U.S. patent application number 13/132836 was filed with the patent office on 2011-09-29 for refrigerating apparatus.
Invention is credited to Shuji Furui, Kazuhiro Furusho, Ikuhiro Iwata, Michio Moriwaki.
Application Number | 20110232325 13/132836 |
Document ID | / |
Family ID | 42233085 |
Filed Date | 2011-09-29 |
United States Patent
Application |
20110232325 |
Kind Code |
A1 |
Furui; Shuji ; et
al. |
September 29, 2011 |
REFRIGERATING APPARATUS
Abstract
In a refrigerant circuit (5) of an air conditioner (1), a
single-stage compression refrigeration cycle is performed. In the
refrigerant circuit (5), a second heat exchanger (40) is provided
downstream a first heat exchanger (30). In the first heat exchanger
(30), high-pressure refrigerant of a high-pressure flow path (31)
is cooled by exchanging heat with first intermediate-pressure
refrigerant of an intermediate-pressure flow path (32). First
intermediate-pressure gas refrigerant generated in the first heat
exchanger (30) is supplied to a first compression mechanism (71).
Second intermediate-pressure refrigerant having a pressure lower
than that of the first intermediate-pressure refrigerant is
supplied to an intermediate-pressure flow path (42) of the second
heat exchanger (40). In the second heat exchanger (40),
high-pressure refrigerant of a high-pressure flow path (41) is
further cooled by exchanging heat with the second
intermediate-pressure refrigerant of the intermediate-pressure flow
path (42). Second intermediate-pressure gas refrigerant generated
in the second heat exchanger (40) is supplied to a second
compression mechanism (72).
Inventors: |
Furui; Shuji; (Osaka,
JP) ; Furusho; Kazuhiro; (Osaka, JP) ;
Moriwaki; Michio; (Osaka, JP) ; Iwata; Ikuhiro;
(Osaka, JP) |
Family ID: |
42233085 |
Appl. No.: |
13/132836 |
Filed: |
December 2, 2009 |
PCT Filed: |
December 2, 2009 |
PCT NO: |
PCT/JP2009/006561 |
371 Date: |
June 3, 2011 |
Current U.S.
Class: |
62/510 |
Current CPC
Class: |
F25B 1/10 20130101; F25B
13/00 20130101; F25B 2313/0272 20130101; F25B 2400/23 20130101;
F25B 1/04 20130101; F25B 2400/075 20130101; F25B 2313/02741
20130101; F25B 2400/13 20130101 |
Class at
Publication: |
62/510 |
International
Class: |
F25B 1/10 20060101
F25B001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 5, 2008 |
JP |
2008-311505 |
Sep 30, 2009 |
JP |
2009-227151 |
Claims
1. A refrigerating apparatus, comprising: a refrigerant circuit
including a radiator and an evaporator and performing a
refrigeration cycle; and a first compression mechanism and a second
compression mechanism each including a compression chamber, wherein
each of the first compression mechanism and the second compression
mechanism sucks low-pressure refrigerant into the compression
chamber, and compresses the low-pressure refrigerant to a high
pressure level, and the refrigerant circuit includes an enthalpy
reducing unit for reducing an enthalpy of refrigerant flowing from
the radiator to the evaporator by generating first
intermediate-pressure gas refrigerant and second
intermediate-pressure gas refrigerant having a pressure lower than
that of the first intermediate-pressure gas refrigerant, a first
injection path for supplying the first intermediate-pressure gas
refrigerant generated in the enthalpy reducing unit to the
compression chamber of the first compression mechanism in the
middle of a compression process, and a second injection path for
supplying the second intermediate-pressure gas refrigerant
generated in the enthalpy reducing unit to the compression chamber
of the second compression mechanism in the middle of a compression
process.
2. A refrigerating apparatus, comprising: a refrigerant circuit
including a radiator and an evaporator and performing a
refrigeration cycle; and a first compression mechanism and a second
compression mechanism each including a compression chamber, wherein
the second compression mechanism sucks low-pressure refrigerant
into the compression chamber and compresses the low-pressure
refrigerant, and the first compression mechanism sucks the
refrigerant discharged from the second compression mechanism into
the compression chamber and compresses the refrigerant, and the
refrigerant circuit includes an enthalpy reducing unit for reducing
an enthalpy of refrigerant flowing from the radiator to the
evaporator by generating first intermediate-pressure gas
refrigerant and second intermediate-pressure gas refrigerant having
a pressure lower than that of the first intermediate-pressure gas
refrigerant, a second injection path for supplying the second
intermediate-pressure gas refrigerant generated in the enthalpy
reducing unit to the compression chamber of the second compression
mechanism in the middle of a compression process, and a first
injection path for supplying the first intermediate-pressure gas
refrigerant generated in the enthalpy reducing unit to the
compression chamber of the first compression mechanism in the
middle of a compression process, or to an inlet side of the first
compression mechanism.
3. A refrigerating apparatus, comprising: a refrigerant circuit
including a radiator and an evaporator and performing a
refrigeration cycle; and a first compression mechanism and a second
compression mechanism each including a compression chamber, wherein
the second compression mechanism sucks low-pressure refrigerant
into the compression chamber and compresses the low-pressure
refrigerant, and the first compression mechanism sucks the
refrigerant discharged from the second compression mechanism into
the compression chamber and compresses the refrigerant, and the
refrigerant circuit includes an enthalpy reducing unit for reducing
an enthalpy of refrigerant flowing from the radiator to the
evaporator by generating first intermediate-pressure gas
refrigerant and second intermediate-pressure gas refrigerant having
a pressure lower than that of the first intermediate-pressure gas
refrigerant, a second injection path for supplying the second
intermediate-pressure gas refrigerant generated in the enthalpy
reducing unit to an inlet side of the first compression mechanism,
and a first injection path for supplying the first
intermediate-pressure gas refrigerant generated in the enthalpy
reducing unit to the compression chamber of the first compression
mechanism in the middle of a compression process.
4. The refrigerating apparatus of any one of claims 1-3, wherein in
the refrigerant circuit, a portion of the refrigerant circuit from
an outlet of the radiator to an inlet of the evaporator forms a
main path, and the enthalpy reducing unit includes a branched path
which is connected to the main path and into which a part of
refrigerant flowing through the main path flows, an expansion
mechanism for expanding the refrigerant flowing into the branched
path to generate first intermediate-pressure refrigerant and second
intermediate-pressure refrigerant having a pressure lower than that
of the first intermediate-pressure refrigerant, a first heat
exchanger which is connected to the main path downstream the
radiator to exchange heat between the refrigerant flowing through
the main path and the first intermediate-pressure refrigerant,
which cools the refrigerant flowing through the main path, and
which generates the first intermediate-pressure gas refrigerant by
evaporating the first intermediate-pressure refrigerant, and a
second heat exchanger which is connected to the main path between
the first heat exchanger and the evaporator to exchange heat
between the refrigerant flowing through the main path and the
second intermediate-pressure refrigerant, which cools the
refrigerant flowing through the main path, and which generates the
second intermediate-pressure gas refrigerant by evaporating the
second intermediate-pressure refrigerant.
5. The refrigerating apparatus of claim 4, wherein the branched
path of the enthalpy reducing unit includes a first branched pipe
which is connected to the main path between the radiator and the
first heat exchanger, and which supplies refrigerant flowing from
the main path to the first heat exchanger, and a second branched
pipe which is connected to the main path between the first heat
exchanger and the second heat exchanger, and which supplies the
refrigerant flowing from the main path to the second heat
exchanger, and the expansion mechanism of the enthalpy reducing
unit includes a first expansion valve which is provided in the
first branched pipe, and which generates the first
intermediate-pressure refrigerant by expanding refrigerant flowing
into the first branched pipe, and a second expansion valve which is
provided in the second branched pipe, and which generates the
second intermediate-pressure refrigerant by expanding refrigerant
flowing into the second branched pipe.
6. The refrigerating apparatus of claim 4, wherein the branched
path of the enthalpy reducing unit includes a first branched pipe
which is connected to the main path between the radiator and the
first heat exchanger, and which supplies refrigerant flowing from
the main path to the first heat exchanger, and a second branched
pipe which is connected to the first branched pipe, and which
supplies refrigerant flowing from the first branched pipe to the
second heat exchanger, and the expansion mechanism of the enthalpy
reducing unit includes a first expansion valve which is provided in
the first branched pipe, and which generates the first
intermediate-pressure refrigerant by expanding refrigerant flowing
into the first branched pipe, and a second expansion valve which is
provided in the second branched pipe, and which generates the
second intermediate-pressure refrigerant by expanding refrigerant
flowing into the second branched pipe.
7. The refrigerating apparatus of any one of claims 1-3, wherein
the enthalpy reducing unit includes a first expansion valve for
expanding high-pressure refrigerant flowing out from the radiator,
a first gas-liquid separator for separating the refrigerant flowing
out from the first expansion valve in a gas-liquid two-phase state
into gas refrigerant and liquid refrigerant, and supplying the gas
refrigerant to the first injection path as the first
intermediate-pressure gas refrigerant, a second expansion valve for
expanding the liquid refrigerant flowing out from the first
gas-liquid separator, and a second gas-liquid separator for
separating the refrigerant flowing out from the second expansion
valve in the gas-liquid two-phase state into gas refrigerant and
liquid refrigerant, supplying the gas refrigerant to the second
injection path as the second intermediate-pressure gas refrigerant,
and supplying the liquid refrigerant to the evaporator.
8. The refrigerating apparatus of any one of claims 1-3, wherein
the first compression mechanism and the second compression
mechanism are provided in a single compressor, and the compressor
includes a single drive shaft engaged with both of the first
compression mechanism and the second compression mechanism.
9. The refrigerating apparatus of any one of claims 1-3, wherein
the first compression mechanism is provided in a first compressor,
and the second compression mechanism is provided in a second
compressor, and the first compressor includes a drive shaft engaged
with the first compression mechanism, and the second compressor
includes a drive shaft engaged with the second compression
mechanism.
Description
TECHNICAL FIELD
[0001] The present invention relates to a refrigerating apparatus
in which a gas injection is performed to supply
intermediate-pressure gas refrigerant to a compressor.
BACKGROUND ART
[0002] Conventionally, a refrigerating apparatus has been known, in
which a vapor compression refrigeration cycle and a so-called "gas
injection" are performed. In the refrigerating apparatus in which
the gas injection is performed, intermediate-pressure gas
refrigerant is injected to a compression chamber of a compressor in
the middle of a compression process.
[0003] For example, Patent Document 1 discloses an air conditioner
configured by a refrigerating apparatus in which a gas injection is
performed. In such an air conditioner, an intercooler is provided
in a refrigerant circuit (see FIG. 1). In the intercooler,
high-pressure liquid refrigerant flowing from a condenser (indoor
heat exchanger in a heating operation) is cooled by exchanging heat
with intermediate-pressure refrigerant which is generated by
branching and expanding a part of the high-pressure liquid
refrigerant. Then, the high-pressure refrigerant cooled in the
intercooler is supplied to an evaporator (outdoor heat exchanger in
the heating operation). The intermediate-pressure refrigerant
evaporated in the intercooler (intermediate-pressure gas
refrigerant) is supplied to a compression chamber of a compressor
in the middle of a compression process.
[0004] In addition, Patent Document 2 also discloses an air
conditioner configured by a refrigerating apparatus in which a gas
injection is performed. In a refrigerant circuit of such an air
conditioner, a gas-liquid separator is provided between two
expansion valves. Intermediate-pressure refrigerant in a gas-liquid
two-phase state, which is expanded when passing through the
expansion valve upstream the gas-liquid separator flows into the
gas-liquid separator. In the gas-liquid separator, the
intermediate-pressure refrigerant flowing into the gas-liquid
separator is separated into gas refrigerant and liquid refrigerant.
