the bifurcation
confluence part located on the upstream side of the expansion valve.
[0009] An embodiment described herein aims to obtain a multi-type air-conditioning system
capable of reducing a refrigerant flow sound caused when a refrigerant flows into
an expansion valve in a gas-liquid two-phase flow state, and including indoor units
capable of silent operations.
Means for Solving the Problem
[0010] According to an embodiment, a multi-type air-conditioning system includes an outdoor
unit including an outdoor heat exchanger, a plurality of indoor units each including
an expansion valve into which the refrigerant passing through the outdoor heat exchanger
flows and an indoor heat exchanger configured to cause heat exchange to be carried
out between the refrigerant decompressed by the expansion valve and air, and refrigerant
piping which connects the plurality of indoor units in parallel to the outdoor unit,
and through which the refrigerant flows.
[0011] Part of the refrigerant piping positioned inside each of the indoor units includes
a plurality of capillaries at a position on the upstream side of the expansion valve
in the flow direction of the refrigerant, and the capillaries are connected in parallel
to the refrigerant piping.
Brief Description of Drawings
[0012]
FIG. 1 is a circuit diagram showing a refrigerating cycle of a multi-type air-conditioning
system according to an embodiment.
FIG. 2 is a perspective view of a wall-mounted indoor unit to be used for 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 positional relationships among an
indoor heat exchanger, expansion valve, and capillary section.
FIG. 5 is a cross-sectional view of the expansion valve to be used for the multi-type
air-conditioning system.
FIG. 6 is a plan view showing the capillary section of FIG. 4 in an enlarging manner.
[0013] Mode for Carrying Out the Invention Hereinafter, an embodiment of the present invention
will be described below with reference to the accompanying drawings.
[0014] FIG. 1 is a circuit diagram showing a refrigerating cycle of a multi-type air-conditioning
system 1 to be used for, for example, a medium low story building or store building.
The multi-type air-conditioning system 1 according to this embodiment is provided
with one outdoor unit 2, three indoor units 3, and refrigerant piping 4 through which
a refrigerant circulating among the outdoor unit 2 and indoor units 3 flows.
[0015] More specifically, the outdoor unit 2 includes a hermetic type compressor 5, four-way
valve 6, outdoor heat exchanger 7, first expansion valve 8, and accumulator 9. As
shown in FIG. 1, a discharge port of the hermetic type compressor 5 is connected to
a first port 6a of the four-way valve 6. A second port 6b 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, a third port 6c of the four-way valve
6 is connected to the accumulator 9. The accumulator 9 is connected to an admission
port of the hermetic type compressor 5 through a suction cup 10.
[0016] The three indoor units 3 are connected in parallel between a fourth port 6d of the
four-way valve 6 and first expansion valve 8. Each indoor unit 3 includes a second
expansion valve 12 and indoor heat exchanger 13. The second expansion valve 12 is
interposed between the first expansion valve 8 and indoor heat exchanger 13 and is
connected to the first expansion valve 8 and indoor heat exchanger 13. The indoor
heat exchanger 13 is connected to the fourth port 6d of the four-way valve 6.
[0017] When the multi-type air-conditioning system 1 is to carry out a cooling operation,
the four-way valve 6 is switched in such a manner that the first port 6a communicates
with second port 6b and third port 6c communicates with fourth port 6d. When the cooling
operation is started, a high-temperature/high-pressure gas-phase refrigerant compressed
by the hermetic type compressor 5 is discharged into the refrigerant piping 4. The
high-temperature/high-pressure gas-phase refrigerant is guided to the outdoor heat
exchanger 7 functioning as a condenser through the four-way valve 6.
[0018] The gas-phase refrigerant which has been guided to the outdoor heat exchanger 7 is
condensed by heat exchange with the outdoor air sent from a blast fan 11 and is changed
into 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
is thereafter distributed to the three indoor units 3.
[0019] That is, the refrigerant passing through the first expansion valve 8 is decompressed
again in the process of passing through the second expansion valves 12 of the indoor
units 3 and is changed into a low-pressure gas-liquid two-phase flow refrigerant.
The gas-liquid two-phase refrigerant is guided to the indoor heat exchangers 13 functioning
as evaporators. The gas-liquid two-phase refrigerant which has been guided to the
indoor heat exchangers 13 carries out heat exchange with the indoor air sent from
blast fans 14 in the process of passing through the indoor heat exchangers 13.
