U.S. patent application number 17/743161 was filed with the patent office on 2022-08-25 for intermediate unit for refrigeration apparatus, and refrigeration apparatus.
This patent application is currently assigned to DAIKIN INDUSTRIES, LTD.. The applicant listed for this patent is DAIKIN INDUSTRIES, LTD.. Invention is credited to Takumi OHZONO, Shuichi TAGUCHI, Masaaki TAKEGAMI, Akitoshi UENO.
Application Number | 20220268498 17/743161 |
Document ID | / |
Family ID | |
Filed Date | 2022-08-25 |
United States Patent
Application |
20220268498 |
Kind Code |
A1 |
TAKEGAMI; Masaaki ; et
al. |
August 25, 2022 |
INTERMEDIATE UNIT FOR REFRIGERATION APPARATUS, AND REFRIGERATION
APPARATUS
Abstract
An intermediate unit includes a liquid-side pipe, a first valve,
and a refrigerant pressure sensor. The liquid-side pipe is
connected to a liquid connection pipe connecting a heat source unit
and a utilization unit together. A controller of the intermediate
unit adjusts the opening degree of the first valve based on a value
measured by the refrigerant pressure sensor. The pressure of a
refrigerant to be sent through the liquid connection pipe from the
intermediate unit to the utilization unit is adjusted by the first
valve.
Inventors: |
TAKEGAMI; Masaaki; (Osaka,
JP) ; UENO; Akitoshi; (Osaka, JP) ; TAGUCHI;
Shuichi; (Osaka, JP) ; OHZONO; Takumi; (Osaka,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DAIKIN INDUSTRIES, LTD. |
Osaka |
|
JP |
|
|
Assignee: |
DAIKIN INDUSTRIES, LTD.
Osaka
JP
|
Appl. No.: |
17/743161 |
Filed: |
May 12, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/JP2020/025138 |
Jun 26, 2020 |
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17743161 |
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International
Class: |
F25B 41/20 20060101
F25B041/20 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 18, 2019 |
JP |
2019-207898 |
Claims
1. An intermediate unit for a refrigeration apparatus, the
intermediate unit being provided between a heat source unit and a
utilization unit, the heat source unit and the utilization unit
being connected together through a liquid connection pipe and a gas
connection pipe to form the refrigeration apparatus, the
intermediate unit comprising: a liquid-side pipe connected to the
liquid connection pipe; a first valve provided for the liquid-side
pipe, the first valve having a variable opening degree; a
refrigerant pressure sensor disposed in a portion of the
liquid-side pipe closer to the utilization unit than the first
valve is, the refrigerant pressure sensor being configured to
measure a pressure of a refrigerant flowing through the liquid-side
pipe; and a controller configured to adjust the opening degree of
the first valve based on a value measured by the refrigerant
pressure sensor.
2. The intermediate unit of claim 1 further comprising: a gas-side
pipe connected to the gas connection pipe; a joint pipe connecting
the portion of the liquid-side pipe closer to the utilization unit
than the first valve is and the gas-side pipe together; and a
second valve provided for the joint pipe.
3. The intermediate unit of claim 2, wherein the controller adjusts
the opening degree of the first valve so that the value measured by
the refrigerant pressure sensor is less than or equal to a
reference pressure, and opens the second valve if the value
measured by the refrigerant pressure sensor is greater than the
reference pressure with the first valve closed.
4. The intermediate unit of claim 1, wherein the intermediate unit
is installed indoors, and is connected to the heat source unit
installed outdoors.
5. A refrigeration apparatus, comprising: the intermediate unit of
claim 1; a heat source unit; a utilization unit; and a liquid
connection pipe and a gas connection pipe connecting the
intermediate unit, the heat source unit, and the utilization unit
together to form a refrigerant circuit.
6. A refrigeration apparatus, comprising: the intermediate unit of
claim 2; a heat source unit; a plurality of utilization units; a
liquid connection pipe including a liquid-side trunk pipe and a
plurality of liquid-side branch pipes, the liquid-side trunk pipe
being connected to the heat source unit, the liquid-side branch
pipes each connecting an associated one of the utilization units to
the liquid-side trunk pipe; and a gas connection pipe including a
gas-side trunk pipe and a plurality of gas-side branch pipes, the
gas-side trunk pipe being connected to the heat source unit, the
gas-side branch pipes each connecting an associated one of the
utilization units to the gas-side trunk pipe, the liquid-side pipe
of the intermediate unit being connected to the liquid-side trunk
pipe of the liquid connection pipe, the gas-side pipe of the
intermediate unit being connected to the gas-side trunk pipe of the
gas connection pipe.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to an intermediate unit for a
refrigeration apparatus and a refrigeration apparatus.
BACKGROUND ART
[0002] Patent Document 1 discloses a heat source unit forming part
of a refrigeration apparatus. This heat source unit is connected
through a connection pipe to a show case or any other suitable
object, which is a utilization unit, and circulates a refrigerant
between the heat source unit and the utilization unit to perform a
refrigeration cycle.
CITATION LIST
Patent Document
[0003] Patent Document 1: Japanese Unexamined Patent Publication
No. 2017-138034
SUMMARY
[0004] A first aspect of the present disclosure is directed to an
intermediate unit (80) for a refrigeration apparatus (1). The
intermediate unit (80) is provided between a heat source unit (10)
and a utilization unit (60). The heat source unit (10) and the
utilization unit (60) are connected together through a liquid
connection pipe (4) and a gas connection pipe (5) to form the
refrigeration apparatus (1). The intermediate unit (80) includes: a
liquid-side pipe (81) connected to the liquid connection pipe (4);
a first valve (18) provided for the liquid-side pipe (81), the
first valve (18) having a variable opening degree; a refrigerant
pressure sensor (48) disposed in a portion of the liquid-side pipe
(81) closer to the utilization unit (60) than the first valve (18)
is, the refrigerant pressure sensor (48) being configured to
measure a pressure of a refrigerant flowing through the liquid-side
pipe (81); and a controller (85) configured to adjust the opening
degree of the first valve (18) based on a value measured by the
refrigerant pressure sensor (48).
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a piping system diagram illustrating a
configuration of a refrigeration apparatus according to an
embodiment.
[0006] FIG. 2 is a block diagram illustrating the relationship
among controllers, a sensor, and components of a refrigerant
circuit.
[0007] FIG. 3 corresponds to FIG. 1 and illustrates a flow of a
refrigerant through the refrigerant circuit during a cooling
operation.
[0008] FIG. 4 corresponds to FIG. 1 and illustrates a flow of the
refrigerant through the refrigerant circuit during a heating
operation.
[0009] FIG. 5 corresponds to FIG. 1 and illustrates the state of
the refrigerant circuit observed while refrigeration-facility units
are in a cooling-suspended state.
[0010] FIG. 6 is a flowchart showing how a hydraulic pressure
controller of an embodiment operates to control a first valve.
[0011] FIG. 7 is a graph showing the relationship between the
opening degree of a second valve controlled by the hydraulic
pressure controller of the embodiment and a value Pk measured by a
refrigerant pressure sensor.
[0012] FIG. 8 is a graph showing the relationship between the
opening degree of a second valve controlled by a hydraulic pressure
controller of a variation of the embodiment and a value Pk measured
by a refrigerant pressure sensor.
[0013] FIG. 9 is a block diagram illustrating the relationship
between components of an intermediate unit and a hydraulic pressure
controller.
DESCRIPTION OF EMBODIMENTS
[0014] Embodiments will be described below with reference to the
drawings. The embodiments below are merely exemplary ones in
nature, and are not intended to limit the scope, applications, or
use of the invention.
[0015] A refrigeration apparatus (1) of an embodiment can cool an
object to be cooled, and can condition indoor air. The object to be
cooled herein includes air in facilities such as a refrigerator, a
freezer, and a show case. Hereinafter, such facilities are each
referred to as a refrigeration-facility.
[0016] --General Configuration of Refrigeration Apparatus--
[0017] As illustrated in FIG. 1, the refrigeration apparatus (1)
includes a heat source unit (10) installed outdoors, a plurality of
air-conditioning units (50) configured to condition indoor air, a
plurality of refrigeration-facility units (60) configured to cool
air in a refrigeration-facility, an intermediate unit (80), and a
main controller (100). In the refrigeration apparatus (1) of the
present embodiment, the number of the heat source unit (10) is one,
the number of the refrigeration-facility units (60) is two or more,
and the number of the air-conditioning units (50) is two or more.
Note that the number of the refrigeration-facility units (60) or
the air-conditioning units (50) of the refrigeration apparatus (1)
may be one.
[0018] In the refrigeration apparatus (1), the heat source unit
(10), the refrigeration-facility units (60), the air-conditioning
units (50), the intermediate unit (80), and connection pipes (2, 3,
4, 5) connecting these units (10, 50, 60, 80) together form a
refrigerant circuit (6).
[0019] In the refrigerant circuit (6), a refrigerant circulates to
perform a refrigeration cycle. The refrigerant in the refrigerant
circuit (6) of the present embodiment is carbon dioxide. The
refrigerant circuit (6) is configured to perform the refrigeration
cycle so that the refrigerant has a pressure equal to or greater
than the critical pressure.
[0020] In the refrigerant circuit (6), the plurality of
air-conditioning units (50) are connected through a first liquid
connection pipe (2) and a first gas connection pipe (3) to the heat
source unit (10). In the refrigerant circuit (6), the plurality of
air-conditioning units (50) are connected together in parallel.
[0021] In the refrigerant circuit (6), the plurality of
refrigeration-facility units (60) are connected through a second
liquid connection pipe (4) and a second gas connection pipe (5) to
the heat source unit (10). In the refrigerant circuit (6), the
plurality of refrigeration-facility units (60) are connected
together in parallel.