Then, the intermediate-pressure liquid refrigerant in the
gas-liquid separator is expanded when passing through the expansion
valve downstream the gas-liquid separator, and is sent to an
evaporator. The intermediate-pressure gas refrigerant in the
gas-liquid separator is supplied to a compression chamber of a
compressor in the middle of a compression process.
[0005] Further, Patent Document 3 discloses a refrigerating
apparatus in which a multiple-stage compression refrigeration cycle
is performed. In a refrigerant circuit of such a refrigerating
apparatus, a plurality of compressors are connected in series.
Refrigerant discharged from the low-pressure compressor is sucked
into the high-pressure compressor, and is further compressed. In
addition, in the refrigerant circuit, intermediate-pressure gas
refrigerant is supplied to a pipe connecting between the
low-pressure and high-pressure compressors in order to reduce an
enthalpy of refrigerant sucked into the high-pressure compressor.
Further, FIG. 2 of Patent Document 3 illustrates a refrigerant
circuit in which a four-stage compression refrigeration cycle is
performed. In such a refrigerant circuit, three types of
intermediate-pressure gas refrigerants with different pressures are
supplied to pipes connecting the compressors of the four stages
together.
CITATION LIST
Patent Document
[0006] PATENT DOCUMENT 1: Japanese Patent Publication No.
2004-183913 [0007] PATENT DOCUMENT 2: Japanese Patent Publication
No. H11-093874 [0008] PATENT DOCUMENT 3: Japanese Patent
Publication No. 2002-188865
SUMMARY OF THE INVENTION
Technical Problem
[0009] In a refrigerant circuit of the refrigerating apparatus in
which the gas injection is performed, the compressor compresses
low-pressure refrigerant sucked from an evaporator and
intermediate-pressure gas refrigerant injected to the compression
chamber in the middle of the compression process, and discharges
the compressed refrigerant to a condenser. Thus, in the refrigerant
circuit, a mass flow rate of refrigerant in the condenser is
greater than a mass flow rate of refrigerant in the evaporator.
[0010] A greater mass flow rate of refrigerant in the condenser
results in a greater amount of heat released from refrigerant
(i.e., a heat dissipation amount of refrigerant) in the condenser.
Thus, if a mass flow rate of intermediate-pressure gas refrigerant
supplied to the compressor is increased, the mass flow rate of
refrigerant in the condenser can be increased without increasing a
mass flow rate of low-pressure refrigerant sucked into the
compressor from the evaporator. In order to increase the mass flow
rate of intermediate-pressure gas refrigerant supplied to the
compressor, the pressure of the intermediate-pressure gas
refrigerant may be increased to increase the density of the
intermediate-pressure gas refrigerant flowing into the compression
chamber.
[0011] However, a higher refrigerant pressure results in a higher
refrigerant saturation temperature. For such a reason, if the
pressure of the intermediate-pressure gas refrigerant generated in
the intercooler of Patent Document 1 or the gas-liquid separator of
Patent Document 2 is increased, an enthalpy of refrigerant sent
from the intercooler or the gas-liquid separator to the evaporator
is increased. As a result, an amount of heat absorbed by
refrigerant (i.e., heat absorption amount of refrigerant) in the
evaporator is decreased.
[0012] Thus, in the conventional refrigerating apparatus in which
the gas injection is performed, it is difficult to ensure both of
the heat dissipation amount of refrigerant in the condenser and the
heat absorption amount of refrigerant in the evaporator.
[0013] The present invention has been made in view of the
foregoing, and it is an objective of the present invention to
ensure both of a heat dissipation amount of refrigerant in a
condenser and a heat absorption amount of refrigerant in an
evaporator in a refrigerating apparatus in which an gas injection
is performed.
Solution to the Problem
[0014] A first aspect of the invention is intended for a
refrigerating apparatus including a refrigerant circuit (5)
including a radiator and an evaporator and performing a
refrigeration cycle, and a first compression mechanism (71) and a
second compression mechanism (72) each including a compression
chamber (85, 95), in which each of the first compression mechanism
(71) and the second compression mechanism (72) sucks low-pressure
refrigerant into the compression chamber (85, 95), and compresses
the low-pressure refrigerant to a high pressure level. The
refrigerant circuit (5) includes an enthalpy reducing unit (20) for
reducing an enthalpy of refrigerant flowing from the radiator to
the evaporator by generating first intermediate-pressure gas
refrigerant and second intermediate-pressure gas refrigerant having
a pressure lower than that of the first intermediate-pressure gas
refrigerant, a first injection path (35) for supplying the first
intermediate-pressure gas refrigerant generated in the enthalpy
reducing unit (20) to the compression chamber (85) of the first
compression mechanism (71) in the middle of a compression process,
and a second injection path (45) for supplying the second
intermediate-pressure gas refrigerant generated in the enthalpy
reducing unit (20) to the compression chamber (95) of the second
compression mechanism (72) in the middle of a compression
process.
[0015] Each of second and third aspects of the invention is
intended for a refrigerating apparatus including a refrigerant
circuit (5) including a radiator and an evaporator and performing a
refrigeration cycle, and a first compression mechanism (71) and a
second compression mechanism (72) each including a compression
chamber (85, 95), in which the first compression mechanism (71)
sucks low-pressure refrigerant into the compression chamber (85)
and compresses the low-pressure refrigerant, and the second
compression mechanism (72) sucks the refrigerant discharged from
the first compression mechanism (71) into the compression chamber
(95) and compresses the refrigerant.
[0016] In the second aspect of the invention, the refrigerant
circuit (5) includes an enthalpy reducing unit (20) for reducing an
enthalpy of refrigerant flowing from the radiator to the evaporator
by generating first intermediate-pressure gas refrigerant and
second intermediate-pressure gas refrigerant having a pressure
lower than that of the first intermediate-pressure gas refrigerant,
a first injection path (35) for supplying the first
intermediate-pressure gas refrigerant generated in the enthalpy
reducing unit (20) to the compression chamber (85) of the first
compression mechanism (71) in the middle of a compression process,
and a second injection path (45) for supplying the second
intermediate-pressure gas refrigerant generated in the enthalpy
reducing unit (20) to the compression chamber (95) of the second
compression mechanism (72) in the middle of a compression process,
or to an inlet side of the second compression mechanism (72).
[0017] In the third aspect of the invention, the refrigerant
circuit (5) includes an enthalpy reducing unit (20) for reducing an
enthalpy of refrigerant flowing from the radiator to the evaporator
by generating first intermediate-pressure gas refrigerant and
second intermediate-pressure gas refrigerant having a pressure
lower than that of the first intermediate-pressure gas refrigerant,
a first injection path (35) for supplying the first
intermediate-pressure gas refrigerant generated in the enthalpy
reducing unit (20) to an inlet side of the second compression
mechanism (72), and a second injection path (45) for supplying the
second intermediate-pressure gas refrigerant generated in the
enthalpy reducing unit (20) to the compression chamber (95) of the
second compression mechanism (72) in the middle of a compression
process.
[0018] In the refrigerant circuit (5) of the first aspect of the
invention, refrigerant circulates to perform a single-stage
compression refrigeration cycle. In the refrigerant circuit (5),
refrigerant discharged from the compression mechanisms (71, 72)
dissipates heat in the radiator. Then, such refrigerant is
evaporated by absorbing heat in the evaporator, and is sucked into
the compression mechanisms (71, 72). On the other hand, in the
refrigerant circuit (5) of each of the second and third aspects of
the invention, refrigerant circulates to perform a two-stage
compression refrigeration cycle. In the refrigerant circuit (5),
refrigerant discharged from the second compression mechanism (72)
dissipates heat in the radiator. Then, such refrigerant is
evaporated by absorbing heat in the evaporator, and is sucked into
the first compression mechanism (71). In the refrigerant circuit
(5) of each of the first to third aspects of the invention, after
refrigerant dissipates heat in the radiator, and its enthalpy is
reduced in the enthalpy reducing unit (20), such refrigerant is
supplied to the evaporator.
[0019] In the enthalpy reducing unit (20) of each of the first to
third aspects of the invention, the first and second
intermediate-pressure gas refrigerants with different pressures are
generated. The enthalpy reducing unit (20) reduces the enthalpy of
refrigerant flowing from the radiator to the evaporator in the
course of generating the two types of intermediate-pressure gas
refrigerant. The second intermediate-pressure gas refrigerant has
the pressure lower than that of the first intermediate-pressure gas
refrigerant, and therefore has a temperature lower than that of the
first intermediate-pressure gas refrigerant. Thus, the enthalpy of
refrigerant sent from the enthalpy reducing unit (20) to the
evaporator is reduced as compared to a case where only the first
intermediate-pressure gas refrigerant is generated in the enthalpy
reducing unit (20).
[0020] In the refrigerant circuit (5) of the first aspect of the
invention, low-pressure refrigerant is sucked into the compression
mechanisms (71, 72). The first intermediate-pressure gas
refrigerant is injected to the compression chamber (85) of the
first compression mechanism (71) in the middle of the compression
process through the first injection path (35). The first
compression mechanism (71) compresses the low-pressure refrigerant
and the first intermediate-pressure gas refrigerant which flow into
the compression chamber (85), and discharges the compressed
high-pressure refrigerant from the compression chamber (85).
Meanwhile, the second intermediate-pressure gas refrigerant is
injected to the compression chamber (95) of the second compression
mechanism (72) in the middle of the compression process through the
second injection path (45). The second compression mechanism (72)
compresses the low-pressure refrigerant and the second
intermediate-pressure gas refrigerant which flow into the
compression chamber (95), and discharges the compressed
high-pressure refrigerant from the compression chamber (95).
[0021] In the refrigerant circuit (5) of the second aspect of the
invention, refrigerant is compressed in the first compression
mechanism (71), and then is further compressed in the second
compression mechanism (72). The first intermediate-pressure gas
refrigerant is injected to the compression chamber (85) of the
first compression mechanism (71) in the middle of the compression
process through the first injection path (35). The first
compression mechanism (71) compresses the low-pressure refrigerant
and the first intermediate-pressure gas refrigerant which flow into
the compression chamber (85), and discharges the compressed
refrigerant from the compression chamber (85). If the second
intermediate-pressure gas refrigerant is injected to the
compression chamber (95) of the second compression mechanism (72)
in the middle of the compression process through the second
injection path (45), the second compression mechanism (72)
compresses the refrigerant discharged from the first compression
mechanism (71) and sucked into the compression chamber (95), and
the second intermediate-pressure gas refrigerant injected to the
compression chamber (95) through the second injection path (45),
and discharges the compressed high-pressure refrigerant from the
compression chamber (95). On the other hand, if the second
intermediate-pressure gas refrigerant is injected to the inlet side
of the second compression mechanism (72) through the second
injection path (45), the second compression mechanism (72) sucks
and compresses the refrigerant discharged from the first
compression mechanism (71), and the second intermediate-pressure
gas refrigerant supplied through the second injection path (45) in
the compression chamber (95), and discharges the compressed
high-pressure refrigerant from the compression chamber (95).
[0022] In the refrigerant circuit (5) of the third aspect of the
invention, refrigerant is compressed in the first compression
mechanism (71), and then is further compressed in the second
compression mechanism (72). The first compression mechanism (71)
compresses the low-pressure refrigerant flowing into the
compression chamber (85), and discharges the compressed refrigerant
from the compression chamber (85). The second compression mechanism
(72) sucks the refrigerant discharged from the first compression
mechanism (71), and the first intermediate-pressure gas refrigerant
supplied through the first injection path (35) into the compression
chamber (95). In addition, the second intermediate-pressure gas
refrigerant is injected to the compression chamber (95) of the
second compression mechanism (72) in the middle of the compression
process through the second injection path (45). The second
compression mechanism (72) compresses the refrigerant sucked into
the compression chamber (95), and the second intermediate-pressure
gas refrigerant injected to the compression chamber (95) through
the second injection path (45), and discharges the compressed
high-pressure refrigerant from the compression chamber (95).