[0020] As result, the gas-liquid two-phase refrigerant carries out heat removal from the
indoor air to thereby evaporate and changes into a low-temperature/low-pressure gas-phase
refrigerant. The air passing through the indoor heat exchangers 13 is cooled by the
latent heat of vaporization of the liquid-phase refrigerant, is made the cool air,
and is sent into the rooms to be cooled.
[0021] The low-temperature/low-pressure gas-phase refrigerant passing through the indoor
heat exchangers 13 is sucked into the hermetic type compressor 5 from the four-way
valve 6 through the accumulator 9 and suction cup 10. The gas-phase refrigerant which
has been sucked into the hermetic type compressor 5 is again compressed into a high-temperature/high-pressure
gas-phase refrigerant and is discharged into the refrigerant piping 4.
[0022] On the other hand, when the multi-type air-conditioning system 1 is to carry out
a heating operation, the four-way valve 6 is switched in such a manner that the first
port 6a communicates with the fourth port 6d and second port 6b communicates with
third port 6c. When the heating operation is started, the high-temperature/high-pressure
gas-phase refrigerant compressed by the hermetic type compressor 5 is distributed
to the indoor heat exchangers 13 of the three indoor units 3 and carries out heat
exchange with the indoor air sent from the blast fans 14 in the process of passing
through the indoor heat exchangers 13 functioning as condensers.
[0023] As a result, the gas-phase refrigerant passing through the indoor heat exchangers
13 condenses by carrying out heat exchange with the indoor air and changes into a
high-pressure liquid-phase refrigerant. The air passing through the indoor heat exchangers
13 is heated by the heat exchange with the gas-phase refrigerant, is made the warm
air, and is sent into the rooms to be heated.
[0024] The high-pressure liquid-phase refrigerant passing through the indoor heat exchangers
13 is decompressed in the process of passing through the second expansion valves 12
and first expansion valve 8 and is changed into a low-pressure gas-liquid two-phase
flow refrigerant. The gas-liquid two-phase refrigerant is guided to the outdoor heat
exchanger 7 functioning as an evaporator, evaporates here by heat exchange with the
outdoor air sent from the blast fan 11, and changes into a low-temperature/low-pressure
gas-phase refrigerant. The low-temperature/low-pressure gas-phase refrigerant passing
through the outdoor heat exchanger 7 is, as in the case of the cooling operation,
sucked into the hermetic type compressor 5 from the four-way valve 6 through the accumulator
9 and suction cup 10.
[0025] When frost forms on the outdoor heat exchanger 7 during the heating operation, the
operation is shifted to the defrosting operation of removing the frost. In the defrosting
operation, the four-way valve 6 is switched from the state of the heating operation
to the state of the cooling operation and the blast fan 11 is stopped. Thereby, the
high-temperature gas-phase refrigerant compressed by the hermetic type compressor
5 is guided to the outdoor heat exchanger 7 and melts the frost adhering to the outdoor
heat exchanger 7.
[0026] As shown in FIG. 2 and FIG. 3, the indoor unit 3 of this embodiment is a wall-mounted
type unit installed on the upper part of the wall surface W of a room R to be air-conditioned
and includes a housing 20 fixed to the wall surface W. The housing 20 is a box-shaped
element including a front panel 21, rear panel 22, and side panels 23 on the right
and left sides. The housing 20 is protruded from the wall surface W toward the inside
of the room R to be air-conditioned and extends in the lateral directions along the
wall surface W.
[0027] Furthermore, the housing 20 includes a suction opening 24 and blowout opening 25.
The suction opening 24 is opened at the top surface of the housing 20. The blowout
opening 25 is opened at the lower surface of the housing 20. In the blowout opening
25, a horizontal louver 26 configured to change the blowout direction of the air-conditioned
air to the vertical directions of the housing 20 and a plurality of vertical louvers
27 (only one of them is shown) configured to change the blowout direction of the air-conditioned
air to the lateral directions of the housing 20 are arranged.
[0028] As shown in FIG. 3, the inside of the housing 20 is divided into a heat-exchanging
chamber 28 and piping-accommodating chamber 29. The heat-exchanging chamber 28 occupies
a large part of the interior of the housing 20 and the suction opening 24 and blowout
opening 25 are made to communicate with the heat-exchanging chamber 28. The piping-accommodating
chamber 29 is surrounded by a cover 30 to thereby be separated from the heat-exchanging
chamber 28. The piping-accommodating chamber 29 is shifted to one side of the housing
20 in the width direction of the housing 20 and is positioned at the upper rear part
of the heat-exchanging chamber 28.