[0022] In the refrigerant circuit (6), the intermediate unit (80)
is connected to the second liquid connection pipe (4) and the
second gas connection pipe (5) that connect the heat source unit
(10) and the refrigeration-facility units (60) together. In other
words, the intermediate unit (80) is disposed between the heat
source unit (10) and the refrigeration-facility units (60) in the
refrigerant circuit (6).
[0023] The second liquid connection pipe (4) includes one first
liquid-side trunk pipe (4a), one second liquid-side trunk pipe
(4b), and liquid-side branch pipes (4c) equal in number to the
refrigeration-facility units (60). The first liquid-side trunk pipe
(4a) is provided for a portion of the intermediate unit (80) near
the heat source unit (10). The second liquid-side trunk pipe (4b)
is provided for a portion of the intermediate unit (80) near the
refrigeration-facility units (60).
[0024] Specifically, the first liquid-side trunk pipe (4a) connects
the heat source unit (10) and the intermediate unit (80) together.
One end of the second liquid-side trunk pipe (4b) is connected to
the intermediate unit (80). The other end of the second liquid-side
trunk pipe (4b) is connected to one end of each liquid-side branch
pipe (4c). The other end of each liquid-side branch pipe (4c) is
connected to an associated one of the refrigeration-facility units
(60).
[0025] The second gas connection pipe (5) includes one first
gas-side trunk pipe (5a), one second gas-side trunk pipe (5b), and
gas-side branch pipes (5c) equal in number to the
refrigeration-facility units (60). The first gas-side trunk pipe
(5a) is provided for the portion of the intermediate unit (80) near
the heat source unit (10). The second gas-side trunk pipe (5b) is
provided for the portion of the intermediate unit (80) near the
refrigeration-facility units (60).
[0026] Specifically, the first gas-side trunk pipe (5a) connects
the heat source unit (10) and the intermediate unit (80) together.
One end of the second gas-side trunk pipe (5b) is connected to the
intermediate unit (80). The other end of the second gas-side branch
pipe (5b) is connected to one end of each gas-side branch pipe
(5c). The other end of each gas-side branch pipe (5c) is connected
to an associated one of the refrigeration-facility units (60).
[0027] --Heat Source Unit--
[0028] The heat source unit (10) includes an outdoor fan (12) and
an outdoor circuit (11). The outdoor circuit (11) includes a
compression element (C), a flow path switching mechanism (30), an
outdoor heat exchanger (13), an outdoor expansion valve (14), a
gas-liquid separator (15), a subcooling heat exchanger (16), and an
intercooler (17). The heat source unit (10) further includes an
outdoor controller (101).
[0029] <Compression Element>
[0030] The compression element (C) compresses the refrigerant. The
compression element (C) includes a first compressor (21), a second
compressor (22), and a third compressor (23). The first, second,
and third compressors (21), (22), and (23) are each a rotary
compressor in which a motor drives a compression mechanism. The
first, second, and third compressors (21), (22), and (23) are each
configured as a variable capacity compressor capable of changing
the rotational speed of the compression mechanism.
[0031] The compression element (C) performs two-stage compression.
The first compressor (21) that is a high-stage compressor
constitutes a first compression section. The second and third
compressors (22) and (23) that are low-stage compressors constitute
a second compression section.
[0032] A first suction pipe (21a) and a first discharge pipe (21b)
are connected to the first compressor (21). A second suction pipe
(22a) and a second discharge pipe (22b) are connected to the second
compressor (22). A third suction pipe (23a) and a third discharge
pipe (23b) are connected to the third compressor (23). In the
compression element (C), the second and third discharge pipes (22b)
and (23b) are connected to the first suction pipe (21a).
[0033] The second suction pipe (22a) is connected through a pipe to
the first gas-side trunk pipe (5a) of the second gas connection
pipe (5). The second compressor (22) communicates with the
refrigeration-facility units (60) through the second gas connection
pipe (5). The second compressor (22) is a refrigeration-facility
compressor associated with the refrigeration-facility units (60).
The third suction pipe (23a) communicates with the air-conditioning
units (50). The third compressor (23) is an indoor-side compressor
associated with the air-conditioning units (50).
[0034] The compression element (C) includes a second bypass pipe
(24b) and a third bypass pipe (24c). The second bypass pipe (24b)
is a pipe through which the refrigerant is passed while bypassing
the second compressor (22). The second bypass pipe (24b) has two
ends respectively connected to the second suction pipe (22a) and
the second discharge pipe (22b). The third bypass pipe (24c) is a
pipe through which the refrigerant is passed while bypassing the
third compressor (23). The third bypass pipe (24c) has two ends
respectively connected to the third suction pipe (23a) and the
third discharge pipe (23b).
[0035] <Flow Path Switching Mechanism>
[0036] The flow path switching mechanism (30) selects one of paths
through which the refrigerant flows in the refrigerant circuit (6).
The flow path switching mechanism (30) includes a first pipe (31),
a second pipe (32), a third pipe (33), a fourth pipe (34), a first
three-way valve (TV1), and a second three-way valve (TV2). The
inflow end of the first pipe (31) and the inflow end of the second
pipe (32) are connected to the first discharge pipe (21b). The
first pipe (31) and the second pipe (32) are pipes on which the
discharge pressure of the compression element (C) acts. The outflow
end of the third pipe (33) and the outflow end of the fourth pipe
(34) are connected to the third suction pipe (23a) of the third
compressor (23). The third pipe (33) and the fourth pipe (34) are
pipes on which the suction pressure of the compression element (C)
acts.
[0037] The first three-way valve (TV1) has a first port (P1), a
second port (P2), and a third port (P3). The first port (P1) of the
first three-way valve (TV1) is connected to the outflow end of the
first pipe (31) that is a high-pressure flow path. The second port
(P2) of the first three-way valve (TV1) is connected to the inflow
end of the third pipe (33) that is a low-pressure flow path. The
third port (P3) of the first three-way valve (TV1) is connected to
one end of an indoor gas-side flow path (35). The other end of the
indoor gas-side flow path (35) is connected to the first gas
connection pipe (3).
[0038] The second three-way valve (TV2) has a first port (P1), a
second port (P2), and a third port (P3). The first port (P1) of the
second three-way valve (TV2) is connected to the outflow end of the
second pipe (32) that is a high-pressure flow path. The second port
(P2) of the second three-way valve (TV2) is connected to the inflow
end of the fourth pipe (34) that is a low-pressure flow path. The
third port (P3) of the second three-way valve (TV2) is connected to
an outdoor gas-side flow path (36).
[0039] The first three-way valve (TV1) and the second three-way
valve (TV2) are each an electric three-way valve. The three-way
valves (TV1, TV2) are each switched between the first state (the
state indicated by a solid line in FIG. 1) and the second state
(the state indicated by a dashed line in FIG. 1). In the three-way
valves (TV1, TV2) in the first state, the first port (P1) and the
third port (P3) communicate with each other, and the second port
(P2) is closed. In the three-way valves (TV1, TV2) in the second
state, the second port (P2) and the third port (P3) communicate
with each other, and the first port (P1) is closed.
[0040] <Outdoor Heat Exchanger>
[0041] The outdoor heat exchanger (13) constitutes a
heat-source-side heat exchanger. The outdoor heat exchanger (13) is
a fin-and-tube air heat exchanger. The outdoor fan (12) is disposed
near the outdoor heat exchanger (13). The outdoor fan (12)
transfers outdoor air. The outdoor heat exchanger exchanges heat
between a refrigerant flowing therethrough and outdoor air
transferred from the outdoor fan (12).
[0042] The gas end of the outdoor heat exchanger (13) is connected
to the outdoor gas-side flow path (36). The liquid end of the
outdoor heat exchanger (13) is connected to an outdoor flow path
(O).
[0043] <Outdoor Flow Path>
[0044] The outdoor flow path (O) includes a first outdoor pipe
(o1), a second outdoor pipe (o2), a third outdoor pipe (o3), a
fourth outdoor pipe (o4), a fifth outdoor pipe (o5), a sixth
outdoor pipe (o6), a seventh outdoor pipe (o7), and an eighth
outdoor pipe (o8).
[0045] One end of the first outdoor pipe (o1) is connected to the
liquid end of the outdoor heat exchanger (13). The other end of the
first outdoor pipe (o1) is connected to one end of the second
outdoor pipe (o2) and one end of the third outdoor pipe (o3). The
other end of the second outdoor pipe (o2) is connected to the top
of the gas-liquid separator (15).
[0046] One end of the fourth outdoor pipe (o4) is connected to the
bottom of the gas-liquid separator (15). The other end of the
fourth outdoor pipe (o4) is connected to one end of the fifth
outdoor pipe (o5) and the other end of the third outdoor pipe (o3).
The other end of the fifth outdoor pipe (o5) is connected to one
end of the sixth outdoor pipe (o6) and one end of the eighth
outdoor pipe (o8).
[0047] The other end of the eighth outdoor pipe (o8) is connected
to the first liquid-side trunk pipe (4a) of the second liquid
connection pipe (4). The eighth outdoor pipe (o8) is a liquid pipe
through which a liquid refrigerant downstream of the gas-liquid
separator (15) flows. The other end of the sixth outdoor pipe (o6)
is connected to the first liquid connection pipe (2). One end of
the seventh outdoor pipe (o7) is connected to an intermediate
portion of the sixth outdoor pipe (o6). The other end of the
seventh outdoor pipe (o7) is connected to an intermediate portion
of the second outdoor pipe (o2).
[0048] <Outdoor Expansion Valve>
[0049] The first outdoor pipe (o1) of the outdoor circuit (11) is
provided with an outdoor expansion valve (14). The outdoor
expansion valve (14) is an electronic expansion valve that has its
opening degree adjusted by a pulse motor driven in response to a
pulse signal from the main controller (100).