[0023] A fourth aspect of the invention is intended for the
refrigerating apparatus of any one of the first to third aspects of
the invention, in which, in the refrigerant circuit (5), a portion
of the refrigerant circuit (5) from an outlet of the radiator to an
inlet of the evaporator forms a main path (7); and the enthalpy
reducing unit (20) includes a branched path (21) which is connected
to the main path (7) and into which a part of refrigerant flowing
through the main path (7) flows, an expansion mechanism (22) for
expanding the refrigerant flowing into the branched path (21) to
generate first intermediate-pressure refrigerant and second
intermediate-pressure refrigerant having a pressure lower than that
of the first intermediate-pressure refrigerant, a first heat
exchanger (30) which is connected to the main path (7) downstream
the radiator to exchange heat between the refrigerant flowing
through the main path (7) and the first intermediate-pressure
refrigerant, which cools the refrigerant flowing through the main
path (7), and which generates the first intermediate-pressure gas
refrigerant by evaporating the first intermediate-pressure
refrigerant, and a second heat exchanger (40) which is connected to
the main path (7) between the first heat exchanger (30) and the
evaporator to exchange heat between the refrigerant flowing through
the main path (7) and the second intermediate-pressure refrigerant,
which cools the refrigerant flowing through the main path (7), and
which generates the second intermediate-pressure gas refrigerant by
evaporating the second intermediate-pressure refrigerant.
[0024] In the fourth aspect of the invention, the branched path
(21), the expansion mechanism (22), the first heat exchanger (30),
and the second heat exchanger (40) are provided in the enthalpy
reducing unit (20). A part of high-pressure refrigerant flowing out
from the radiator to the main path (7) flows into the branched path
(21). The high-pressure refrigerant flowing into the branched path
(21) is expanded by the expansion mechanism (22). A part of such
refrigerant is changed into the first intermediate-pressure
refrigerant, and the remaining refrigerant is changed into the
second intermediate-pressure refrigerant. The second
intermediate-pressure refrigerant has the pressure and temperature
lower than those of the first intermediate-pressure
refrigerant.
[0025] In the fourth aspect of the invention, in the first heat
exchanger (30), heat is exchanged between the first
intermediate-pressure refrigerant and the high-pressure refrigerant
flowing out from the radiator. In the first heat exchanger (30),
the high-pressure refrigerant is cooled by the first
intermediate-pressure refrigerant, and the enthalpy of the
high-pressure refrigerant is reduced. Meanwhile, the first
intermediate-pressure refrigerant is evaporated by absorbing heat
from the high-pressure refrigerant, thereby generating the first
intermediate-pressure gas refrigerant. The first
intermediate-pressure gas refrigerant generated in the first heat
exchanger (30) flows into the first injection path (35).
[0026] Further, in the fourth aspect of the invention, in the
second heat exchanger (40), heat is exchanged between the second
intermediate-pressure refrigerant and the high-pressure refrigerant
flowing out from the first heat exchanger (30). In the second heat
exchanger (40), the high-pressure refrigerant is cooled by the
second intermediate-pressure refrigerant, and the enthalpy of the
high-pressure refrigerant is reduced. Meanwhile, the second
intermediate-pressure refrigerant is evaporated by absorbing heat
from the high-pressure refrigerant, thereby generating the second
intermediate-pressure gas refrigerant. The second
intermediate-pressure gas refrigerant generated in the second heat
exchanger (40) flows into the second injection path (45).
[0027] A fifth aspect of the invention is intended for the
refrigerating apparatus of the fourth aspect of the invention, in
which the branched path (21) of the enthalpy reducing unit (20)
includes a first branched pipe (33) which is connected to the main
path (7) between the radiator and the first heat exchanger (30),
and which supplies refrigerant flowing from the main path (7) to
the first heat exchanger (30), and a second branched pipe (43)
which is connected to the main path (7) between the first heat
exchanger (30) and the second heat exchanger (40), and which
supplies the refrigerant flowing from the main path (7) to the
second heat exchanger (40); and the expansion mechanism (22) of the
enthalpy reducing unit (20) includes a first expansion valve (34)
which is provided in the first branched pipe (33), and which
generates the first intermediate-pressure refrigerant by expanding
refrigerant flowing into the first branched pipe (33), and a second
expansion valve (44) which is provided in the second branched pipe
(43), and which generates the second intermediate-pressure
refrigerant by expanding refrigerant flowing into the second
branched pipe (43).
[0028] In the fifth aspect of the invention, the branched path (21)
includes the first branched pipe (33) and the second branched pipe
(43), and the expansion mechanism (22) includes the first expansion
valve (34) and the second expansion valve (44). A part of
high-pressure refrigerant flowing from the radiator to the first
heat exchanger (30) through the main path (7) flows into the first
branched pipe (33). The high-pressure refrigerant flowing into the
first branched pipe (33) is expanded into the first
intermediate-pressure refrigerant when passing through the first
expansion valve (34), and then is supplied to the first heat
exchanger (30). In the first heat exchanger (30), the supplied
first intermediate-pressure refrigerant is evaporated into the
first intermediate-pressure gas refrigerant. Meanwhile, a part of
high-pressure refrigerant flowing from the first heat exchanger
(30) to the second heat exchanger (40) through the main path (7)
(i.e., high-pressure refrigerant cooled in the first heat exchanger
(30)) flows into the second branched pipe (43). The high-pressure
refrigerant flowing into the second branched pipe (43) is expanded
into the second intermediate-pressure refrigerant when passing
through the second expansion valve (44), and then is supplied to
the second heat exchanger (40). In the second heat exchanger (40),
the supplied second intermediate-pressure refrigerant is evaporated
into the second intermediate-pressure gas refrigerant.
[0029] A sixth aspect of the invention is intended for the
refrigerating apparatus of the fourth aspect of the invention, in
which the branched path (21) of the enthalpy reducing unit (20)
includes a first branched pipe (33) which is connected to the main
path (7) between the radiator and the first heat exchanger (30),
and which supplies refrigerant flowing from the main path (7) to
the first heat exchanger (30), and a second branched pipe (43)
which is connected to the first branched pipe (33), and which
supplies refrigerant flowing from the first branched pipe (33) to
the second heat exchanger (40); and the expansion mechanism (22) of
the enthalpy reducing unit (20) includes a first expansion valve
(34) which is provided in the first branched pipe (33), and which
generates the first intermediate-pressure refrigerant by expanding
refrigerant flowing into the first branched pipe (33), and a second
expansion valve (44) which is provided in the second branched pipe
(43), and which generates the second intermediate-pressure
refrigerant by expanding refrigerant flowing into the second
branched pipe (43).
[0030] In the sixth aspect of the invention, the branched path (21)
includes the first branched pipe (33) and the second branched pipe
(43), and the expansion mechanism (22) includes the first expansion
valve (34) and the second expansion valve (44). A part of
high-pressure refrigerant flowing from the radiator to the first
heat exchanger (30) through the main path (7) flows into the first
branched pipe (33). A part of the refrigerant flowing into the
first branched pipe (33) is supplied to the first heat exchanger
(30). The remaining refrigerant flows into the second branched pipe
(43), and is supplied to the second heat exchanger (40). The
refrigerant supplied to the first heat exchanger (30) through the
first branched pipe (33) is expanded into the first
intermediate-pressure refrigerant when passing through the first
expansion valve (34), and then is supplied to the first heat
exchanger (30). In the first heat exchanger (30), the supplied
first intermediate-pressure refrigerant is evaporated into the
first intermediate-pressure gas refrigerant. Meanwhile, the
refrigerant supplied to the second heat exchanger (40) through the
second branched pipe (43) is expanded into the second
intermediate-pressure refrigerant when passing through the second
expansion valve (44), and then is supplied to the second heat
exchanger (40). In the second heat exchanger (40), the supplied
second intermediate-pressure refrigerant is evaporated into the
second intermediate-pressure gas refrigerant.
[0031] A seventh aspect of the invention is intended for the
refrigerating apparatus of any one of the first to third aspects of
the invention, in which the enthalpy reducing unit (20) includes a
first expansion valve (37) for expanding high-pressure refrigerant
flowing out from the radiator, a first gas-liquid separator (36)
for separating the refrigerant flowing out from the first expansion
valve (37) in a gas-liquid two-phase state into gas refrigerant and
liquid refrigerant, and supplying the gas refrigerant to the first
injection path (35) as the first intermediate-pressure gas
refrigerant, a second expansion valve (47) for expanding the liquid
refrigerant flowing out from the first gas-liquid separator (36),
and a second gas-liquid separator (46) for separating the
refrigerant flowing out from the second expansion valve (47) in the
gas-liquid two-phase state into gas refrigerant and liquid
refrigerant, supplying the gas refrigerant to the second injection
path (45) as the second intermediate-pressure gas refrigerant, and
supplying the liquid refrigerant to the evaporator.
[0032] In the seventh aspect of the invention, the first expansion
valve (37), the first gas-liquid separator (36), the second
expansion valve (47), and the second gas-liquid separator (46) are
provided in the enthalpy reducing unit (20). In the refrigerant
circuit (5), the first expansion valve (37), the first gas-liquid
separator (36), the second expansion valve (47), and the second
gas-liquid separator (46) are arranged in this order from the
radiator to the evaporator.
[0033] In the seventh aspect of the invention, high-pressure
refrigerant flowing out from the radiator is expanded into the
gas-liquid two-phase state when passing through the first expansion
valve (37). Then, such refrigerant flows into the first gas-liquid
separator (36), and is separated into liquid refrigerant and gas
refrigerant. The gas refrigerant in the first gas-liquid separator
(36) flows into the first injection path (35) as the first
intermediate-pressure gas refrigerant. The liquid refrigerant in
the first gas-liquid separator (36) is in a saturated state, and
the enthalpy of the liquid refrigerant is lower than that of the
refrigerant which is sent to the first gas-liquid separator (36)
through the first expansion valve (37) in the gas-liquid two-phase
state.
[0034] In the seventh aspect of the invention, the liquid
refrigerant in the first gas-liquid separator (36) is expanded into
the gas-liquid two-phase state when passing through the second
expansion valve (47). Then, such refrigerant flows into the second
gas-liquid separator (46), and is separated into liquid refrigerant
and gas refrigerant. The gas refrigerant in the second gas-liquid
separator (46) flows into the second injection path (45) as the
second intermediate-pressure gas refrigerant. The liquid
refrigerant in the second gas-liquid separator (46) is in the
saturated state, and the enthalpy of the liquid refrigerant is
lower than that of the refrigerant which is sent to the second
gas-liquid separator (46) through the second expansion valve (47)
in the gas-liquid two-phase state. The liquid refrigerant in the
second gas-liquid separator (46) is supplied to the evaporator.
[0035] An eighth aspect of the invention is intended for the
refrigerating apparatus of any one of the first to seventh aspects
of the invention, in which the first compression mechanism (71) and
the second compression mechanism (72) are provided in a single
compressor (50), and the compressor (50) includes a single drive
shaft (65) engaged with both of the first compression mechanism
(71) and the second compression mechanism (72).
[0036] In the eighth aspect of the invention, both of the first
compression mechanism (71) and the second compression mechanism
(72) are driven by the single drive shaft (65).