[0029] The aforementioned indoor heat exchanger 13, blast fan 14, and a filter 33 are accommodated
in the heat-exchanging chamber 28. The indoor heat exchanger 13 is a plate-like element
made to vertically rise behind the front panel 21 and is provided with a plurality
of cooling fins 34 and a plurality of heat exchanger tubes 35 through which the refrigerant
flows.
[0030] 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 exchanger
tubes 35 are arranged at intervals in both the height direction and depth direction
of the housing 20 and define a plurality of refrigerant paths independent of each
other. Furthermore, the heat exchanger tubes 35 are thermally connected to the cooling
fins 34.
[0031] The blast fan 14 is horizontally arranged in the width direction of the housing 20
behind the indoor heat exchanger 13. Accordingly, in this embodiment, the indoor heat
exchanger 13 is interposed between the blast fan 14 and suction opening 24 of the
housing 20, and blowout opening 25 including the horizontal louver 26 and vertical
louvers 27 is positioned directly below the blast fan 14.
[0032] The filter 33 is detachably supported on the heat-exchanging chamber 28 in such a
manner as to be opposed to the front panel 21 of the housing 20 and suction opening
24 thereof. When the blast fan 14 starts an operation, the air inside the room R to
be air-conditioned is sucked into the heat-exchanging chamber 28 from the suction
opening 24. The air which has been sucked into the heat-exchanging chamber 28 is filtered
by the filter 33 and is thereafter guided to the indoor heat exchanger 13. The air
passing through the indoor heat exchanger 13 is changed in the blowout direction thereof
by the vertical louvers 27 and horizontal louver 26 and is thereafter discharged from
the blowout opening 25 into the inside of the room R to be air-conditioned.
[0033] As shown in FIG. 3 and FIG. 4, the aforementioned second expansion valve 12 and liquid-side
piping 37 are accommodated in the piping-accommodating chamber 29 of the housing 20.
The liquid-side piping 37 constitutes a part of the refrigerant piping 4, the part
connecting between the first expansion valve 8 and indoor heat exchanger 13 of each
indoor unit 3.
[0034] As shown in FIG. 4 and FIG. 5, the second expansion valve 12 is connected to an intermediate
part of the liquid-side piping 37. The second expansion valve 12 divides the liquid-side
piping 37 into an entrance pipe section 37a and exit pipe section 37b. The entrance
pipe section 37a and exit pipe section 37b horizontally extend in the width direction
of the housing 20 inside the piping-accommodating chamber 29 and are arranged horizontally
in parallel to each other with a gap held between them in the height direction of
the housing 20. A downstream end of the entrance pipe section 37a is upwardly bent
at right angles.
[0035] The second expansion valve 12 is provided with a valve main body 40 and drive section
41. Inside the valve main body 40, a refrigerant path 42 is formed. The refrigerant
path 42 includes a refrigerant introductory section 42a and refrigerant lead-out section
42b. A downstream end of the entrance pipe section 37a of the liquid-side piping 37
is connected to the refrigerant introductory section 42a. An upstream end of the exit
pipe section 37b of the liquid-side piping 37 is connected to the refrigerant lead-out
section 42b.
[0036] Furthermore, the refrigerant introductory section 42a and refrigerant lead-out section
42b are made to intersect each other inside the valve main body 40. At a part at which
the refrigerant introductory section 42a and refrigerant lead-out section intersect
each other, a valve seat 43 is formed.
[0037] The valve main body 40 of this embodiment includes a needle supporting section 44
protruded toward the opposite side of the refrigerant lead-out section 42b. A needle
insertion hole 45 is formed inside the needle supporting section 44. The needle insertion
hole 45 is positioned coaxially with the refrigerant lead-out section 42b.
[0038] A needle 47 functioning as a valve body is inserted into the needle insertion hole
45 in such a manner as to be slidable in the axial direction. The needle 47 is supported
by the needle supporting section 44 in such a manner as to be movable between the
fully-closed position and opened position.
[0039] At the fully-closed position, a head section 47a having a tapered shape and positioned
at one end of the needle 47 in the axial direction thereof is seated in the valve
seat 43 and shuts off the communication between the refrigerant introductory section
42a and refrigerant lead-out section 42b. At the opened position, the head section
47a of the needle 47 separates from the valve seat 43 and the cross-sectional area
of the flow path between the head section 47a and valve seat 43 is increased/decreased.