[0050] <Gas-Liquid Separator>
[0051] The gas-liquid separator (15) constitutes a container that
stores the refrigerant. The gas-liquid separator (15) is provided
downstream of the outdoor expansion valve (14). In the gas-liquid
separator (15), the refrigerant is separated into a gas refrigerant
and a liquid refrigerant. The top of the gas-liquid separator (15)
is connected to the other end of the second outdoor pipe (o2) and
one end of a venting pipe (37), which will be described below.
[0052] <Intermediate Injection Circuit>
[0053] The outdoor circuit (11) includes an intermediate injection
circuit (49). The intermediate injection circuit (49) is a circuit
through which the refrigerant decompressed by a decompression valve
(40) is supplied to an intermediate pressure section of the
compression element (C) between the first compression section (21)
and the second compression section (22, 23). The intermediate
injection circuit (49) includes the venting pipe (37) and an
injection pipe (38).
[0054] One end of the injection pipe (38) is connected to an
intermediate portion of the fifth outdoor pipe (o5). The other end
of the injection pipe (38) is connected to the first suction pipe
(21a) of the first compressor (21). The injection pipe (38) is
provided with the decompression valve (40). The decompression valve
(40) is an expansion valve having a variable opening degree.
[0055] The venting pipe (37) is configured to allow the gas
refrigerant in the gas-liquid separator (15) to flow out of the
gas-liquid separator (15) into a flow path between the first
compression section (21) and the second compression section (22,
23). Specifically, one end of the venting pipe (37) is connected to
the top of the gas-liquid separator (15). The other end of the
venting pipe (37) is connected to an intermediate portion of the
injection pipe (38). The venting pipe (37) is connected to a
venting valve (39). The venting valve (39) is an electronic
expansion valve having a variable opening degree.
[0056] <Subcooling Heat Exchanger>
[0057] The outdoor circuit (11) includes the subcooling heat
exchanger (16). The subcooling heat exchanger (16) is a cooling
heat exchanger configured to cool the refrigerant (mainly the
liquid refrigerant) separated in the gas-liquid separator (15). The
subcooling heat exchanger (16) is connected between the gas-liquid
separator (15) and a first valve (18). The subcooling heat
exchanger (16) has a first flow path (16a) serving as a
high-pressure flow path and a second flow path (16b) serving as a
low-pressure flow path. In the subcooling heat exchanger (16), heat
exchange occurs between the high-pressure refrigerant flowing
through the first flow path (16a) and the decompressed refrigerant
flowing through the second flow path (16b).
[0058] The refrigerant flowing through the first flow path (16a) is
cooled in the subcooling heat exchanger (16). The first flow path
(16a) is connected to an intermediate portion of the fourth outdoor
pipe (o4) serving as a liquid pipe through which the liquid
refrigerant in the outdoor circuit (11) flows.
[0059] The second flow path (16b) is a flow path through which the
refrigerant serving to cool the refrigerant flowing through the
first flow path (16a) flows. The second flow path (16b) is included
in the intermediate injection circuit (49). Specifically, the
second flow path (16b) is connected to a portion of the injection
pipe (38) downstream of the decompression valve (40). The
refrigerant that has been decompressed at the decompression valve
(40) flows through the second flow path (16b).
[0060] <Intercooler>
[0061] The intercooler (17) is connected to an intermediate flow
path (41). One end of the intermediate flow path (41) is connected
to the second discharge pipe (22b) of the second compressor (22)
and the third discharge pipe (23b) of the third compressor (23).
The other end of the intermediate flow path (41) is connected to
the first suction pipe (21a) of the first compressor (21). In other
words, the other end of the intermediate flow path (41) is
connected to the intermediate pressure section of the compression
element (C).
[0062] The intercooler (17) is a fin-and-tube air heat exchanger. A
cooling fan (17a) is disposed near the intercooler (17). The
intercooler (17) exchanges heat between the refrigerant flowing
therethrough and the outdoor air transferred from the cooling fan
(17a).
[0063] <Oil Separation Circuit>
[0064] The outdoor circuit (11) includes an oil separation circuit
(42). The oil separation circuit (42) includes an oil separator
(43), a first oil return pipe (44), a second oil return pipe (45),
and a third oil return pipe (46).
[0065] The oil separator (43) is connected to the first discharge
pipe (21b) of the first compressor (21). The oil separator (43)
separates oil from the refrigerant discharged from the compression
element (C).
[0066] The inflow end of the first oil return pipe (44)
communicates with the oil separator (43). The outflow end of the
first oil return pipe (44) is connected to the second suction pipe
(22a) of the second compressor (22). The inflow end of the second
oil return pipe (45) communicates with the oil separator (43). The
outflow end of the second oil return pipe (45) is connected to the
inflow end of the intermediate flow path (41).
[0067] The third oil return pipe (46) includes a main return pipe
(46a), a refrigeration-facility-side branch pipe (46b), and an
indoor-side branch pipe (46c). The inflow end of the main return
pipe (46a) communicates with the oil separator (43). The outflow
end of the main return pipe (46a) is connected to the inflow end of
the refrigeration-facility-side branch pipe (46b) and the inflow
end of the indoor-side branch pipe (46c). The outflow end of the
refrigeration-facility-side branch pipe (46b) communicates with an
oil reservoir inside a casing of the second compressor (22). The
outflow end of the indoor-side branch pipe (46c) communicates with
an oil reservoir inside a casing of the third compressor (23).
[0068] The first oil return pipe (44) is connected to a first oil
level control valve (47a). The second oil return pipe (45) is
connected to a second oil level control valve (47b). The
refrigeration-facility-side branch pipe (46b) is connected to a
third oil level control valve (47c). The indoor-side branch pipe
(46c) is connected to a fourth oil level control valve (47d).
[0069] A portion of oil separated in the oil separator (43) returns
to the second compressor (22) via the first oil return pipe (44).
Another portion of the oil separated in the oil separator (43)
returns to the third compressor (23) via the second oil return pipe
(45). The remaining portion of the oil separated in the oil
separator (43) returns to the oil reservoir in the casing of each
of the second compressor (22) and the third compressor (23) via the
third oil return pipe (46).
[0070] <Check Valve>
[0071] The outdoor circuit (11) has a first check valve (CV1), a
second check valve (CV2), a third check valve (CV3), a fourth check
valve (CV4), a fifth check valve (CV5), a sixth check valve (CV6),
a seventh check valve (CV7), an eighth check valve (CV8), and a
ninth check valve (CV9). Each of these check valves (CV1 to CV9)
allows the refrigerant to flow in the direction of the associated
arrow shown in FIG. 1 and prohibits the refrigerant to flow in the
opposite direction.
[0072] The first check valve (CV1) is connected to the first
discharge pipe (21b). The second check valve (CV2) is connected to
the second discharge pipe (22b). The third check valve (CV3) is
connected to the third discharge pipe (23b). The fourth check valve
(CV4) is connected to the second outdoor pipe (o2). The fifth check
valve (CV5) is connected to the third outdoor pipe (o3). The sixth
check valve (CV6) is connected to the sixth outdoor pipe (o6). The
seventh check valve (CV7) is connected to the seventh outdoor pipe
(o7). The eighth check valve (CV8) is connected to the second
bypass pipe (24b). The ninth check valve (CV9) is connected to the
third bypass pipe (24c).
[0073] <Sensor>
[0074] The heat source unit (10) includes various sensors. The
sensors include a high-pressure sensor (71), an
intermediate-pressure sensor (72), a first low-pressure sensor
(73), a second low-pressure sensor (74), and a liquid refrigerant
pressure sensor (75).
[0075] The high-pressure sensor (71) detects the pressure of the
refrigerant (the pressure (HP) of a high-pressure refrigerant)
discharged from the first compressor (21). The
intermediate-pressure sensor (72) detects the pressure of the
refrigerant in the intermediate flow path (41), i.e., the pressure
of the refrigerant between the first compressor (21) and a pair of
the second and third compressors (22) and (23) (the pressure (MP)
of an intermediate-pressure refrigerant). The first low-pressure
sensor (73) detects the pressure of the refrigerant (the pressure
(LP1) of a first low-pressure refrigerant) to be sucked by the
second compressor (22). The second low-pressure sensor (74) detects
the pressure of the refrigerant (the pressure (LP2) of a second
low-pressure refrigerant) to be sucked by the third compressor
(23). The liquid refrigerant pressure sensor (75) detects the
pressure of the liquid refrigerant (the pressure (RP) of the liquid
refrigerant) in the gas-liquid separator (15).
[0076] --Air-Conditioning Unit--
[0077] The air-conditioning units (50) are utilization units
installed indoors. The air-conditioning units (50) each condition
air in an indoor space. The air-conditioning units (50) each
include an indoor fan (52) and an indoor circuit (51). The liquid
end of the indoor circuit (51) is connected to the first liquid
connection pipe (2). The gas end of the indoor circuit (51) is
connected to the first gas connection pipe (3).
[0078] The indoor circuit (51) includes an indoor expansion valve
(53) and an indoor heat exchanger (54) in order from the liquid end
to the gas end. The indoor expansion valve (53) is a first
utilization expansion valve. The indoor expansion valve (53) is an
electronic expansion valve having a variable opening degree.
[0079] The indoor heat exchanger (54) is a fin-and-tube air heat
exchanger. The indoor fan (52) is disposed near the indoor heat
exchanger (54). The indoor fan (52) transfers indoor air. The
indoor heat exchanger (54) exchanges heat between a refrigerant
flowing therethrough and indoor air transferred from the indoor fan
(52).