[0037] A ninth aspect of the invention is intended for the
refrigerating apparatus of any one of the first to seventh aspects
of the invention, in which the first compression mechanism (71) is
provided in a first compressor (50a), and the second compression
mechanism (72) is provided in a second compressor (50b), and the
first compressor (50a) includes a drive shaft (65a) engaged with
the first compression mechanism (71), and the second compression
mechanism (72) includes a drive shaft (65b) engaged with the second
compression mechanism (72).
[0038] In the ninth aspect of the invention, the first compression
mechanism (71) is driven by the drive shaft (65a), and the second
compression mechanism (72) is driven by the drive shaft (65b).
Advantages of the Invention
[0039] The first intermediate-pressure gas refrigerant generated in
the enthalpy reducing unit (20) of the present invention is higher
in the pressure and density than the second intermediate-pressure
gas refrigerant. In the compressor (50) of the present invention,
the second intermediate-pressure gas refrigerant is supplied to the
second compression mechanism (72), and the first
intermediate-pressure gas refrigerant having the pressure and
density higher than those of the second intermediate-pressure gas
refrigerant is supplied to the first compression mechanism (71).
Thus, according to the present invention, a mass flow rate of
refrigerant discharged from the compressor (50) can be increased as
compared to a case where only the second intermediate-pressure gas
refrigerant is supplied to the compression mechanism (71, 72). In
the present invention, since the first and second
intermediate-pressure gas refrigerants are injected to the
compression chambers (85, 95) in the middle of the compression
process, a mass flow rate of low-pressure refrigerant sucked into
the compressor (50) from the evaporator is not increased, and only
the mass flow rate of refrigerant discharged from the compressor
(50) to the radiator is increased. Thus, according to the present
invention, while reducing an increase in energy required for
driving the compressor (50), the mass flow rate of refrigerant
discharged from the compressor (50) can be increased, and an amount
of heat released from refrigerant to a target object such as air in
the radiator (i.e., a heat dissipation amount of refrigerant) can
be increased.
[0040] In the present invention, not only the first
intermediate-pressure gas refrigerant but also the second
intermediate-pressure gas refrigerant having the pressure and
temperature lower than those of the first intermediate-pressure gas
refrigerant are generated in the enthalpy reducing unit (20). Thus,
according to the present invention, the enthalpy of refrigerant
sent from the enthalpy reducing unit (20) to the evaporator is
reduced as compared to the case where only the first
intermediate-pressure gas refrigerant is generated in the enthalpy
reducing unit (20). Consequently, an amount of heat absorbed from
the target object such as air by refrigerant in the evaporator
(i.e., a heat absorption amount of refrigerant) can be
increased.
[0041] As described above, according to the present invention, an
increase in mass flow rate of refrigerant in the radiator results
in an increase in heat dissipation amount of refrigerant in the
radiator. Further, a reduction in enthalpy of refrigerant flowing
into the evaporator results in an increase in heat absorption
amount of refrigerant in the evaporator. Thus, according to the
present invention, both of the heat dissipation amount of
refrigerant in the radiator and the heat absorption amount of
refrigerant in the evaporator can be ensured.
[0042] In a refrigerant circuit in which a multiple-stage
compression refrigeration cycle is performed, intermediate-pressure
gas refrigerant is supplied to each section between compressors.
That is, in, e.g., a refrigerant circuit in which a three-stage
compression refrigeration cycle is performed, intermediate-pressure
gas refrigerant is supplied between a compressor at a first stage
and a compressor at a second stage, and between the compressor at
the second stage and a compressor at a third stage.
[0043] On the other hand, in the refrigerant circuit of the present
invention, the first and second intermediate-pressure gas
refrigerants with different pressures are generated in the enthalpy
reducing unit (20). Thus, in the refrigerant circuit of the present
invention, employment of a "configuration in which three
compression mechanisms are used to perform a three-stage
compression refrigeration cycle, the second intermediate-pressure
gas refrigerant is supplied between a compression mechanism at a
first stage and a compression mechanism at a second stage, and the
first intermediate-pressure gas refrigerant is supplied between the
compression mechanism at the second stage and a compression
mechanism at a third stage" is technically allowed.
[0044] However, if such a configuration is employed in the
refrigerant circuit of the present invention, there are problems
that operational efficiency of the refrigerating apparatus cannot
be sufficiently improved, and a manufacturing cost of the
refrigerating apparatus is increased. Such problems will be
described below.
[0045] Typically, a three-stage compression refrigeration cycle is
performed when only a low COP (coefficient of performance) can be
obtained in a two-stage compression refrigerant cycle or a
single-stage compression refrigeration cycle due to a large
difference between low and high pressure levels of the
refrigeration cycle.
[0046] On the other hand, in the present invention, the
"configuration in which the enthalpy reducing unit (20) configured
to reduce the enthalpy of refrigerant flowing toward the evaporator
generates the first and second intermediate-pressure gas
refrigerants with different pressures" is employed in order to
accomplish the objective which is to "ensure both of the heat
dissipation amount of refrigerant in the radiator and the heat
absorption amount of refrigerant in the evaporator." That is, in
order to accomplish the objective of the present invention, it may
be required that the "configuration in which the enthalpy reducing
unit (20) generates the first and second intermediate-pressure gas
refrigerants" is employed even when the "difference between the low
and high pressure levels of the refrigeration cycle is not so
large, and a sufficiently high COP can be obtained in the two-stage
compression refrigeration cycle or the single-stage compression
refrigeration cycle."
[0047] Since the compression mechanism for compressing refrigerant
typically includes a plurality of members, a mechanical loss such
as a friction loss between the members is caused in the compression
mechanism. Thus, the greater number of compression mechanisms
results in a greater overall mechanical loss caused in each of the
compression mechanisms. In addition, the greater number of
compression mechanisms provided in the refrigerating apparatus
results in a higher manufacturing cost of the refrigerating
apparatus. For such reasons, even when the "difference between the
low and high pressure levels of the refrigeration cycle is not so
large, and the sufficiently high COP can be obtained in the
two-stage compression refrigeration cycle or the single-stage
compression refrigeration cycle," if the "configuration in which
the three compression mechanisms are used to perform the
three-stage compression refrigeration cycle" is employed, there are
problems that an increase in mechanical loss in the compression
mechanism causes degradation of the operational efficiency of the
refrigerating apparatus, and an increase in the number of
compression mechanisms causes an increase in manufacturing cost of
the refrigerating apparatus.
[0048] On the other hand, in the first aspect of the invention, in
the refrigerant circuit (5) in which the single-stage compression
refrigeration cycle is performed, the first and second
intermediate-pressure gas refrigerants generated in the enthalpy
reducing unit (20) are sucked into the compression mechanisms (71,
72). In addition, in each of the second and third aspects of the
invention, in the refrigerant circuit (5) in which the two-stage
compression refrigeration cycle, the first and second
intermediate-pressure gas refrigerants generated in the enthalpy
reducing unit (20) are sucked into the compression mechanisms (71,
72).
[0049] As described above, according to the present invention, even
in the refrigerant circuit (5) in which the single-stage
compression refrigeration cycle or the two-stage compression
refrigeration cycle is performed, the first and second
intermediate-pressure gas refrigerants generated in the enthalpy
reducing unit (20) can be sucked into the compression mechanisms
(71, 72). Thus, according to the present invention, a situation can
be avoided, in which the "three-stage compression refrigeration
cycle is performed only for the purpose of processing the first and
second intermediate-pressure gas refrigerants generated in the
enthalpy reducing unit (20) even through the difference between the
low and high pressure levels of the refrigeration cycle is not so
large." Consequently, the problems such as the increase in
mechanical loss and the increase in manufacturing cost due to the
increase in the number of compression mechanisms can be solved.
[0050] In the fourth aspect of the invention, the first heat
exchanger (30) and the second heat exchanger (40) are provided in
the enthalpy reducing unit (20). In the first heat exchanger (30),
high-pressure refrigerant flowing out from the radiator is cooled
by the first intermediate-pressure refrigerant. In the second heat
exchanger (40), the high-pressure refrigerant cooled in the first
heat exchanger (30) is further cooled by the second
intermediate-pressure refrigerant. Thus, according to the present
invention, the reduction in enthalpy of refrigerant sent from the
radiator to the evaporator can be ensured in the course of
generating the first and second intermediate-pressure gas
refrigerants.
[0051] In the seventh aspect of the invention, the first gas-liquid
separator (36) and the second gas-liquid separator (46) are
provided in the enthalpy reducing unit (20). The first gas-liquid
separator (36) sends only saturated liquid refrigerant having an
enthalpy lower than that of refrigerant which is supplied to the
first gas-liquid separator (36) through the first expansion valve
(37) in the gas-liquid two-phase state, to the second gas-liquid
separator (46). In addition, the second gas-liquid separator (46)
sends only saturated liquid refrigerant having an enthalpy lower
than that of refrigerant which is supplied to the second gas-liquid
separator (46) through the second expansion valve (47) in the
gas-liquid two-phase state, to the evaporator. Thus, according to
the present invention, the reduction in enthalpy of refrigerant
sent from the radiator to the evaporator can be ensured in the
course of generating the first and second intermediate-pressure gas
refrigerants.
BRIEF DESCRIPTION OF THE DRAWINGS
[0052] FIG. 1 is a refrigerant circuit diagram illustrating a
configuration of an air conditioner of a first embodiment.
[0053] FIG. 2 is a longitudinal sectional view of a compressor of
the first embodiment.
[0054] FIG. 3 are cross-sectional views of a main section of the
compressor of the first embodiment. FIG. 3(A) is a cross-sectional
view of a first compression mechanism, and FIG. 3(B) is a
cross-sectional view of a second compression mechanism.
[0055] FIG. 4 is a Mollier diagram (pressure-enthalpy diagram)
illustrating a refrigeration cycle performed in a refrigerant
circuit of the first embodiment.
[0056] FIG. 5 is a refrigerant circuit diagram illustrating a
configuration of an air conditioner of a second embodiment.
[0057] FIG. 6 is a Mollier diagram (pressure-enthalpy diagram)
illustrating a refrigeration cycle performed in a refrigerant
circuit of the second embodiment.
[0058] FIG. 7 is a refrigerant circuit diagram illustrating a
configuration of an air conditioner of a first variation of the
second embodiment.
[0059] FIG. 8 is a refrigerant circuit diagram illustrating a
configuration of an air conditioner of a second variation of the
second embodiment.
[0060] FIG. 9 is a Mollier diagram (pressure-enthalpy diagram)
illustrating a refrigeration cycle performed in a refrigerant
circuit of the second variation of the second embodiment.
[0061] FIG. 10 is a refrigerant circuit diagram illustrating a
configuration of an air conditioner of a third embodiment.
[0062] FIG. 11 is a Mollier diagram (pressure-enthalpy diagram)
illustrating a refrigeration cycle performed in a refrigerant
circuit of the third embodiment.
[0063] FIG. 12 is a schematic perspective view illustrating a
configuration of a heat exchange member of a first variation of
other embodiment.
[0064] FIG. 13 is a schematic side view illustrating the
configuration of the heat exchange member of the first variation of
the other embodiment.
[0065] FIG. 14 is a refrigerant circuit diagram illustrating a
configuration of an air conditioner of a second variation of the
other embodiment.
[0066] FIG. 15 is a refrigerant circuit diagram illustrating a
configuration of an air conditioner of a third variation of the
other embodiment.
[0067] FIG. 16 is a Mollier diagram (pressure-enthalpy diagram)
illustrating a refrigeration cycle performed in a refrigerant
circuit of the third variation of the other embodiment.
[0068] FIG. 17 is a refrigerant circuit diagram illustrating a
configuration of an air conditioner of a fourth variation of the
other embodiment.
[0069] FIG. 18 is a Mollier diagram (pressure-enthalpy diagram)
illustrating a refrigeration cycle performed in a refrigerant
circuit of the fourth variation of the other embodiment.