Thereby, the flow rate of the refrigerant flowing from the refrigerant introductory
section 42a toward the refrigerant lead-out section 42b is controlled.
[0040] The drive section 41 of the second expansion valve 12 is an element configured to
move the needle 47 in the axial direction, and is provided with a motor 48 and electromagnet
49 as main constituents. The motor 48 includes a cylindrical rotor section 51 screwed
onto the outer circumferential surface of the needle supporting section 44, cylindrical
spacer 52 fitted onto the outer circumferential surface of the rotor section 51, and
electromagnet 53 fixed to the outer circumferential surface of the spacer 52. The
tip of the rotor section 51 is coupled to the end 47b of the needle 47 on the opposite
side of the head section 47a through an engaging piece 54.
[0041] Furthermore, the motor 48 is covered with a case 55 together with the needle supporting
section 44. The electromagnet 49 surrounds the electromagnet 53 from outside the case
55.
[0042] The rotor section 51 of the motor 48 rotates according to the amount of power fed
to the electromagnet 49. The rotor section 51 is screwed onto the needle supporting
section 44, and hence the rotor section 51 rotates to thereby move in the axial direction
of the needle supporting section 44. The movement of the rotor section 51 is transmitted
to the needle 47, whereby the needle 47 linearly moves between the fully-closed position
and opened position. Thereby, flow rate control of the refrigerant flowing from the
refrigerant introductory section 42a toward the refrigerant lead-out section 42b is
carried out.
[0043] As shown in FIG. 4 and FIG. 6, a capillary section 60 is provided in the middle of
the entrance pipe section 37a of the liquid-side piping 37. The capillary section
60 is positioned on the upstream side of the second expansion valve 12 in the flow
direction of the refrigerant at the time of the cooling operation.
[0044] The capillary section 60 is provided with two capillaries 61a and 61b, bifurcation
pipe section 62, and confluence pipe section 63. Each of the capillaries 61a and 61b
is constituted of a straight pipe previously having a predetermined length L and inner
diameter d2. In this embodiment, the length L of each of the capillaries 61a and 61b
is set to 80 mm, and inner diameter d2 of each of the capillaries 61a and 61b is set
to 2 mm.
[0045] The bifurcation pipe section 62 includes one first connection port 64 to which the
liquid-side piping 37 is connected and a pair of second connection ports 65a and 65b
bifurcated from the first connection port 64. The confluence pipe section 63 includes
one third connection port 66 to which the entrance pipe section 37a is connected and
a pair of fourth connection ports 67a and 67b bifurcated from the third connection
port 66.
[0046] The one capillary 61a is stretched between the second connection port 65a of the
bifurcation pipe section 62 and fourth connection port 67a of the confluence pipe
section 63. The other capillary 61b is stretched between the second connection port
65b of the bifurcation pipe section 62 and fourth connection port 67b of the confluence
pipe section 63. Accordingly, the capillaries 61a and 61b are arranged in parallel
to the entrance pipe section 37a of the liquid-side piping 37 in such a manner that
the capillaries 61a and 61b are parallel to each other with a gap held between them
in, for example, the height direction of the housing 20.
[0047] In this embodiment, the inner diameter d2 of each of the capillaries 61a and 61b
is set to a value equal to or greater than the inner diameter d1 of the refrigerant
introductory section 42a of the second expansion valve 12, and is set to a value less
than the inner diameter d3 of the entrance pipe section 37a of the liquid-side piping
37. Furthermore, it is desirable that the inner diameters d1, d2, and d3 should satisfy
the following relationship when the number of the capillaries 61a and 61b is assumed
to be n.

[0048] As shown in FIG. 4, the exit pipe section 37b of the liquid-side piping 37 is connected
to a plurality of branch pipes 71 through a distributor 70. The branch pipes 71 correspond
to the number of the plurality of refrigerant flow paths included in the indoor heat
exchanger 13, and the branch pipes 71 are connected to entrances of the refrigerant
flow paths.
[0049] Furthermore, exits of the plurality of refrigerant flow paths of the indoor heat
exchanger 13 are made to join together to form one single flow path at the header
72 and the one flow path is connected to the gas-side piping 73 through the header
72. The gas-side piping 73 constitutes a part of the aforementioned refrigerant piping
4, the part connecting between the indoor heat exchanger 13 of each indoor unit 3
and fourth port 6d of the four-way valve 6.