[0080] The air-conditioning units (50) each include an indoor
controller (102). Although not shown, the air-conditioning units
(50) each include a plurality of temperature sensors. The
temperature sensors of each air-conditioning unit (50) include a
sensor configured to measure the temperature of indoor air and a
sensor configured to measure the temperature of the refrigerant
flowing through the indoor circuit (51).
[0081] --Main Controller--
[0082] As illustrated in FIG. 2, the main controller (100) includes
an outdoor controller (101) for the heat source unit (10) and the
indoor controllers (102) for the respective air-conditioning units
(50). The outdoor controller (101) and each of the indoor
controllers (102) forming the main controller (100) are connected
together through a communication line to be capable of
communicating with each other.
[0083] The outdoor controller (101) and the indoor controllers
(102) each include a microcomputer mounted on a control board, and
a memory device (specifically, a semiconductor memory) storing
software for operating the microcomputer. The main controller (100)
controls various components of the refrigeration apparatus (1)
based on detection signals of the various sensors.
[0084] The outdoor controller (101) controls the compression
element (C) so that a value measured by the high-pressure sensor
(71) (the pressure (HP) of the high-pressure refrigerant) is
greater than or equal to the critical pressure of the refrigerant
(in the present embodiment, carbon dioxide). The outdoor controller
(101) controls the outdoor expansion valve (14) so that the
refrigerant pressure in the gas-liquid separator (15)
(specifically, a value measured by the liquid refrigerant pressure
sensor (75)) is less than the critical pressure of the
refrigerant.
[0085] The outdoor controller (101) controls the cooling capability
of the subcooling heat exchanger (16). Specifically, the outdoor
controller (101) controls the decompression valve (40) so that the
refrigerant flowing out of the subcooling heat exchanger (16) is
subcooled.
[0086] The indoor controllers (102) each control the operation of
the associated air-conditioning unit (50) so that the temperature
of air sucked into the associated air-conditioning unit (50)
becomes equal to a set temperature. Specifically, the indoor
controllers (102) each control the associated indoor expansion
valve (53) and the associated indoor fan (52).
[0087] --Refrigeration-Facility Unit--
[0088] The refrigeration-facility units (60) are each, for example,
a refrigerated show case installed in a store, such as a
convenience store. Each refrigeration-facility unit (60) is a
utilization unit that is installed indoors to cool air in the show
case (inside air). The refrigeration-facility unit (60) includes a
refrigeration-facility fan (62) and a refrigeration-facility
circuit (61). The liquid end of the refrigeration-facility circuit
(61) is connected to the associated liquid-side branch pipe (4c) of
the second liquid connection pipe (4). The gas end of the
refrigeration-facility circuit (61) is connected to the associated
gas-side branch pipe (5c) of the second gas connection pipe
(5).
[0089] The refrigeration-facility circuit (61) includes a
refrigeration-facility expansion valve (63) and a
refrigeration-facility heat exchanger (64) in order from the liquid
end to the gas end. The refrigeration-facility expansion valve (63)
is configured as an electronic expansion valve having a variable
opening degree.
[0090] The refrigeration-facility heat exchanger (64) is a
fin-and-tube air heat exchanger. The refrigeration-facility fan
(62) is disposed near the refrigeration-facility heat exchanger
(64). The refrigeration-facility fan (62) transfers inside air. The
refrigeration-facility heat exchanger (64) exchanges heat between
the refrigerant flowing therethrough and inside air transferred
from the refrigeration-facility fan (62).
[0091] The refrigeration-facility units (60) each include a
refrigeration-facility controller (103). Although not shown, the
refrigeration-facility units (60) each include a plurality of
temperature sensors. The temperature sensors of each
refrigeration-facility unit (60) include a sensor configured to
measure the temperature of inside air and a sensor configured to
measure the temperature of the refrigerant flowing through the
refrigeration-facility circuit (61).
[0092] As illustrated in FIG. 2, the refrigeration-facility
controllers (103) each include a microcomputer mounted on a control
board, and a memory device (specifically, a semiconductor memory)
storing software for operating the microcomputer. The
refrigeration-facility controllers (103) do not communicate with
the outdoor controller (101) and the indoor controllers (102).
[0093] Each refrigeration-facility controller (103) controls the
associated refrigeration-facility expansion valve (63) and the
associated refrigeration-facility fan (62) based on detection
signals of the various sensors. The refrigeration-facility
controller (103) adjusts the opening degree of the associated
refrigeration-facility expansion valve (63) so that the degree of
superheat of the refrigerant at the outlet of the associated
refrigeration-facility heat exchanger (64) functioning as an
evaporator becomes equal to a predetermined target value. If the
temperature of inside air falls within a set temperature range, the
refrigeration-facility controller (103) allows a cooling operation
of the associated refrigeration-facility unit (60) to be suspended.
In this cooling-suspended state, while the refrigeration-facility
fan (62) operates, the refrigeration-facility expansion valve (63)
is closed.
[0094] --Intermediate Unit--
[0095] The intermediate unit (80) is separate from the heat source
unit (10), the air-conditioning units (50), and the
refrigeration-facility units (60). The intermediate unit (80)
includes a liquid-side pipe (81), a gas-side pipe (82), and a joint
pipe (83). Although not shown, the intermediate unit (80) includes
a casing that houses the liquid-side pipe (81), the gas-side pipe
(82), and the joint pipe (83). The intermediate unit (80) is
installed indoors together with the refrigeration-facility units
(60).
[0096] One end of the liquid-side pipe (81) is connected to the
first liquid-side trunk pipe (4a) of the second liquid connection
pipe (4), and the other end thereof is connected to the second
liquid-side trunk pipe (4b) of the second liquid connection pipe
(4). As can be seen, the liquid-side pipe (81) is connected to the
liquid-side trunk pipes (4a, 4b) of the second liquid connection
pipe (4) connecting the heat source unit (10) and the
refrigeration-facility units (60) together.
[0097] The liquid-side pipe (81) is provided with the first valve
(18) and a refrigerant pressure sensor (48) in order from the one
end to the other end thereof. Thus, the refrigerant pressure sensor
(48) is disposed in a portion of the liquid-side pipe (81) closer
to the refrigeration-facility units (60) than the first valve (18)
is.
[0098] The first valve (18) is a control valve having a variable
opening degree. The first valve (18) of the present embodiment is
an electronic expansion valve including a pulse motor that drives
its valve body. The refrigerant pressure sensor (48) measures the
pressure of the refrigerant flowing through the liquid-side pipe
(81). A value measured by the refrigerant pressure sensor (48) is
substantially equal to the pressure of the refrigerant flowing
through the liquid-side pipe (81) into the second liquid-side trunk
pipe (4b).
[0099] One end of the gas-side pipe (82) is connected to the first
gas-side trunk pipe (5a) of the second gas connection pipe (5), and
the other end thereof is connected to the second gas-side trunk
pipe (5b) of the second gas connection pipe (5). As can be seen,
the gas-side pipe (82) is connected to the gas-side trunk pipes
(5a, 5b) of the second gas connection pipe (5) connecting the heat
source unit (10) and the refrigeration-facility units (60)
together.
[0100] One end of the joint pipe (83) is connected to the
liquid-side pipe (81), and the other end thereof is connected to
the gas-side pipe (82). The one end of the join pipe (83) is
connected to a portion of the liquid-side pipe (81) closer to the
second liquid-side trunk pipe (4b) than the first valve (18) is.
The one end of the join pipe (83) of the present embodiment is
connected to a portion of the liquid-side pipe (81) closer to the
second liquid-side trunk pipe (4b) than the refrigerant pressure
sensor (48) is. Note that the one end of the joint pipe (83) may be
connected to a portion of the liquid-side pipe (81) between the
first valve (18) and the refrigerant pressure sensor (48).
[0101] The joint pipe (83) is provided with a second valve (19).
The second valve (19) is a control valve having a variable opening
degree. The second valve (19) of the present embodiment is an
electronic expansion valve including a pulse motor that drives its
valve body.
[0102] The intermediate unit (80) includes a hydraulic pressure
controller (85). The hydraulic pressure controller (85) is
connected to the first valve (18), the second valve (19), and the
refrigerant pressure sensor (48) via communication lines. The
hydraulic pressure controller (85) controls the first and second
valves (18) and (19) based on the value measured by the refrigerant
pressure sensor (48).
[0103] As illustrated in FIG. 2, the hydraulic pressure controller
(85) includes a microcomputer mounted on a control board, and a
memory device (specifically, a semiconductor memory) storing
software for operating the microcomputer. The hydraulic pressure
controller (85) does not communicate with the outdoor controller
(101), the indoor controllers (102), and the refrigeration-facility
controllers (103).
[0104] --Operation of Refrigeration Apparatus--
[0105] An operation of the refrigeration apparatus (1) will be
described. The refrigeration apparatus (1) can perform a cooling
operation and a heating operation. The cooling operation is an
operation in which the air-conditioning units (50) cool the
respective indoor spaces. The heating operation is an operation in
which the air-conditioning units (50) heat the respective indoor
spaces. In each of the cooling operation and the heating operation,
the refrigeration-facility units (60) are each either in an active
state or in the cooling-suspended state.
[0106] <Cooling Operation>
[0107] The cooling operation of the refrigeration apparatus (1)
will be described with reference to FIG. 3. The cooling operation
will be hereinafter described using an example in which the
refrigeration-facility units (60) are in the active state.
[0108] In the cooling operation illustrated in FIG. 3, the
refrigerant circuit (6) allows the refrigerant to circulate
therethrough to perform a refrigeration cycle. The outdoor heat
exchanger (13) functions as a radiator (a gas cooler), and the
refrigeration-facility heat exchangers (64) and the indoor heat
exchangers (54) function as evaporators.