[0070] FIG. 19 is a refrigerant circuit diagram illustrating a
configuration of an air conditioner of the fourth variation of the
other embodiment.
[0071] FIG. 20 is a refrigerant circuit diagram illustrating a
configuration of an air conditioner of a fifth variation of the
other embodiment.
[0072] FIG. 21 is another refrigerant circuit diagram illustrating
the configuration of the air conditioner of the fifth variation of
the other embodiment.
[0073] FIG. 22 is another refrigerant circuit diagram illustrating
the configuration of the air conditioner of the fifth variation of
the other embodiment.
DESCRIPTION OF EMBODIMENTS
[0074] Embodiments of the present invention will be described below
in detail with reference to the drawings.
First Embodiment of the Invention
[0075] A first embodiment of the present invention will be
described. The present embodiment is intended for an air
conditioner (1) configured by a refrigerating apparatus.
[0076] <Configuration of Refrigerant Circuit>
[0077] The air conditioner (1) of the present embodiment includes a
refrigerant circuit (5). The refrigerant circuit (5) is a closed
circuit filled with refrigerant, and refrigerant circulates to
perform a vapor compression refrigeration cycle. The refrigerant
circuit (5) is filled with zeotropic refrigerant mixture containing
2,3,3,3-tetrafluoro-1-propene (HFO-1234yf) which is a high-boiling
component and HFC-32 (difluoromethane) which is a low-boiling
component.
[0078] As illustrated in FIG. 1, the refrigerant circuit (5)
includes a compressor (50), a four-way valve (11), and an outdoor
heat exchanger (12), a bridge circuit (15), and an indoor heat
exchanger (14). A discharge pipe (52) of the compressor (50) is
connected to a first port of the four-way valve (11), and suction
pipes (53, 54) of the compressor (50) are connected to a second
port of the four-way valve (11). A gas inlet/outlet end of the
outdoor heat exchanger (12) is connected to a third port of the
four-way valve (11), and a liquid inlet/outlet end of the outdoor
heat exchanger (12) is connected to the bridge circuit (15). A gas
inlet/outlet end of the indoor heat exchanger (14) is connected to
a fourth port of the four-way valve (11), and a liquid inlet/outlet
end of the indoor heat exchanger (14) is connected to the bridge
circuit (15).
[0079] The compressor (50) is a hermetic rotary compressor. In the
compressor (50), a main body (70) including a first compression
mechanism (71) and a second compression mechanism (72), an electric
motor (60) for driving the main body (70), and a drive shaft (65)
connecting between the main body (70) and the electric motor (60)
are accommodated in a casing (51). The compressor (50) will be
described in detail later.
[0080] The four-way valve (11) is switchable between a first state
(state indicated by a solid line in FIG. 1) in which the first port
is communicated with the third port, and the second port is
communicated with the fourth port; and a second state (state
indicated by a dashed line in FIG. 1) in which the first port is
communicated with the fourth port, and the second port is
communicated with the third port. In the outdoor heat exchanger
(12), heat is exchanged between outdoor air and refrigerant. In the
indoor heat exchanger (14), heat is exchanged between room air and
refrigerant.
[0081] The bridge circuit (15) includes four check valves (16-19).
In the bridge circuit (15), an outlet side of the first check valve
(16) and an outlet side of the second check valve (17) are
connected together, and an inlet side of the second check valve
(17) and an outlet side of the third check valve (18) are connected
together. In addition, an inlet side of the third check valve (18)
and an inlet side of the fourth check valve (19) are connected
together, and an outlet side of the fourth check valve (19) and an
inlet side of the first check valve (16) are connected together.
Further, in the bridge circuit (15), the liquid inlet/outlet end of
the outdoor heat exchanger (12) is connected between the fourth
check valve (19) and the first check valve (16), and the liquid
inlet/outlet end of the indoor heat exchanger (14) is connected
between the second check valve (17) and the third check valve
(18).
[0082] A one-way circulation pipe line (6) is provided in the
refrigerant circuit (5). An inlet end of the one-way circulation
pipe line (6) is connected to the bridge circuit (15) between the
first check valve (16) and the second check valve (17), and an
outlet end of the one-way circulation pipe line (6) is connected to
the bridge circuit (15) between the third check valve (18) and the
fourth check valve (19). In the one-way circulation pipe line (6),
refrigerant constantly flows from the inlet end toward the outlet
end. In the refrigerant circuit (5), a main path (7) is formed by
the pipe connecting between the liquid inlet/outlet end of the
outdoor heat exchanger (12) and the bridge circuit (15), the pipe
connecting between the liquid inlet/outlet end of the indoor heat
exchanger (14) and the bridge circuit (15), the bridge circuit
(15), and the one-way circulation pipe line (6).
[0083] A first heat exchanger (30), a second heat exchanger (40),
and a main expansion valve (13) are connected to the one-way
circulation pipe line (6) in this order from the inlet end toward
the outlet end. The main expansion valve (13) is a so-called
"electronic expansion valve." Each of the first heat exchanger (30)
and the second heat exchanger (40) includes a high-pressure flow
path (31, 41) and an intermediate-pressure flow path (32, 42), and
is configured so that heat is exchanged between refrigerant flowing
through the high-pressure flow path (31, 41) and refrigerant
flowing through the intermediate-pressure flow path (32, 42). The
high-pressure flow paths (31, 41) of the first heat exchanger (30)
and the second heat exchanger (40) are connected to the one-way
circulation pipe line (6).
[0084] A first branched pipe (33) and a first injection pipe (35)
are connected to the intermediate-pressure flow path (32) of the
first heat exchanger (30). One end of the first branched pipe (33)
is connected to the one-way circulation pipe line (6) upstream the
first heat exchanger (30), and the other end of the first branched
pipe (33) is connected to an inlet end of the intermediate-pressure
flow path (32) of the first heat exchanger (30). A first expansion
valve (34) which is a so-called "electronic expansion valve" is
provided in the first branched pipe (33). The first expansion valve
(34) expands high-pressure refrigerant flowing into the first
branched pipe (33) from the one-way circulation pipe line (6) to
generate first intermediate-pressure refrigerant. One end of the
first injection pipe (35) is connected to an outlet end of the
intermediate-pressure flow path (32) of the first heat exchanger
(30), and the other end of the first injection pipe (35) is
connected to the first compression mechanism (71) of the compressor
(50).
[0085] A second branched pipe (43) and a second injection pipe (45)
are connected to the intermediate-pressure flow path (42) of the
second heat exchanger (40). One end of the second branched pipe
(43) is connected to the one-way circulation pipe line (6) between
the first heat exchanger (30) and the second heat exchanger (40),
and the other end of the second branched pipe (43) is connected to
an inlet side of the intermediate-pressure flow path (42) of the
second heat exchanger (40). A second expansion valve (44) which is
a so-called "electronic expansion valve" is provided in the second
branched pipe (43). The second expansion valve (44) expands
high-pressure refrigerant flowing into the second branched pipe
(43) from the one-way circulation pipe line (6) to generate second
intermediate-pressure refrigerant. One end of the second injection
pipe (45) is connected to an outlet side of the
intermediate-pressure flow path (42) of the second heat exchanger
(40), and the other end of the second injection pipe (45) is
connected to the second compression mechanism (72) of the
compressor (50).
[0086] In the refrigerant circuit (5) of the present embodiment,
the first heat exchanger (30), the first branched pipe (33), the
first expansion valve (34), the second heat exchanger (40), the
second branched pipe (43), and the second expansion valve (44) form
an enthalpy reducing unit (20) configured to reduce an enthalpy of
refrigerant flowing through the one-way circulation pipe line (6).
In addition, in the refrigerant circuit (5), the first branched
pipe (33) and the second branched pipe (43) form a branched path
(21), and the first expansion valve (34) and the second expansion
valve (44) form an expansion mechanism (22). Further, in the
refrigerant circuit (5), the first injection pipe (35) forms a
first injection path, and the second injection pipe (45) forms a
second injection path.
[0087] <Configuration of Compressor>
[0088] As illustrated in FIG. 2, the compressor (50) includes the
casing (51), the main body (70), the electric motor (60), and the
drive shaft (65). The casing (51) is formed in an elongated hollow
cylindrical shape which is closed at both ends. The electric motor
(60) is arranged above the main body (70) in the casing (51). In a
top portion of the casing (51), the discharge pipe (52) is provided
so as to penetrate the casing (51).
[0089] The electric motor (60) includes a stator (61) and a rotor
(62). The stator (61) is fixed to a portion of a body section of
the casing (51) closer to the top. The rotor (62) is arranged
inside the stator (61).
[0090] The drive shaft (65) includes a main shaft portion (68), a
first eccentric portion (66), and a second eccentric portion (67).
A portion of the main shaft portion (68) closer to its upper end is
connected to the rotor (62). The first eccentric portion (66) and
the second eccentric portion (67) are formed closer to a lower end
of the main shaft portion (68). The first eccentric portion (66) is
arranged above the second eccentric portion (67). An outer diameter
of each of the first eccentric portion (66) and the second
eccentric portion (67) is larger than an outer diameter of the main
shaft portion (68), and each of the first eccentric portion (66)
and the second eccentric portion (67) is eccentric to the center of
the main shaft portion (68). An eccentric direction of one of the
first eccentric portion (66) and the second eccentric portion (67)
relative to the center of the main shaft portion (68) is opposite
to an eccentric direction of the remaining one of the first
eccentric portion (66) and the second eccentric portion (67). An
oil supply path (69) upwardly extending from the lower end of the
main shaft portion (68) is formed in the main shaft portion
(68).
[0091] The main body (70) includes a front heat (73), a first
cylinder (81), a middle plate (75), a second cylinder (91), and a
rear head (74), and forms a swing piston type rotary fluid machine.
The rear head (74), the second cylinder (91), the middle plate
(75), the first cylinder (81), and the front heat (73) are stacked
in the main body (70) in this order from the bottom to the top, and
are fastened together with bolts which are not shown in the
figure.
[0092] As illustrated in FIGS. 3(A) and 3(B), a first piston (82)
is accommodated in the first cylinder (81), and a second piston
(92) is accommodated in the second cylinder (91). The piston (82,
92) is formed in a slightly-thick cylindrical shape with a low
height. The first eccentric portion (66) is inserted into the first
piston (82), and the second eccentric portion (67) is inserted into
the second piston (92). A flat plate-like blade (83, 93) protruding
from an outer circumferential surface of the piston (82, 92) is
integrally formed with the piston (82, 92). The blade (83)
integrally formed with the first piston (82) is supported by the
first cylinder (81) through a pair of bushes (84). The blade (93)
integrally formed with the second piston (92) is supported by the
second cylinder (91) through a pair of bushes (94).
[0093] In the first cylinder (81) sandwiched between the front heat
(73) and the middle plate (75), a first compression chamber (85) is
formed between an inner circumferential surface of the first
cylinder (81) and an outer circumferential surface of the first
piston (82). The first compression chamber (85) is divided into
low-pressure and high-pressure sides by the blade (83). In the
second cylinder (91) sandwiched between the middle plate (75) and
the rear head (74), a second compression chamber (95) is formed
between an inner circumferential surface of the second cylinder
(91) and an outer circumferential surface of the second piston
(92). The second compression chamber (95) is divided into
low-pressure and high-pressure sides by the blade (93).
[0094] A first suction port (86) is formed in the first cylinder
(81). In addition, a second suction port (96) is formed in the
second cylinder (91). In the cylinder (81, 91), the suction port
(86, 96) penetrates the cylinder (81, 91) in a radial direction.
The suction port (86, 96) opens onto the inner circumferential
surface of the cylinder (81, 91) near the right side of the blade
(83, 93) as viewed in FIGS. 3(A) and 3(B). The suction pipe (53) is
inserted into the first suction port (86), and the suction pipe
(54) is inserted into the second suction port (96). The suction
pipe (53, 54) extends to an outside of the casing (51).