[0050] In the state where the multi-type air-conditioning system 1 is cooling-operated,
assuming that the refrigerant passing through the first expansion valve 8 is of a
flow regime such as a slug flow caused when non-uniform bubbles intermittently exist
in the flow of the refrigerant, when the refrigerant passes through the gap of the
second expansion valve 12 between the head section 47a of the needle 47 and valve
seat 43, an unpleasant refrigerant flow sound is generated.
[0051] In the indoor unit 3 of this embodiment, the capillary section 60 including the two
capillaries 61a and 61b is provided on the upstream side of the second expansion valve
12 in the flow direction of the refrigerant. Accordingly, when the refrigerant of
a gas-liquid two-phase flow containing therein non-uniform bubbles reaches the capillary
section 60, the refrigerant is bifurcated into two flows at the bifurcation pipe section
62 and thereafter flows into the capillaries 61a and 61b.
[0052] The inner diameter d2 of each of the capillaries 61a and 61b is less than the inner
diameter d3 of the entrance pipe section 37a of the liquid-side piping 37, and hence
the flow velocity of the refrigerant bifurcated into the two flows is enhanced by
the throttling effect achieved by the capillaries 61a and 61b.
[0053] Thereby, the flow of the refrigerant passing through the capillaries 61a and 61b
is changed from the slug flow into a flow regime of a stable spray flow. That is,
with an increase in the flow velocity, the flow of the refrigerant becomes continuous,
and the intermittent flow of the refrigerant causing an occurrence factor of the refrigerant
flow sound is dissolved.
[0054] Furthermore, the bifurcated flows of the refrigerant which have shifted to the continuous
spray flows in the process of passing through the capillaries 61a and 61b join together
at the confluence pipe section 63. Thereby, mixing of the gas and liquid contained
in the refrigerant is promoted, and it is possible to form a uniform flow of the refrigerant
in which the bubbles contained in the refrigerant flowing from the confluence pipe
section 63 toward the second expansion valve 12 are fractionated.
[0055] As a result, at the point of time at which the refrigerant reaches a position in
the vicinity of the gap of the second expansion valve 12 between the head section
47a of the needle 47 and valve seat 43, the refrigerant shifts to such a flow regime
that minute bubbles uniformly and continuously exist in the liquid in the state where
the bubbles are intermingled with the refrigerant, and it is possible to limit the
pressure change at the time when the refrigerant passes through the aforementioned
gap to a small change.
[0056] Accordingly, as in the case where for example, the multi-type air-conditioning system
1 is started or the operation is shifted from the heating operation to the defrosting
operation, even when the flow velocity of the refrigerant of the gas-liquid two-phase
flow flowing through the liquid-side piping 37 is not sufficient, it is possible to
efficiently reduce the refrigerant flow sound generated from the second expansion
valve 12 of the indoor unit 3, and a silent operation is enabled.
[0057] Moreover, in this embodiment, when the bore diameter of the second expansion valve
12 is d1, inner diameter of each of the capillaries 61a and 61b is d2, inner diameter
of the entrance pipe section 37a of the liquid-side piping 37 is d3, and the number
of the capillaries 61a and 61b is n, the following relationship is satisfied.

[0058] Thereby, it is possible to sufficiently secure the total sum of the path cross-sectional
areas of the capillaries 61a and 61b with respect to the bore diameter d1 of the second
expansion valve 12, and prevent the unnecessary pressure loss at the time when the
refrigerant passes through the capillaries 61a and 61b from occurring.
[0059] In addition, the inner diameter d2 of each of the capillaries 61a and 61b is less
than the inner diameter d3 of the entrance pipe section 37a of the liquid-side piping
37, and hence it is possible to make the capillaries 61a and 61b sufficiently exert
the refrigerant throttling effect. Accordingly, the flow velocity of the refrigerant
passing through the capillaries 61a and 61b is enhanced, this being convenient for
further uniformizing the flow of the refrigerant to be guided to the second expansion
valve 12.
[0060] While certain embodiments have been described, these embodiments have been presented
by way of example only, and are not intended to limit the scope of the inventions.
Indeed, the novel embodiments described herein may be embodied in a variety of other
forms; furthermore, various omissions, substitutions and changes in the form of the
embodiments described herein may be made without departing from the spirit of the
inventions. The accompanying claims and their equivalents are intended to cover such
forms or modifications as would fall within the scope and spirit of the inventions.