[0109] In the cooling operation illustrated in FIG. 3, the first
three-way valve (TV1) is set in the second state, and the second
three-way valve (TV2) is set in the first state. The outdoor
expansion valve (14), the refrigeration-facility expansion valves
(63), the indoor expansion valves (53), the decompression valve
(40), and the first valve (18) have their opening degrees adjusted
as appropriate. The outdoor fan (12), the cooling fan (17a), the
refrigeration-facility fans (62), and the indoor fans (52) operate.
The first, second, and third compressors (21), (22), and (23)
operate.
[0110] The refrigerant that has been compressed in each of the
second and third compressors (22) and (23) dissipates heat to
outdoor air in the intercooler (17), and is then sucked into the
first compressor (21). The refrigerant that has been compressed in
the first compressor (21) dissipates heat to outdoor air in the
outdoor heat exchanger (13), and is then decompressed while passing
through the outdoor expansion valve (14). The decompressed
refrigerant has a pressure that is lower than a second pressure
(critical pressure). This refrigerant passes through the gas-liquid
separator (15), and is then cooled in the subcooling heat exchanger
(16). A portion of the refrigerant that has been cooled in the
subcooling heat exchanger (16) flows into the eighth outdoor pipe
(o8), and the remaining portion thereof flows into the sixth
outdoor pipe (o6).
[0111] The refrigerant that has flowed into the sixth outdoor pipe
(o6) flows through the first liquid connection pipe (2), and is
distributed among the plurality of air-conditioning units (50). In
each air-conditioning unit (50), the refrigerant that has flowed
into the indoor circuit (51) is decompressed while passing through
the indoor expansion valve (53), and then absorbs heat from the
indoor air to evaporate in the indoor heat exchanger (54). The
air-conditioning unit (50) blows the air cooled in the indoor heat
exchanger (54) into the indoor space. The flows of the refrigerant
that has flowed out of the indoor heat exchangers (54) of the
air-conditioning units (50) enter the first gas connection pipe (3)
to merge together. Thereafter, this refrigerant flows into the
outdoor circuit (11), and is then sucked into the third compressor
(23) so as to be again compressed.
[0112] The refrigerant that has flowed into the eighth outdoor pipe
(o8) flows through the first liquid-side trunk pipe (4a) of the
second liquid connection pipe (4) into the liquid-side pipe (81) of
the intermediate unit (80). The refrigerant that has flowed into
the liquid-side pipe (81) is decompressed while passing through the
first valve (18), then passes through the second liquid-side trunk
pipe (4b) and the liquid-side branch pipes (4c) of the second
liquid connection pipe (4), and is distributed among the plurality
of refrigeration-facility units (60).
[0113] In each refrigeration-facility unit (60), the refrigerant
that has flowed into the refrigeration-facility circuit (61) is
decompressed while passing through the refrigeration-facility
expansion valve (63), and then absorbs heat from the inside air to
evaporate in the refrigeration-facility heat exchanger (64). The
refrigeration-facility unit (60) blows the air cooled in the
refrigeration-facility heat exchanger (64) into a space inside the
refrigeration-facility.
[0114] The flows of the refrigerant that has flowed out of the
refrigeration-facility heat exchangers (64) of the
refrigeration-facility units (60) enter the second gas connection
pipe (5) to merge together. Thereafter, this refrigerant flows into
the gas-side pipe (82) of the intermediate unit (80), passes
through the gas-side pipe (82), and then flows through the first
gas-side trunk pipe (5a) into the outdoor circuit (11). Thereafter,
the refrigerant is sucked into the second compressor (22) so as to
be again compressed.
[0115] <Heating Operation>
[0116] The heating operation of the refrigeration apparatus (1)
will be described with reference to FIG. 4. The heating operation
will be hereinafter described using an example in which the
refrigeration-facility units (60) are in the active state.
[0117] In the heating operation illustrated in FIG. 4, the
refrigerant circuit (6) allows the refrigerant to circulate
therethrough to perform a refrigeration cycle. The indoor heat
exchangers (54) function as radiators (gas coolers), and the
refrigeration-facility heat exchangers (64) and the outdoor heat
exchanger (13) function as evaporators. Note that, in the heating
operation, the refrigeration apparatus (1) of the present
embodiment is operable either in a mode in which the outdoor heat
exchanger (13) functions as a radiator or in a mode in which the
outdoor heat exchanger (13) is suspended.
[0118] In the heating operation illustrated in FIG. 4, the first
three-way valve (TV1) is set in the first state, and the second
three-way valve (TV2) is set in the second state. The outdoor
expansion valve (14), the refrigeration-facility expansion valves
(63), the indoor expansion valves (53), the decompression valve
(40), and the first valve (18) have their opening degrees adjusted
as appropriate. The outdoor fan (12), the refrigeration-facility
fans (62), and the indoor fans (52) operate, and the cooling fan
(17a) is suspended. The first, second, and third compressors (21),
(22), and (23) operate.
[0119] The refrigerant that has been compressed in each of the
second and third compressors (22) and (23) passes through the
intercooler (17), and is then sucked into the first compressor
(21). The refrigerant that has been compressed in the first
compressor (21) flows through the first gas connection pipe (3),
and is distributed among the plurality of air-conditioning units
(50). In each air-conditioning unit (50), the refrigerant that has
flowed into the indoor circuit (51) dissipates heat to the indoor
air in the indoor heat exchanger (54), and then flows into the
first liquid connection pipe (2) after passing through the indoor
expansion valve (53). The air-conditioning unit (50) blows the air
heated in the indoor heat exchanger (54) into the indoor space.
[0120] The flows of the refrigerant that has flowed out of the
air-conditioning units (50) into the first liquid connection pipe
(2) merge together. Thereafter, this refrigerant flows through the
seventh outdoor pipe (o7) of the outdoor circuit (11) into the
gas-liquid separator (15), and is then cooled in the subcooling
heat exchanger (16). A portion of the refrigerant that has been
cooled in the subcooling heat exchanger (16) flows into the fifth
outdoor pipe (o5), and the remaining portion thereof flows into the
third outdoor pipe (o3).
[0121] The refrigerant that has flowed into the fifth outdoor pipe
(o5) then flows through the eighth outdoor pipe (o8) and the first
liquid-side trunk pipe (4a) of the second liquid connection pipe
(4) in this order into the liquid-side pipe (81) of the
intermediate unit (80). The refrigerant that has flowed into the
liquid-side pipe (81) is decompressed while passing through the
first valve (18), then passes through the second liquid-side trunk
pipe (4b) and the liquid-side branch pipes (4c) of the second
liquid connection pipe (4), and is distributed among the plurality
of refrigeration-facility units (60).
[0122] In each refrigeration-facility unit (60), the refrigerant
that has flowed into the refrigeration-facility circuit (61) is
decompressed while passing through the refrigeration-facility
expansion valve (63), and then absorbs heat from the inside air to
evaporate in the refrigeration-facility heat exchanger (64). The
refrigeration-facility unit (60) blows the air cooled in the
refrigeration-facility heat exchanger (64) into a space inside the
refrigeration-facility.
[0123] The flows of the refrigerant that has flowed out of the
refrigeration-facility heat exchangers (64) of the
refrigeration-facility units (60) enter the second gas connection
pipe (5) to merge together. Thereafter, this refrigerant flows into
the gas-side pipe (82) of the intermediate unit (80), passes
through the gas-side pipe (82), and then flows through the first
gas-side trunk pipe (5a) into the outdoor circuit (11). Thereafter,
the refrigerant is sucked into the second compressor (22) so as to
be again compressed.
[0124] The refrigerant that has flowed into the third outdoor pipe
(o3) is decompressed while passing through the outdoor expansion
valve (14), then flows into the outdoor heat exchanger (13), and
absorbs heat from the outdoor air to evaporate in the outdoor heat
exchanger (13). The refrigerant that has flowed out of the outdoor
heat exchanger (13) is sucked into the third compressor (23) so as
to be again compressed.
[0125] <Cooling-Suspended State of Refrigeration-Facility
Unit>
[0126] While there is no need to cool the inside air, the
associated refrigeration-facility unit (60) is in the
cooling-suspended state. Specifically, if the inside air sucked
into each refrigeration-facility unit (60) has a temperature that
falls below the lower limit of a predetermined target range, the
refrigeration-facility controller (103) of the
refrigeration-facility unit (60) closes the refrigeration-facility
expansion valve (63) to change the state of the
refrigeration-facility unit (60) from the active state to the
cooling-suspended state. In this cooling-suspended state, the
refrigeration-facility fan (62) keeps operating. The
refrigeration-facility expansion valve (63) closed prevents the
refrigerant from being supplied from the second liquid connection
pipe (4) to the refrigeration-facility unit (60), thereby stopping
the cooling of air in the refrigeration-facility heat exchanger
(64).
[0127] If the inside air sucked into each refrigeration-facility
unit (60) has a temperature that exceeds the upper limit of the
predetermined target range, the refrigeration-facility controller
(103) opens the refrigeration-facility expansion valve (63) to
change the state of the refrigeration-facility unit (60) from the
cooling-suspended state to the active state. If the state of the
refrigeration-facility unit (60) is changed from the
cooling-suspended state to the active state, the cooling of air in
the refrigeration-facility heat exchanger (64) is restarted.
[0128] If all of the refrigeration-facility units (60) are in the
cooling-suspended state during operation of the second compressor
(22), the refrigerant pressure in the second gas connection pipe
(5) decreases. As a result, a value measured by the first
low-pressure sensor (73) decreases. If the value measured by the
first low-pressure sensor (73) thus falls below a predetermined
first reference value, the outdoor controller (101) stops the
second compressor (22).