[0095] A first discharge port (87) is formed in the front heat
(73). The first discharge port (87) penetrates the front heat (73).
The first discharge port (87) opens onto a front surface (lower
surface) of the front heat (73) near the left side of the blade
(83) as viewed in FIG. 3(A). A first discharge valve (88)
configured to open/close the first discharge port (87) is provided
in the front heat (73).
[0096] A second discharge port (97) is formed in the rear head
(74). The second discharge port (97) penetrates the rear head (74).
The second discharge port (97) opens onto a front surface (upper
surface) of the rear head (74) near the left side of the blade (93)
as viewed in FIG. 3(B). A second discharge valve (98) configured to
open/close the second discharge port (97) is provided in the rear
head (74).
[0097] A first injection port (89) is formed in the middle plate
(75). One end of the first injection port (89) opens onto an upper
surface of the middle plate (75), and the other end of the first
injection port (89) opens onto an outer surface of the middle plate
(75). The one end of the first injection port (89) opens onto the
upper surface of the middle plate (75) in a portion facing the
first compression chamber (85). The first injection pipe (35) is
inserted into the other end of the first injection port (89).
[0098] A second injection port (99) is formed in the rear head
(74). One end of the second injection port (99) opens onto the
front surface (upper surface) of the rear head (74), and the other
end of the second injection port (99) opens onto an outer surface
of the rear head (74). The one end of the second injection port
(99) opens onto the front surface of the rear head (74) in a
portion facing the second compression chamber (95). The second
injection pipe (45) is injected into the other end of the second
injection port (99).
[0099] In the main body (70) of the compressor (50) of the present
embodiment, the front heat (73), the first cylinder (81), the
middle plate (75), the first piston (82), and the blade (83) form
the first compression mechanism (71) defining the first compression
chamber (85). In addition, in the main body (70), the rear head
(74), the second cylinder (91), the middle plate (75), the second
piston (92), and the blade (93) form the second compression
mechanism (72) defining the second compression chamber (95).
[0100] Operation
[0101] The air conditioner (1) of the present embodiment switches
between cooling and heating operations.
[0102] <Cooling Operation of Air Conditioner>
[0103] A process in the air conditioner (1) during the cooling
operation will be described with reference to FIG. 1. In the
cooling operation, the four-way valve (11) is set to the first
state (state indicated by the solid line in FIG. 1), and degrees of
opening of the first expansion valve (34), the second expansion
valve (44), and the main expansion valve (13) are adjusted as
necessary. When driving the compressor (50) in such a state,
refrigerant circulates in the refrigerant circuit (5) as indicated
by solid arrows in FIG. 1, thereby performing the vapor compression
refrigeration cycle. At this point, the outdoor heat exchanger (12)
is operated as a condenser (i.e., a radiator), and the indoor heat
exchanger (14) is operated as an evaporator.
[0104] Refrigerant discharged from the compressor (50) flows into
the outdoor heat exchanger (12) through the four-way valve (11).
Such refrigerant dissipates heat to outdoor air, and is condensed.
Subsequently, the refrigerant flows into the one-way circulation
pipe line (6) through the first check valve (16) of the bridge
circuit (15).
[0105] A part of the high-pressure refrigerant flowing into the
one-way circulation pipe line (6) flows into the first branched
pipe (33), and the remaining refrigerant flows into the
high-pressure flow path (31) of the first heat exchanger (30). The
high-pressure refrigerant flowing into the first branched pipe (33)
is expanded into first intermediate-pressure refrigerant when
passing through the first expansion valve (34), and then flows into
the intermediate-pressure flow path (32) of the first heat
exchanger (30). In the first heat exchanger (30), the high-pressure
refrigerant flowing through the high-pressure flow path (31) is
cooled, and the first intermediate-pressure refrigerant flowing
through the intermediate-pressure flow path (32) is evaporated into
first intermediate-pressure gas refrigerant. The first
intermediate-pressure gas refrigerant is sent to the compressor
(50) through the first injection pipe (35).
[0106] A part of the high-pressure refrigerant flowing out from the
high-pressure flow path (31) of the first heat exchanger (30) flows
into the second branched pipe (43), and the remaining refrigerant
flows into the high-pressure flow path (41) of the second heat
exchanger (40). The high-pressure refrigerant flowing into the
second branched pipe (43) is expanded into second
intermediate-pressure refrigerant when passing through the second
expansion valve (44), and then flows into the intermediate-pressure
flow path (42) of the second heat exchanger (40). In the second
heat exchanger (40), the high-pressure refrigerant flowing through
the high-pressure flow path (41) is cooled, and the second
intermediate-pressure refrigerant flowing through the
intermediate-pressure flow path (42) is evaporated into second
intermediate-pressure gas refrigerant. The second
intermediate-pressure gas refrigerant is sent to the compressor
(50) through the second injection pipe (45).
[0107] The high-pressure refrigerant flowing out from the
high-pressure flow path (41) of the second heat exchanger (40) is
expanded into low-pressure refrigerant when passing through the
main expansion valve (13). The low-pressure refrigerant flows into
the indoor heat exchanger (14) through the third check valve (18)
of the bridge circuit (15). Such refrigerant absorbs heat from room
air, and is evaporated. Subsequently, the refrigerant is sucked
into the main body (70) of the compressor (50) through the four-way
valve (11). In the indoor heat exchanger (14), the room air is
cooled by exchanging heat with the refrigerant, and the cooled room
air is sent back to a room.
[0108] <Heating Operation of Air Conditioner>
[0109] A process in the air conditioner (1) during the heating
operation will be described with reference to FIG. 1. In the
heating operation, the four-way valve (11) is set to the second
state (state indicated by the dashed line in FIG. 1), and the
degrees of opening of the first expansion valve (34), the second
expansion valve (44), and the main expansion valve (13) are
adjusted as necessary. When driving the compressor (50) in such a
state, refrigerant circulates in the refrigerant circuit (5) as
indicated by dashed arrows in FIG. 1, thereby performing the vapor
compression refrigeration cycle. At this point, in the refrigerant
circuit (5), the indoor heat exchanger (14) is operated as the
condenser (i.e., the radiator), and the outdoor heat exchanger (12)
is operated as the evaporator.
[0110] Refrigerant discharged from the compressor (50) flows into
the indoor heat exchanger (14) through the four-way valve (11).
Such refrigerant dissipates heat to room air, and is condensed.
Subsequently, the refrigerant flows into the one-way circulation
pipe line (6) through the second check valve (17) of the bridge
circuit (15). In the indoor heat exchanger (14), the room air is
heated by exchanging heat with the refrigerant, and the heated room
air is sent back to the room.
[0111] A part of the high-pressure refrigerant flowing into the
one-way circulation pipe line (6) flows into the first branched
pipe (33), and the remaining refrigerant flows into the
high-pressure flow path (31) of the first heat exchanger (30). The
high-pressure refrigerant flowing into the first branched pipe (33)
is expanded into first intermediate-pressure refrigerant when
passing through the first expansion valve (34), and then flows into
the intermediate-pressure flow path (32) of the first heat
exchanger (30). In the first heat exchanger (30), the high-pressure
refrigerant flowing through the high-pressure flow path (31) is
cooled, and the first intermediate-pressure refrigerant flowing
through the intermediate-pressure flow path (32) is evaporated into
first intermediate-pressure gas refrigerant. The first
intermediate-pressure gas refrigerant is sent to the compressor
(50) through the first injection pipe (35).
[0112] A part of the high-pressure refrigerant flowing out from the
high-pressure flow path (31) of the first heat exchanger (30) flows
into the second branched pipe (43), and the remaining refrigerant
flows into the high-pressure flow path (41) of the second heat
exchanger (40). The high-pressure refrigerant flowing into the
second branched pipe (43) is expanded into second
intermediate-pressure refrigerant when passing through the second
expansion valve (44), and then flows into the intermediate-pressure
flow path (32) of the second heat exchanger (40). In the second
heat exchanger (40), the high-pressure refrigerant flowing through
the high-pressure flow path (41) is cooled, and the second
intermediate-pressure refrigerant flowing through the
intermediate-pressure flow path (42) is evaporated into second
intermediate-pressure as refrigerant. The second
intermediate-pressure gas refrigerant is sent to the compressor
(50) through the second injection pipe (45).
[0113] The high-pressure refrigerant flowing out from the
high-pressure flow path (41) of the second heat exchanger (40) is
expanded into low-pressure refrigerant when passing through the
main expansion valve (13). The low-pressure refrigerant flows into
the outdoor heat exchanger (12) through the fourth check valve (19)
of the bridge circuit (15). Such refrigerant absorbs heat from
outdoor air, and is evaporated. Subsequently, the refrigerant is
sucked into the main body (70) of the compressor (50) through the
four-way valve (11).
[0114] <Operation of Compressor>
[0115] An operation of the compressor (50) will be described with
reference to FIGS. 2, 3(A), and 3(B). As described above, the main
body (70) of the compressor (50) sucks low-pressure refrigerant
from either one of the outdoor heat exchanger (12) and the indoor
heat exchanger (14), which is operated as the evaporator. A half of
the low-pressure refrigerant flowing into the compressor (50) is
sucked into the first compression chamber (85) of the first
compression mechanism (71), and the remaining half of the
low-pressure refrigerant is sucked into the second compression
chamber (95) of the second compression mechanism (72).
[0116] In the first compression mechanism (71), the low-pressure
refrigerant is sucked into the first compression chamber (85)
through the first suction port (86). In the completely-closed first
compression chamber (85) which is blocked from the first suction
port (86), the refrigerant is compressed as the first piston (82)
moves. In such a state, first intermediate-pressure gas refrigerant
is injected into the completely-closed first compression chamber
(85) through the first injection pipe (35) and the first injection
port (89). As described above, the low-pressure refrigerant is
sucked into the first compression chamber (85) through the first
suction port (86), and the first intermediate-pressure gas
refrigerant is sucked into the first compression chamber (85)
through the first injection port (89). The first compression
mechanism (71) compresses the refrigerant sucked into the first
compression chamber (85), and discharges the compressed
high-pressure refrigerant to an internal space of the casing (51)
through the first discharge port (87).
[0117] In the second compression mechanism (72), low-pressure
refrigerant is sucked into the second compression chamber (95)
through the second suction port (96). In the completely-closed
second compression chamber (95) which is blocked from the second
suction port (96), the refrigerant is compressed as the second
piston (92) moves. In such a state, second intermediate-pressure
gas refrigerant is injected to the completely-closed second
compression chamber (95) through the second injection pipe (45) and
the second injection port (99). As described above, the
low-pressure refrigerant is sucked into the second compression
chamber (95) through the second suction port (96), and the second
intermediate-pressure gas refrigerant is sucked into the second
compression chamber (95) through the second injection port (99).
The second compression mechanism (72) compresses the refrigerant
sucked into the second compression chamber (95), and discharges the
compressed high-pressure refrigerant to the internal space of the
casing (51) through the second discharge port (97).
[0118] The high-pressure refrigerant is discharged from each of the
first compression mechanism (71) and the second compression
mechanism (72) to the internal space of the casing (51). The
high-pressure refrigerant discharged from the compression mechanism
(71, 72) upwardly flows through the internal space of the casing
(51), and is sent to the outside of the casing (51) through the
discharge pipe (52).
[0119] Although not shown in the figure, refrigerant oil is
accumulated in a bottom portion of the internal space of the casing
(51). The refrigerant oil flows into the oil supply path (69)
opening at a lower end of the drive shaft (65). Then, the
refrigerant oil is supplied to the compression mechanisms (71, 72),
and is used for lubrication of sliding portions of the compression
mechanisms (71, 72).