[0061] For example, the outdoor unit of the multi-type air-conditioning system is not limited
to one unit, two or three outdoor units may be provided and, there is no particular
restriction on the number of the outdoor units or indoor units.
[0062] Furthermore, in the embodiment described above, although the number of the capillaries
is two, there is no restriction also on the number of the capillaries. In addition
to the above, the inner diameters of the capillaries need not be equal to each other
and, the inner diameters of a plurality of capillaries may be made different from
each other if the inner diameters are less than that of the entrance pipe section
of the liquid-side piping.
[0063] In addition, arrangement of the capillaries is not limited to the horizontal arrangement
and, for example, the capillaries may be made to stand upright inside the housing
if sufficient space can be secured inside the housing.
Reference Signs List
[0064] 1...multi-type air-conditioning system, 2...outdoor unit, 3...indoor unit, 4...refrigerant
piping, 5...compressor (hermetic type compressor), 7...outdoor heat exchanger, 12...expansion
valve (second expansion valve), 13...indoor heat exchanger, 61a, 61b...capillary
1. A multi-type air-conditioning system comprising:
an outdoor unit including an outdoor heat exchanger configured to cause heat exchange
to be carried out between a refrigerant compressed by a compressor and air;
a plurality of indoor units each including an expansion valve into which the refrigerant
passing through the outdoor heat exchanger flows and an indoor heat exchanger configured
to cause heat exchange to be carried out between the refrigerant decompressed by the
expansion valve and air, and each being exposed to the inside of a room to be air-conditioned;
and
refrigerant piping which connects the plurality of indoor units in parallel to the
outdoor unit, and through which the refrigerant circulating among the outdoor unit
and the indoor units flows, wherein
part of the refrigerant piping positioned inside each of the indoor units includes
a plurality of capillaries at a position on the upstream side of the expansion valve
in the flow direction of the refrigerant, and the capillaries are connected in parallel
to the refrigerant piping.
2. The multi-type air-conditioning system of Claim 1, wherein
each of the capillaries is a straight pipe possessing a predetermined total length
and configured to enhance the flow velocity of the refrigerant flowing therethrough
toward the expansion valve.
3. The multi-type air-conditioning system of Claim 1 or Claim 2, further comprising a
bifurcation pipe section connecting between an upstream end of each of the capillaries
and the refrigerant piping, and a confluence pipe section connecting between a downstream
end of each of the capillaries and the refrigerant piping.
4. The multi-type air-conditioning system of Claim 2, wherein
the indoor unit is a wall-mounted type unit which is exposed to the inside of a room
to be air-conditioned, and in which the plurality of capillaries are horizontally
arranged with a gap held between them.
5. The multi-type air-conditioning system of Claim 3, wherein
when a bore diameter of the expansion valve is d1, an inner diameter of the capillary
is d2, an inner diameter of the refrigerant piping connected to the bifurcation pipe
section is d3, and the number of the capillaries is n, the following relationship
is satisfied.
6. The multi-type air-conditioning system of Claim 1, wherein
at the time of a cooling operation and at the time of a defrosting operation, a flow
of the refrigerant passing through the outdoor heat exchanger is bifurcated into the
plurality of capillaries and the refrigerant passing through the plurality of capillaries
is guided to the expansion valve in a state where the bifurcated flows of the refrigerant
join together.
7. An indoor unit comprising:
an expansion valve;
refrigerant piping configured to guide a refrigerant which has been subjected to heat
exchange in an outdoor unit to the expansion valve; and
an indoor heat exchanger configured to carry out heat exchange with the refrigerant
decompressed by the expansion valve, wherein
a plurality of capillaries connected in parallel to the refrigerant piping are provided
at a position of the refrigerant piping on the upstream side of the expansion valve
in the flow direction of the refrigerant.
8. The indoor unit of Claim 7, wherein
each of the capillaries is a straight pipe possessing a predetermined total length
and configured to enhance the flow velocity of the refrigerant flowing therethrough
toward the expansion valve.
9. The indoor unit of Claim 7 or Claim 8, further comprising a bifurcation pipe section
connecting between an upstream end of each of the capillaries and the refrigerant
piping, and a confluence pipe section connecting between a downstream end of each
of the capillaries and the refrigerant piping.
10. The indoor unit of Claim 9, wherein
when a bore diameter of the expansion valve is d1, an inner diameter of the capillary
is d2, an inner diameter of the refrigerant piping connected to the bifurcation pipe
section is d3, and the number of the capillaries is n, the following relationship
is satisfied.