[0129] If the state of at least one of the refrigeration-facility
units (60) is changed from the cooling-suspended state to the
active state during the stop of the second compressor (22), the
refrigerant pressure in the second gas connection pipe (5)
increases. As a result, the value measured by the first
low-pressure sensor (73) increases. If the value measured by the
first low-pressure sensor (73) thus exceeds a predetermined second
reference value, the outdoor controller (101) actuates the second
compressor (22).
[0130] --Control Operation of Hydraulic Pressure Controller--
[0131] A control operation performed by the hydraulic pressure
controller (85) of the intermediate unit (80) will be
described.
[0132] The hydraulic pressure controller (85) controls the first
and second valves (18) and (19) so that the refrigerant pressure in
the refrigeration-facility circuit (61) of each
refrigeration-facility unit (60) is kept at or below the
refrigerant pressure that can be allowed by the
refrigeration-facility circuit (61). The refrigerant pressure that
can be allowed by the refrigeration-facility circuit (61) is the
allowable pressure Pu of the refrigeration-facility unit (60). The
allowable pressure Pu of the refrigeration-facility unit (60) of
the present embodiment is 6 MPa (Pu=6 MPa). Note that the pressure
value used to describe the control operation of the hydraulic
pressure controller (85) is merely an example.
[0133] Here, if each refrigeration-facility unit (60) is in the
active state, the value measured by the refrigerant pressure sensor
(48) is slightly higher than the pressure of the refrigerant at the
inlet of the refrigeration-facility circuit (61). The reason for
this is that the refrigerant has its pressure gradually reduced,
while flowing through the second liquid-side trunk pipe (4b) and
the liquid-side branch pipe (4c). Meanwhile, the hydraulic pressure
controller (85) of the present embodiment controls the opening
degrees of the first and second valves (18) and (19) so that the
value Pk measured by the refrigerant pressure sensor (48) is lower
than the allowable pressure Pu of the refrigeration-facility units
(60), as will be described below. Thus, the hydraulic pressure
controller (85) controlling the first and second valves (18) and
(19) allows the pressure of the refrigerant flowing into the
refrigeration-facility circuit (61) of each refrigeration-facility
unit (60) to be kept below the allowable pressure Pu of the
refrigeration-facility unit (60).
[0134] <Control of First Valve>
[0135] An operation performed by the hydraulic pressure controller
(85) to control the opening degree of the first valve (18) will be
described with reference to the flowchart shown in FIG. 6. The
hydraulic pressure controller (85) repeatedly performs the control
operation shown in the flowchart of FIG. 6 at predetermined time
intervals (e.g., 30 seconds).
[0136] In the process performed in step ST1, the hydraulic pressure
controller (85) reads the value Pk measured by the refrigerant
pressure sensor (48), and compares the measured value Pk with a
first reference pressure PL1. The first reference pressure PL1 is
lower than the allowable pressure Pu of the refrigeration-facility
units (60) (PL1<Pu). The first reference pressure PL1 of the
present embodiment is 4.5 MPa.
[0137] In the process performed in step ST1, if the value Pk
measured by the refrigerant pressure sensor (48) is less than or
equal to the first reference pressure PL1 (Pk<PL1), the
hydraulic pressure controller (85) performs a process in step ST2.
On the other hand, if the value Pk measured by the refrigerant
pressure sensor (48) exceeds the first reference pressure PL1
(Pk>PL1), the hydraulic pressure controller (85) performs a
process in step ST3.
[0138] In the process performed in step ST2, the hydraulic pressure
controller (85) makes the first valve (18) fully open. In other
words, in the process performed in step ST2, the hydraulic pressure
controller (85) sets the opening degree of the first valve (18) at
a maximum value.
[0139] In the process performed in step ST3, the hydraulic pressure
controller (85) compares the value Pk measured by the refrigerant
pressure sensor (48) with a second reference pressure PL2. The
second reference pressure PL2 is lower than the allowable pressure
Pu of the refrigeration-facility units (60), and is higher than the
first reference pressure PL1 (PL1<PL2<Pu). The second
reference pressure PL2 of the present embodiment is 5.2 MPa.
[0140] In the process performed in step ST3, if the value Pk
measured by the refrigerant pressure sensor (48) is greater than or
equal to the second reference pressure PL2 (PL2<Pk), the
hydraulic pressure controller (85) performs a process in step ST4.
On the other hand, if the value Pk measured by the refrigerant
pressure sensor (48) falls below the second reference pressure PL2
(Pk<PL2), the hydraulic pressure controller (85) performs a
process in step ST5.
[0141] In the process performed in step ST4, the hydraulic pressure
controller (85) makes the first valve (18) fully closed. In other
words, in the process performed in step ST4, the hydraulic pressure
controller (85) sets the opening degree of the first valve (18) to
be substantially zero.
[0142] In the process performed in step ST5, the hydraulic pressure
controller (85) adjusts the opening degree of the first valve (18)
in accordance with the value Pk measured by the refrigerant
pressure sensor (48). Specifically, the hydraulic pressure
controller (85) performs proportional-integral-derivation (PID)
control to adjust the opening degree of the first valve (18) so
that the value Pk measured by the refrigerant pressure sensor (48)
becomes equal to a third reference pressure PL3. The third
reference pressure PL3 is greater than the first reference pressure
PL1, and is less than the second reference pressure PL2
(PL1<PL3<PL2). The third reference pressure PL3 of the
present embodiment is 4.8 MPa. Note that the hydraulic pressure
controller (85) may adjust the opening degree of the first valve
(18) using a control system except the PID control.
[0143] As described above, the hydraulic pressure controller (85)
adjusts the opening degree of the first valve (18) so that the
value Pk measured by the refrigerant pressure sensor (48) becomes
less than or equal to the second reference pressure PL2. As a
result, the pressure of the refrigerant to be supplied through the
second liquid connection pipe (4) from the intermediate unit (80)
to the refrigeration-facility units (60) in the active state is
kept below the allowable pressure Pu of the refrigeration-facility
units (60).
[0144] <Control of Second Valve>
[0145] An operation performed by the hydraulic pressure controller
(85) to control the opening degree of the second valve (19) will be
described with reference to FIG. 7.
[0146] The hydraulic pressure controller (85) reads the value Pk
measured by the refrigerant pressure sensor (48) at predetermined
time intervals (e.g., one second). The hydraulic pressure
controller (85) sets the opening degree of the second valve (19) in
accordance with the value Pk measured by the refrigerant pressure
sensor (48).
[0147] If the value Pk measured by the refrigerant pressure sensor
(48) is less than a fourth reference pressure PL4 (Pk<PL4), the
hydraulic pressure controller (85) makes the second valve (19)
fully closed. In other words, in this case, the hydraulic pressure
controller (85) sets the opening degree of the second valve (19) to
be substantially zero. The fourth reference pressure PL4 is greater
than the second reference pressure PL2, and is less than the
allowable pressure Pu (PL2<PL4<Pu). The fourth reference
pressure PL4 of the present embodiment is 5.4 MPa.
[0148] If the value Pk measured by the refrigerant pressure sensor
(48) is greater than or equal to a fifth reference pressure PL5
(PL5<Pk), the hydraulic pressure controller (85) makes the
second valve (19) fully open. In other words, in this case, the
hydraulic pressure controller (85) sets the opening degree of the
second valve (19) at a maximum value. The fifth reference pressure
PL5 is greater than the fourth reference pressure PL4, and is less
than the allowable pressure Pu (PL4<PL5<Pu). The fifth
reference pressure PL5 of the present embodiment is 5.8 MPa.
[0149] If the value Pk measured by the refrigerant pressure sensor
(48) is greater than or equal to the fourth reference pressure PL4
and less than or equal to the fifth reference pressure PL5 (PL4 Pk
PL5), the hydraulic pressure controller (85) sets the opening
degree of the second valve (19) to be a value proportional to the
value Pk measured by the refrigerant pressure sensor (48).
[0150] Specifically, the hydraulic pressure controller (85) sets
the opening degree of the second valve (19) to be a value
proportional to the difference between the value Pk measured by the
refrigerant pressure sensor (48) and the fourth reference pressure
PL4 (Pk-PL4). If the value Pk measured by the refrigerant pressure
sensor (48) is equal to the fourth reference pressure PL4 (Pk=PL4),
the hydraulic pressure controller (85) sets the opening degree of
the second valve (19) to be substantially zero. On the other hand,
if the value Pk measured by the refrigerant pressure sensor (48) is
equal to the fifth reference pressure PL5 (Pk=PL5), the hydraulic
pressure controller (85) sets the opening degree of the second
valve (19) at a maximum value.
[0151] As described above, if the value Pk measured by the
refrigerant pressure sensor (48) is greater than or equal to the
second reference pressure PL2 (PL2<Pk), the hydraulic pressure
controller (85) makes the first valve (18) fully closed. The fourth
reference pressure PL4 is higher than the second reference pressure
PL2 (PL2<PL4). Thus, if the value Pk measured by the refrigerant
pressure sensor (48) is greater than the second reference pressure
PL2 even with the first valve (18) closed, the hydraulic pressure
controller (85) opens the second valve (19).
[0152] --Refrigerant Pressure Acting on Refrigeration-Facility
Expansion Valve of Refrigeration-Facility Unit--
[0153] If the refrigeration-facility units (60) are in the active
state, the hydraulic pressure controller (85) adjusts the opening
degree of the first valve (18) so that the value Pk measured by the
refrigerant pressure sensor (48) becomes less than or equal to the
second reference pressure PL2. Thus, if the refrigeration-facility
units (60) are in the active state, the refrigerant pressure acting
on the refrigeration-facility expansion valves (63) is kept below
the allowable pressure Pu of the refrigeration-facility units
(60).