[0120] <Refrigeration Cycle>
[0121] The refrigeration cycle performed in the refrigerant circuit
(5) will be described with reference to a Mollier diagram
(pressure-enthalpy diagram) of FIG. 4. In the description below,
the "evaporator" means either one of the outdoor heat exchanger
(12) and the indoor heat exchanger (14), which is operated as the
evaporator (i.e., the indoor heat exchanger (14) in the cooling
operation, and the outdoor heat exchanger (12) in the heating
operation), and the "condenser" means either one of the outdoor
heat exchanger (12) and the indoor heat exchanger (14), which is
operated as the condenser (i.e., the outdoor heat exchanger (12) in
the cooling operation, and the indoor heat exchanger (14) in the
heating operation).
[0122] Refrigerant in a state at a point D (gas refrigerant having
a pressure P.sub.H) is discharged from the compressor (50). The
refrigerant in the state at the point D is changed to a state at a
point E by dissipating heat to air in the condenser, and then flows
into the one-way circulation pipe line (6). A mass flow rate of
high-pressure refrigerant flowing from the condenser to the one-way
circulation pipe line (6) is "m.sub.c."
[0123] A part of the high-pressure refrigerant flowing into the
one-way circulation pipe line (6) flows into the first branched
pipe (33), and the remaining refrigerant flows into the
high-pressure flow path (31) of the first heat exchanger (30). A
mass flow rate of high-pressure refrigerant flowing into the first
branched pipe (33) is "m.sub.i1." The high-pressure refrigerant
flowing into the first branched pipe (33) is expanded when passing
through the first expansion valve (34), and the pressure of the
high-pressure refrigerant is decreased from P.sub.H to P.sub.M1.
Then, such refrigerant is changed to first intermediate-pressure
refrigerant in a state at a point F (in a gas-liquid two-phase
state).
[0124] In the first heat exchanger (30), the high-pressure
refrigerant flowing through the high-pressure flow path (31) is
cooled, and the first intermediate-pressure refrigerant flowing
through the intermediate-pressure flow path (32) is evaporated into
first intermediate-pressure gas refrigerant. The high-pressure
refrigerant changed to a state at a point H due to reduction of the
enthalpy flows out from the high-pressure flow path (31) of the
first heat exchanger (30). Meanwhile, the first
intermediate-pressure gas refrigerant in a state at a point G flows
out from the intermediate-pressure flow path (32) of the first heat
exchanger (30). The first intermediate-pressure gas refrigerant
having the pressure P.sub.M1 is sent to the compressor (50) through
the first injection pipe (35). A mass flow rate of the first
intermediate-pressure gas refrigerant supplied to the compressor
(50) is "m.sub.i1."
[0125] A part of the high-pressure refrigerant in the state at the
point H, which flows out from the high-pressure flow path (31) of
the first heat exchanger (30) flows into the second branched pipe
(43), and the remaining refrigerant flows into the high-pressure
flow path (41) of the second heat exchanger (40). A mass flow rate
of the high-pressure refrigerant flowing into the second branched
pipe (43) is "m.sub.i2." The high-pressure refrigerant flowing into
the second branched pipe (43) is expanded when passing through the
second expansion valve (44), and the pressure of the high-pressure
refrigerant is decreased from P.sub.H to P.sub.M2. Then, such
refrigerant is changed to second intermediate-pressure refrigerant
in a state at a point I (in the gas-liquid two-phase state). The
second intermediate-pressure refrigerant in the state at the point
I is lower in any of a pressure, a specific enthalpy, and a
temperature than the first intermediate-pressure refrigerant in the
state at the point F. The second intermediate-pressure refrigerant
flows into the intermediate-pressure flow path (32) of the second
heat exchanger (40).
[0126] In the second heat exchanger (40), the high-pressure
refrigerant flowing through the high-pressure flow path (41) is
cooled, and the second intermediate-pressure refrigerant flowing
through the intermediate-pressure flow path (42) is evaporated into
second intermediate-pressure gas refrigerant. The high-pressure
refrigerant changed to a state at a point K due to the reduction of
the enthalpy flows out from the high-pressure flow path (41) of the
second heat exchanger (40). Meanwhile, the second
intermediate-pressure gas refrigerant in a state at a point J flows
out from the intermediate-pressure flow path (42) of the second
heat exchanger (40). The second intermediate-pressure gas
refrigerant having the pressure P.sub.M2 is sent to the compressor
(50) through the second injection pipe (45). A mass flow rate of
the second intermediate-pressure gas refrigerant supplied to the
compressor (50) is "m.sub.i2."
[0127] The high-pressure refrigerant in the state at the point K,
which flows out from the high-pressure flow path (41) of the second
heat exchanger (40) is expanded when passing through the main
expansion valve (13), and the pressure of the high-pressure
refrigerant is decreased from P.sub.H to P.sub.L. Then, such
refrigerant is changed to low-pressure refrigerant in a state at a
point L (in the gas-liquid two-phase state). The low-pressure
refrigerant flows into the evaporator, and absorbs heat from air.
After such refrigerant is evaporated into refrigerant in a state at
a point A, the refrigerant is sucked into the compressor (50). In
the compressor (50), the refrigerant in the state at the point A is
sucked into the first compression chamber (85) of the first
compression mechanism (71) and the second compression chamber (95)
of the second compression mechanism (72). A mass flow rate of the
low-pressure refrigerant sucked into the compressor (50) from the
evaporator is "m.sub.e."
[0128] In the first compression mechanism (71) of the compressor
(50), the refrigerant sucked into the first compression chamber
(85) is compressed, and the refrigerant in the first compression
chamber (85) is changed from the state at the point A to a state at
a point B. Meanwhile, the first intermediate-pressure gas
refrigerant in the state at the point G is injected to the
completely-closed first compression chamber (85) in the middle of a
compression process through the first injection port (89). In the
first compression chamber (85), the refrigerant which flows into
the first compression chamber (85) in the state at the point A and
is being compressed, and the first intermediate-pressure gas
refrigerant in the state at the point G, which flows into the first
compression chamber (85) through the first injection port (89) are
mixed together, and the refrigerant mixture is compressed into the
refrigerant in the state at the point D.
[0129] In the second compression mechanism (72) of the compressor
(50), the refrigerant sucked into the second compression chamber
(95) is compressed, and the refrigerant in the second compression
chamber (95) is changed from the state at the point A to a state at
a point B'. Meanwhile, the second intermediate-pressure gas
refrigerant in the state at the point J is injected to the
completely-closed second compression chamber (95) in the middle of
the compression process through the second injection port (99). In
the second compression chamber (95), the refrigerant which flows
into the second compression chamber (95) in the state at the point
A and is being compressed, and the second intermediate-pressure gas
refrigerant in the state at the point J, which flows into the
second compression chamber (95) through the second injection port
(99) are mixed together, and the refrigerant mixture is compressed
into the refrigerant in the state at the point D.
[0130] As described above, the main body (70) of the compressor
(50) sucks and compresses the low-pressure refrigerant (the mass
flow rate m.sub.e) sent from the evaporator, the first
intermediate-pressure gas refrigerant (the mass flow rate m.sub.i1)
supplied through the first injection pipe (35), and the second
intermediate-pressure gas refrigerant (the mass flow rate m.sub.i2)
supplied through the second injection pipe (45). Thus, a mass flow
rate m.sub.c of high-pressure refrigerant discharged from the
compressor (50) to the condenser is equal to a sum of the mass flow
rates of the low-pressure refrigerant, the first
intermediate-pressure gas refrigerant, and the second
intermediate-pressure gas refrigerant which are sucked into the
main body (70) of the compressor (50)
(m.sub.c=m.sub.e+m.sub.i1+m.sub.i2).
[0131] Advantages of First Embodiment
[0132] In the refrigerant circuit (5) of the air conditioner (1) of
the present embodiment, the first intermediate-pressure gas
refrigerant is generated in the first heat exchanger (30), and the
second intermediate-pressure gas refrigerant is generated in the
second heat exchanger (40). The first intermediate-pressure gas
refrigerant is higher in the pressure and the density than the
second intermediate-pressure gas refrigerant. In addition, in the
refrigerant circuit (5) of the air conditioner (1) of the present
embodiment, the second intermediate-pressure gas refrigerant is
supplied to the second compression mechanism (72) of the compressor
(50), whereas the first intermediate-pressure gas refrigerant
having the pressure and density higher than those of the second
intermediate-pressure gas refrigerant is supplied to the first
compression mechanism (71) of the compressor (50). Thus, according
to the present embodiment, the mass flow rate m.sub.c of
refrigerant discharged from the compressor (50) can be increased as
compared to a case where only the second intermediate-pressure gas
refrigerant is supplied to the compression mechanism (71, 72).
[0133] In the air conditioner (1) of the present embodiment, the
first intermediate-pressure gas refrigerant is injected to the
first compression chamber (85) of the first compression mechanism
(71) in the middle of the compression process, and the second
intermediate-pressure gas refrigerant is injected to the second
compression chamber (95) of the second compression mechanism (72)
in the middle of the compression process. Thus, only the mass flow
rate m.sub.c of refrigerant discharged from the compressor (50) to
the condenser can be increased without increasing the mass flow
rate m.sub.e of low-pressure refrigerant sucked into the compressor
(50) from the evaporator. That is, according to the present
embodiment, the mass flow rate of refrigerant discharged from the
compressor (50) can be increased without increasing a rotational
speed of the compression mechanism (71, 72) provided in the
compressor (50) (i.e., a rotational speed of the drive shaft (65)
for driving the piston (82, 92) of the compression mechanism (71,
72)). Consequently, while reducing an increase in electric power
consumed by the electric motor (60) of the compressor (50), the
mass flow rate of refrigerant discharged from the compressor (50)
can be increased, and an amount of heat released to air from
refrigerant (i.e., a heat dissipation amount of refrigerant) in the
condenser can be increased.
[0134] In the refrigerant circuit (5) of the air conditioner (1) of
the present embodiment, high-pressure refrigerant is cooled by
exchanging heat with the first intermediate-pressure refrigerant in
the first heat exchanger (30), and the high-pressure refrigerant
cooled in the first heat exchanger (30) is further cooled by
exchanging heat with the second intermediate-pressure refrigerant
(i.e., refrigerant having the pressure and temperature lower than
those of the first intermediate-pressure refrigerant) in the second
heat exchanger (40). Thus, according to the present embodiment, the
enthalpy of refrigerant flowing into the evaporator can be reduced
as compared to a case where high-pressure refrigerant sent from the
condenser to the evaporator exchanges heat only with the first
intermediate-pressure refrigerant. Consequently, an amount of heat
absorbed from air by refrigerant (i.e., a heat absorption amount of
refrigerant) in the evaporator can be increased.
[0135] As described above, according to the present embodiment, the
increase in mass flow rate of refrigerant in the condenser results
in the increase in heat dissipation amount of refrigerant in the
condenser. Further, the reduction in enthalpy of refrigerant
flowing into the evaporator results in the increase in heat
absorption amount of refrigerant in the evaporator. That is,
according to the present embodiment, both of the heat dissipation
amount of refrigerant in the condenser and the heat absorption
amount of refrigerant in the evaporator can be ensured. Thus,
according to the present embodiment, while reducing the increase in
power consumption of the air conditioner (1), a heating capacity
(i.e., an amount of heat released from refrigerant to room air in
the indoor heat exchanger (14) operated as the condenser) of the
air conditioner (1) can be increased, and a cooling capacity (i.e.,
an amount of heat absorbed from room air by refrigerant in the
indoor heat exchanger (14) operated as the evaporator) of the air
conditioner (1) can be also increased.