[0154] On the other hand, if the temperature of the inside air
falls within a set temperature range, the associated
refrigeration-facility controller (103) closes the associated
refrigeration-facility expansion valve (63) to change the state of
the associated refrigeration-facility unit (60) from the active
state to the cooling-suspended state. If all of the
refrigeration-facility units (60) are in the cooling-suspended
state, the refrigerant pressure in the second liquid-side trunk
pipe (4b) and the liquid-side branch pipes (4c) increases. As a
result, the value Pk measured by the refrigerant pressure sensor
(48) increases. If the value Pk measured by the refrigerant
pressure sensor (48) then increases to a value greater than or
equal to the second reference pressure PL2, the hydraulic pressure
controller (85) closes the first valve (18).
[0155] As can be seen, if all of the refrigeration-facility units
(60) are in the cooling-suspended state, the refrigeration-facility
expansion valves (63) of all of the refrigeration-facility units
(60) and the first valve (18) of the intermediate unit (80) are
closed. In this state, a portion of the refrigerant circuit (6)
between the refrigeration-facility expansion valves (63) and the
first valve (18) (the portion indicated by the thick line in FIG.
5) encloses the refrigerant. If the temperatures around the second
liquid-side trunk pipe (4b) and the liquid-side branch pipes (4c)
are relatively high, the pressure of the refrigerant enclosed in
the portion of the refrigerant circuit (6) between the
refrigeration-facility expansion valves (63) and the first valve
(18) (the portion indicated by the thick line in FIG. 5) increases.
This may cause the refrigerant pressure acting on the
refrigeration-facility expansion valves (63) to exceed the
allowable pressure Pu of the refrigeration-facility units (60)
unless some countermeasure is taken.
[0156] To address this problem, the hydraulic pressure controller
(85) of the intermediate unit (80) of the present embodiment
controls the opening degree of the second valve (19). Specifically,
if the value Pk measured by the refrigerant pressure sensor (48)
exceeds the fourth reference pressure PL4, the hydraulic pressure
controller (85) opens the second valve (19). The open second valve
(19) allows a portion of the refrigerant present in the second
liquid-side trunk pipe (4b) and the liquid-side branch pipes (4c)
to flow through the joint pipe (83) to the gas-side pipe (82) and
the gas connection pipe (5). As a result, the refrigerant pressure
in the second liquid-side trunk pipe (4b) and the liquid-side
branch pipes (4c) decreases.
[0157] As can be seen, in the refrigeration apparatus (1) including
the intermediate unit (80) of the present embodiment, even if all
of the refrigeration-facility units (60) are in the
cooling-suspended state, the refrigerant pressure acting on the
refrigeration-facility expansion valves (63) of the
refrigeration-facility units (60) is kept below the allowable
pressure Pu of the refrigeration-facility units (60).
[0158] Here, in principle, the second valve (19) opens when all of
the refrigeration-facility units (60) are in the cooling-suspended
state and the second compressor (22) is stopped. If the second
valve (19) opens during operations of the first and third
compressors (21) and (23), the refrigerant present in the second
liquid-side trunk pipe (4b) and the liquid-side branch pipes (4c)
is drawn by the first compressor (21). Specifically, the
refrigerant present in the second liquid-side trunk pipe (4b) and
the liquid-side branch pipes (4c) flows through the joint pipe
(83), the gas-side pipe (82), and the gas connection pipe (5) in
this order into the outdoor circuit (11), and joins the refrigerant
discharged from the third compressor (23) after passing through the
second bypass pipe (24b). The resultant refrigerant is subsequently
sucked into the first compressor (21) after passing through the
intercooler (17).
[0159] In some cases, the hydraulic controller (85) opens the
second valve (19) while all of the compressors (21, 22, 23) are
stopped. In such a case, the first compressor (21) may be started,
and the refrigerant present in the second liquid-side trunk pipe
(4b) and the liquid-side branch pipes (4c) may be drawn into the
first compressor (21). This causes the refrigerant present in the
second liquid-side trunk pipe (4b) and the liquid-side branch pipes
(4c) to turn into the form of single-phase gas while passing
through the intercooler (17), and to be then sucked into the first
compressor (21).
[0160] --Feature (1) of Embodiment--
[0161] The intermediate unit (80) of the present embodiment is
provided between the heat source unit (10) and the
refrigeration-facility units (60), which are connected together
through the liquid connection pipe (4) and the gas connection pipe
(5) to form part of the refrigeration apparatus (1). The
intermediate unit (80) includes the liquid-side pipe (81), the
first valve (18), the refrigerant pressure sensor (48), and the
hydraulic pressure controller (85). The liquid-side pipe (81) is
connected to the liquid connection pipe (4). The first valve (18)
is a valve provided for the liquid-side pipe (81) and having a
variable opening degree. The refrigerant pressure sensor (48) is
disposed in a portion of the liquid-side pipe (81) closer to the
refrigeration-facility units (60) than the first valve (18) is, and
measures the pressure of the refrigerant flowing through the
liquid-side pipe (81). The hydraulic pressure controller (85)
adjusts the opening degree of the first valve (18) based on the
value measured by the refrigerant pressure sensor (48).
[0162] In the refrigeration apparatus (1) of the present
embodiment, the refrigerant sent out from the heat source unit (10)
and flowing through the liquid connection pipe (4) is supplied to
the refrigeration-facility units (60) after passing through the
liquid-side pipe (81) of the intermediate unit (80). The hydraulic
pressure controller (85) changing the opening degree of the first
valve (18) for the liquid-side pipe (81) triggers a change in the
pressure of the refrigerant that has passed through the first valve
(18). The hydraulic pressure controller (85) changing the opening
degree of the first valve (18) based on the value measured by the
refrigerant pressure sensor (48) triggers a change in the pressure
of the refrigerant to be sent from the intermediate unit (80) to
the refrigeration-facility units (60).
[0163] In the refrigeration apparatus (1) of the present
embodiment, the intermediate unit (80) adjusts the pressure of the
refrigerant flowing into the refrigeration-facility units (60). For
this reason, even if the heat source unit (10) does not perform
control with consideration given to the allowable pressure of the
refrigeration-facility units (60), the refrigeration-facility units
(60) having an allowable pressure that is lower than that of the
heat source unit (10) can be connected to the heat source unit
(10). Thus, according to the present embodiment, various models of
refrigeration-facility units can be connected to the heat source
unit (10) without complicating the manner of control performed by
the heat source unit (10).
[0164] --Feature (2) of Embodiment--
[0165] The intermediate unit (80) of the present embodiment
includes the gas-side pipe (82), the joint pipe (83), and the
second valve (19). The gas-side pipe (82) is connected to the gas
connection pipe (5). The joint pipe (83) connects the portion of
the liquid-side pipe (81) closer to the refrigeration-facility
units (60) than the first valve (18) is and the gas-side pipe (82)
together. The second valve (19) is provided for the joint pipe
(83).
[0166] Here, while the refrigeration-facility expansion valves (63)
of the refrigeration-facility units (60) and the first valve (18)
of the intermediate unit (80) are all closed, the refrigerant is
enclosed in a portion of the liquid connection pipe (4) between the
intermediate unit (80) and the refrigeration-facility units (60).
If this state occurs while the air temperature around the liquid
connection pipe (4) is high, the internal pressure of the liquid
connection pipe (4) increases. This may damage the
refrigeration-facility units (60).
[0167] To address this problem, the intermediate unit (80) of the
present embodiment includes the joint pipe (83) connecting the
liquid-side pipe (81) and the gas-side pipe (82) together and
provided with the second valve (19). While the second valve (19) is
open, the portion of the liquid connection pipe (4) between the
intermediate unit (80) and the refrigeration-facility units (60)
communicates with the gas connection pipe (5) via the joint pipe
(83). This can substantially prevent the internal pressure of the
liquid connection pipe (4) from increasing excessively while the
refrigeration-facility expansion valves (63) of the
refrigeration-facility units (60) and the first valve (18) of the
intermediate unit (80) are all closed. As a result, the
refrigeration-facility units (60) can be substantially prevented
from being damaged.
[0168] --Feature (3) of Embodiment--
[0169] In the intermediate unit (80) of the present embodiment, the
hydraulic pressure controller (85) adjusts the opening degree of
the first valve (18) so that the value measured by the refrigerant
pressure sensor (48) becomes less than or equal to the second
reference pressure PL2. If the value measured by the refrigerant
pressure sensor (48) exceeds "the fourth reference pressure PL4
higher than the second reference pressure PL2" even with the first
valve (18) closed, the hydraulic pressure controller (85) opens the
second valve (19).
[0170] The hydraulic pressure controller (85) of the intermediate
unit (80) of the present embodiment controls the first and second
valves (18) and (19). The hydraulic pressure controller (85)
controlling the first valve (18) allows the pressure of the
refrigerant that is about to be supplied from the intermediate unit
(80) to the refrigeration-facility units (60) to be substantially
kept at or below the second reference pressure PL2. The hydraulic
pressure controller (85) controlling the second valve (19)
substantially prevents the internal pressure of the portion of the
liquid connection pipe (4) between the intermediate unit (80) and
the refrigeration-facility units (60) from increasing excessively
even while the first valve (18) is closed.
[0171] --Feature (4) of Embodiment--
[0172] The intermediate unit (80) of the present embodiment is
installed indoors, and is connected to the heat source unit (10)
installed outdoors.
[0173] The intermediate unit (80) of the present embodiment is
placed indoors. Thus, in the summer when the outdoor air
temperature is high, the air temperature around the portion of the
liquid connection pipe (4) between the intermediate unit (80) and
the refrigeration-facility units (60) is lower than that outdoors.
This can substantially prevent the internal pressure of the portion
of the liquid connection pipe (4) between the intermediate unit
(80) and the refrigeration-facility units (60) from increasing
while the refrigeration-facility expansion valves (63) of the
refrigeration-facility units (60) and the first valve (18) of the
intermediate unit (80) are all closed.
[0174] The intermediate unit (80) may be arranged in the indoor
space where the refrigeration-facility units (60) are also
arranged. The refrigeration-facility units (60) are typically
installed in an indoor space to be air-conditioned by an
air-conditioning unit (50). For example, even if the outdoor air
temperature is relatively high in the summer, the air temperature
in the indoor space including the intermediate unit (80) and the
refrigeration-facility units (60) is lower than the outdoor air
temperature. Thus, the intermediate unit (80) installed indoors
could substantially prevent the internal pressure of the portion of
the liquid connection pipe (4) between the intermediate unit (80)
and the refrigeration-facility units (60) from increasing while the
refrigeration-facility expansion valves (63) of the
refrigeration-facility units (60) and the first valve (18) of the
intermediate unit (80) are all closed.
[0175] --Feature (5) of Embodiment--
[0176] The refrigeration apparatus (1) of the present embodiment
includes the intermediate unit (80), the heat source unit (10), the
refrigeration-facility units (60), the liquid connection pipe (4),
and the gas connection pipe (5). The liquid connection pipe (4) and
the gas connection pipe (5) connect the intermediate unit (80), the
heat source unit (10), and the refrigeration-facility units (60)
together to form the refrigerant circuit (6).
[0177] In the refrigeration apparatus (1) of the present
embodiment, the intermediate unit (80) is disposed between the heat
source unit (10) and the refrigeration-facility units (60) in the
refrigerant circuit (6). The liquid-side pipe (81) of the
intermediate unit (80) is connected to the liquid connection pipe
(4). Changing the opening degree of the first valve (18) of the
intermediate unit (80) triggers a change in the pressure of the
refrigerant to be sent through the liquid connection pipe (4) from
the intermediate unit (80) to the refrigeration-facility units
(60).
[0178] --Feature (6) of Embodiment--
[0179] The refrigeration apparatus (1) of the present embodiment
includes the intermediate unit (80), the heat source unit (10), the
refrigeration-facility units (60), the liquid connection pipe (4),
and the gas connection pipe (5). The liquid connection pipe (4)
includes the liquid-side trunk pipes (4a, 4b) connected to the heat
source unit (10), and the plurality of liquid-side branch pipes
(4c) each connecting an associated one of the
refrigeration-facility units (60) to the liquid-side trunk pipes
(4a, 4b). The gas connection pipe (5) includes the gas-side trunk
pipes (5a, 5b) connected to the heat source unit (10), and the
plurality of gas-side branch pipes (5c) each connecting an
associated one of the refrigeration-facility units (60) to the
gas-side trunk pipes (5a, 5b). The liquid-side pipe (81) of the
intermediate unit (80) is connected to the liquid-side trunk pipes
(4a, 4b) of the liquid connection pipe (4). The gas-side pipe (82)
of the intermediate unit (80) is connected to the gas-side trunk
pipes (5a, 5b) of the gas connection pipe (5).
[0180] In the refrigeration apparatus (1) of the present
embodiment, the plurality of refrigeration-facility units (60) are
connected through the liquid connection pipe (4) and the gas
connection pipe (5) to the heat source unit (10). The intermediate
unit (80) is connected to the liquid-side trunk pipes (4a, 4b) of
the liquid connection pipe (4) and the gas-side trunk pipes (5a,
5b) of the gas connection pipe (5). The refrigerant that has flowed
from the heat source unit (10) into the liquid-side trunk pipes
(4a, 4b) of the liquid connection pipe (4) passes through the first
valve (18) of the intermediate unit (80), and is then distributed
among the plurality of refrigeration-facility units (60).
[0181] --First Variation of Embodiment--
[0182] The second valve (19) of the intermediate unit (80) of the
foregoing embodiment may be an on-off valve that selectively
switches between the fully-closed state and the fully-open state. A
second valve (19) of this variation is an electromagnetic valve
including a solenoid that drives its valve body.
[0183] As shown in FIG. 8, when the second valve (19) is in the
fully-closed state, and the value Pk measured by the refrigerant
pressure sensor (48) reaches the fifth reference pressure PL5
(Pk=PL5), a hydraulic pressure controller (85) of this variation
changes the state of the second valve (19) from the fully-closed
state to the fully-open state. When the second valve (19) is in the
fully-open state, and the value Pk measured by the refrigerant
pressure sensor (48) reaches the fourth reference pressure PL4
(Pk=PL4), the hydraulic pressure controller (85) of this variation
changes the state of the second valve (19) from the fully-open
state to the fully-closed state. The fourth and fifth reference
pressures PL4 and PL5 are respectively equal to those set when the
second valve (19) is a control valve having a variable opening
degree.
[0184] --Second Variation of Embodiment--
[0185] The hydraulic pressure controller (85) of the foregoing
embodiment may set the fourth reference pressure PL4 at a value
slightly less than the second reference pressure PL2 (PL4<PL2).
Even in such a case, the fourth reference pressure PL4 is set at a
value greater than the first reference pressure PL1 (PL1<PL4).
It is possible for a second valve (19) of an intermediate unit (80)
of this variation to start opening before the first valve (18)
falls into the fully-closed state.
[0186] --Third Variation of Embodiment--
[0187] The intermediate unit (80) of the foregoing embodiment may
include a pressure input section (86). The pressure input section
(86) is a member to be operated by an operator to input information
on the allowable pressure Pu of the refrigeration-facility units
(60) to the hydraulic pressure controller (85). Examples of the
pressure input section (86) include a DIP switch and a numeric
keypad for input of numerals.
[0188] As shown in FIG. 9, a pressure input section (86) of an
intermediate unit (80) of this variation is electrically connected
to a hydraulic pressure controller (85) via a communication line or
any other similar element. Information input to the pressure input
section (86) is transmitted to the hydraulic pressure controller
(85), and is recorded in a memory device of the hydraulic pressure
controller (85). Information to be input to the pressure input
section (86) may include the allowable pressure Pu of the
refrigeration-facility units (60) or a symbol such as a number
corresponding to the allowable pressure Pu.
[0189] The hydraulic pressure controller (85) of this variation
sets the reference pressures PL1 to PL5 based on the information
input to the pressure input section (86), and controls the opening
degrees of the first and second valves (18) and (19) with reference
to the set reference pressures PL1 to PL5.
[0190] --Fourth Variation of Embodiment--
[0191] The intermediate unit (80) of the foregoing embodiment may
omit the gas-side pipe (82), the joint pipe (83), and the second
valve (19). For example, if the refrigeration apparatus (1) is
installed in a cold climate area where the air temperature in the
summer is not so high, the refrigerant pressure in the second
liquid-side trunk pipe (4b) and the liquid-side branch pipes (4c)
may be kept at or below the allowable pressure of the
refrigeration-facility units (60) even with the
refrigeration-facility expansion valves (63) of all of the
refrigeration-facility units (60) and the first valve (18) of the
intermediate unit (80) closed. Thus, the intermediate unit (80)
forming part of the refrigeration apparatus (1) installed in the
cold climate area may omit the gas-side pipe (82), the joint pipe
(83), and the second valve (19). An intermediate unit (80) of this
variation is connected only to a liquid connection pipe (4) but is
not connected to a gas connection pipe (5).
[0192] --Fifth Variation of Embodiment--
[0193] The refrigeration apparatus (1) of the foregoing embodiment
may omit the air-conditioning units (50) while including the heat
source unit (10) and the refrigeration-facility units (60). A
refrigeration apparatus (1) of this variation exclusively cools
inside air. A heat source unit (10) forming part of the
refrigeration apparatus (1) of this variation omits a third
compressor (23).
[0194] --Sixth Variation of Embodiment--
[0195] The utilization units of the refrigeration apparatus (1) of
the foregoing embodiment are not limited to the air-conditioning
units (50) configured to condition air in a room. The utilization
units of the refrigeration apparatus (1) of the foregoing
embodiment may be configured to heat or cool water using a
refrigerant. A utilization unit of this variation includes a heat
exchanger configured to exchange heat between a refrigerant and
water, as a utilization heat exchanger.
[0196] While the embodiment and variations thereof have been
described above, it will be understood that various changes in form
and details may be made without departing from the spirit and scope
of the claims. The embodiment and the variations thereof may be
combined and replaced with each other without deteriorating
intended functions of the present disclosure.
INDUSTRIAL APPLICABILITY
[0197] As can be seen from the foregoing description, the present
disclosure is useful for an intermediate unit for a refrigeration
apparatus, and a refrigeration apparatus including the intermediate
unit.
EXPLANATION OF REFERENCES
[0198] 1 Refrigeration Apparatus [0199] 4 Liquid Connection Pipe
[0200] 4a First Liquid-Side Trunk Pipe [0201] 4b Second Liquid-Side
Trunk Pipe [0202] 4c Liquid-Side Branch Pipe [0203] 5 Gas
Connection Pipe [0204] 5a First Gas-Side Trunk Pipe [0205] 5b
Second Gas-Side Trunk Pipe [0206] 5c Gas-Side Branch Pipe [0207] 10
Heat Source Unit [0208] 18 First Valve [0209] 19 Second Valve
[0210] 48 Refrigerant Pressure Sensor [0211] 60
Refrigeration-Facility Unit (Utilization Unit) [0212] 80
Intermediate Unit [0213] 81 Liquid-Side Pipe [0214] 82 Gas-Side
Pipe [0215] 83 Joint Pipe [0216] 85 Hydraulic Pressure Controller
(Controller)
* * * * *