[0136] In the refrigerant circuit (5) of the air conditioner (1) of
the present embodiment, the enthalpy of refrigerant flowing into
the evaporator can be reduced as described above. Thus, while
maintaining the heat absorption amount of refrigerant in the
evaporator, the mass flow rate of refrigerant in the evaporator can
be decreased. When decreasing the mass flow rate of refrigerant in
the evaporator, a flow velocity of refrigerant in the evaporator is
reduced, and a pressure loss of refrigerant during a passage
through the evaporator is reduced. When reducing the pressure loss
of refrigerant in the evaporator, the pressure of low-pressure
refrigerant sucked into the compressor (50) is increased by an
amount equivalent to the reduction in the pressure loss in the
evaporator, and the power consumption by the electric motor (60) of
the compressor (50) is reduced. Thus, according to the present
embodiment, while maintaining the heat dissipation amount of
refrigerant in the evaporator, the power consumption of the
compressor (50) can be reduced. Consequently, a coefficient of
performance (COP) of the air conditioner (1) in the cooling
operation can be improved.
[0137] In a refrigerant circuit in which a multiple-stage
compression refrigeration cycle is performed, intermediate-pressure
gas refrigerant is supplied to each section between compressors.
That is, in, e.g., a refrigerant circuit in which a three-stage
compression refrigeration cycle is performed, intermediate-pressure
gas refrigerant is supplied between a compressor at a first stage
and a compressor at a second stage, and between the compressor at
the second stage and a compressor at a third stage.
[0138] On the other hand, in the refrigerant circuit (5) of the
present embodiment, the first and second intermediate-pressure gas
refrigerants with different pressures are generated in the enthalpy
reducing unit (20). Thus, in the refrigerant circuit of the present
embodiment, employment of a "configuration in which three
compression mechanisms are used to perform a three-stage
compression refrigeration cycle, the second intermediate-pressure
gas refrigerant is supplied between a compression mechanism at a
first stage and a compression mechanism at a second stage, and the
first intermediate-pressure gas refrigerant is supplied between the
compression mechanism at the second stage and a compression
mechanism at a third stage" is technically allowed.
[0139] However, if such a configuration is employed in the
refrigerant circuit of the present embodiment, there are problems
that operational efficiency of the air conditioner cannot be
sufficiently improved, and a manufacturing cost of the air
conditioner is increased. Such problems will be described
below.
[0140] Typically, a three-stage compression refrigeration cycle is
performed when only a low COP (coefficient of performance) can be
obtained in a two-stage compression refrigerant cycle or a
single-stage compression refrigeration cycle due to a large
difference between low and high pressure levels of the
refrigeration cycle. The low and high pressure levels of the
refrigeration cycle performed in a refrigerant circuit of an air
conditioner are values corresponding to a temperature inside a room
where a person is present or an outdoor temperature. It is less
likely that the room temperature or the outdoor temperature shows
an extremely high value or an extremely low value, and therefore
the difference between the low and high pressure levels of the
refrigeration cycle performed in the refrigerant circuit of the air
conditioner is not extremely increased under normal conditions.
[0141] Since the compression mechanism for compressing refrigerant
includes a plurality of members, a mechanical loss such as a
friction loss between the members is caused in the compression
mechanism. Thus, the greater number of compression mechanisms
results in a greater overall mechanical loss caused in each of the
compression mechanisms. In addition, the greater number of
compression mechanisms provided in the air conditioner results in a
higher manufacturing cost of the air conditioner. For such reasons,
even when the "difference between the low and high pressure levels
of the refrigeration cycle is not so large, and a sufficiently high
COP can be obtained in the single-stage compression refrigeration
cycle," if the "configuration in which the three compression
mechanisms are used to perform the three-stage compression
refrigeration cycle" is employed, there are problems that an
increase in mechanical loss in the compression mechanism causes
degradation of the operational efficiency of the air conditioner,
and an increase in the number of compression mechanisms causes an
increase in manufacturing cost of the air conditioner.
[0142] On the other hand, in the refrigerant circuit (5) of the air
conditioner (1) of the present embodiment, in which the
single-stage compression refrigeration cycle is performed, the
first intermediate-pressure gas refrigerant and the second
intermediate-pressure gas refrigerant generated in the enthalpy
reducing unit (20) are sucked into the first compression mechanism
(71) and the second compression mechanism (72), respectively. That
is, according to the present embodiment, both of the first and
second intermediate-pressure gas refrigerants with different
pressures can be sucked into the compressor (50) in which a
single-stage compression is performed. Thus, according to the
present embodiment, while using the two compression mechanisms (71,
72), the first and second intermediate-pressure gas refrigerants
with different pressures can be processed, thereby solving the
problems such as the increase in mechanical loss of the compressor
(50) and the increase in manufacturing cost of the air conditioner
(1) due to the increase in the number of compression
mechanisms.
Second Embodiment of the Invention
[0143] A second embodiment of the present invention will be
described. In the present embodiment, the configuration of the
refrigerant circuit (5) is changed in the air conditioner (1) of
the first embodiment. Differences between a refrigerant circuit (5)
of the present embodiment and the refrigerant circuit (5) of the
first embodiment will be described.
[0144] As illustrated in FIG. 5, the refrigerant circuit (5) of the
present embodiment is different from the refrigerant circuit (5) of
the first embodiment in a connection position of a second branched
pipe (43). Specifically, in the refrigerant circuit (5) of the
present embodiment, one end of the second branched pipe (43) is
connected to a first branched pipe (33) between a first expansion
valve (34) and a first heat exchanger (30). The refrigerant circuit
(5) of the present embodiment is similar to the refrigerant circuit
(5) of the first embodiment in that the other end of the second
branched pipe (43) is connected to a second heat exchanger
(40).
[0145] A refrigeration cycle performed in the refrigerant circuit
(5) of the present embodiment will be described. Differences
between such a refrigeration cycle and the refrigeration cycle
performed in the refrigerant circuit (5) of the first embodiment
will be described below. In the description below, an "evaporator"
means either one of an outdoor heat exchanger (12) and an indoor
heat exchanger (14), which is operated as an evaporator, and a
"condenser" means either one of the outdoor heat exchanger (12) and
the indoor heat exchanger (14), which is operated as a
condenser.
[0146] As illustrated in a Mollier diagram (pressure-enthalpy
diagram) of FIG. 6, the refrigeration cycle performed in the
refrigerant circuit (5) of the present embodiment is different from
the refrigeration cycle performed in the refrigerant circuit (5) of
the first embodiment in a state change of refrigerant flowing
through the first branched pipe (33) and the second branched pipe
(43).
[0147] Specifically, in the refrigerant circuit (5) of the present
embodiment, a part of high-pressure refrigerant (refrigerant in a
state at a point D) flowing into a one-way circulation pipe line
(6) through a bridge circuit (15) flows into the first branched
pipe (33). The high-pressure refrigerant flowing into the first
branched pipe (33) is expanded when passing through the first
expansion valve (34), and the pressure of the high-pressure
refrigerant is decreased from P.sub.H to P.sub.M1. Then, such
refrigerant is changed to first intermediate-pressure refrigerant
in a state at a point F. A part of the first intermediate-pressure
refrigerant flows into an intermediate-pressure flow path (32) of
the first heat exchanger (30), and the remaining refrigerant flows
into the second branched pipe (43). The first intermediate-pressure
refrigerant flowing into the intermediate-pressure flow path (32)
of the first heat exchanger (30) is evaporated into first
intermediate-pressure gas refrigerant by absorbing heat from
high-pressure refrigerant flowing through a high-pressure flow path
(31) of the first heat exchanger (30), and is supplied to a first
compression mechanism (71) of a compressor (50). The high-pressure
refrigerant flowing through the high-pressure flow path (31) of the
first heat exchanger (30) is changed to a state at a point H due to
reduction of an enthalpy.
[0148] Meanwhile, the first intermediate-pressure refrigerant
flowing into the second branched pipe (43) is expanded when passing
through a second expansion valve (44), and the pressure of the
first intermediate-pressure refrigerant is decreased from P.sub.M1
to P.sub.M2. Then, such refrigerant is changed to second
intermediate-pressure refrigerant in a state at a point I. All of
the second intermediate-pressure refrigerant flows into an
intermediate-pressure flow path (42) of the second heat exchanger
(40). The second intermediate-pressure refrigerant flowing into the
intermediate-pressure flow path (42) of the second heat exchanger
(40) is evaporated into second intermediate-pressure gas
refrigerant by absorbing heat from high-pressure refrigerant
flowing through a high-pressure flow path (41) of the second heat
exchanger (40), and is supplied to a second compression mechanism
(72) of the compressor (50). The high-pressure refrigerant flowing
through the high-pressure flow path (41) of the second heat
exchanger (40) is changed to a state at a point K due to the
reduction of the enthalpy.
[0149] First Variation of Second Embodiment
[0150] As illustrated in FIG. 7, in the refrigerant circuit (5) of
the present embodiment, one end of the second branched pipe (43)
may be connected to the first branched pipe (33) upstream the first
expansion valve (34).
[0151] In a refrigerant circuit (5) of the present variation, a
refrigeration cycle illustrated in the Mollier diagram of FIG. 6 is
performed. In the refrigerant circuit (5), a part of high-pressure
refrigerant (refrigerant in a state at a point E in FIG. 6) flowing
into the first branched pipe (33) from the one-way circulation pipe
line (6) is sent to the first expansion valve (34), and the
remaining refrigerant flows into the second branched pipe (43). The
high-pressure refrigerant sent to the first expansion valve (34) is
expanded when passing through the first expansion valve (34), and
the pressure of the high-pressure refrigerant is decreased from
P.sub.H to P.sub.M1. Then, such refrigerant is changed to first
intermediate-pressure refrigerant in the state at the point F in
FIG. 6, and flows into the first heat exchanger (30). Meanwhile,
the high-pressure refrigerant flowing into the second branched pipe
(43) is expanded when passing through the second expansion valve
(44), and the pressure of the high-pressure refrigerant is
decreased from P.sub.H to P.sub.M2. Then, such refrigerant is
changed to second intermediate-pressure refrigerant in the state at
the point I in FIG. 6, and flows into the second heat exchanger
(40).
[0152] Second Variation of Second Embodiment
[0153] As illustrated in FIG. 8, in the refrigerant circuit (5) of
the present embodiment, a gas-liquid separator (23) may be provided
in the middle of the first branched pipe (33), and one end of the
second branched pipe (43) may be connected to the gas-liquid
separator (23).
[0154] Specifically, in a refrigerant circuit (5) of the present
variation, the first branched pipe (33) is divided into an upstream
section (33a) and a downstream section (33b). One end of the
upstream section (33a) of the first branched pipe (33) is connected
to the one-way circulation pipe line (6) upstream the first heat
exchanger (30), and the other end of the upstream section (33a) is
connected to an inlet of the gas-liquid separator (23). The first
expansion valve (34) is provided in the upstream section (33a) of
the first brandied pipe (33). On the other hand, one end of the
downstream section (33b) of the first branched pipe (33) is
connected to a gas refrigerant outlet of the gas-liquid separator
(23), and the other end of the downstream section (33b) is
connected to the intermediate-pressure flow path (32) of the first
heat exchanger (30). One end of the second branched pipe (43) is
connected to a liquid refrigerant outlet of the gas-liquid
separator (23), and the other end of the second branched pipe (43)
is connected to the intermediate-pressure flow path (42) of the
second heat exchanger (40).
[0155] In the refrigerant circuit (5) of the present variation, a
refrigeration cycle illustrated in a Mollier diagram of FIG. 9 is
performed. In the refrigerant circuit (5), high-pressure
refrigerant (refrigerant in the state at the point E) flowing into
the upstream section (33a) of the first branched pipe (33) from the
one-way circulation pipe line (6) is expanded when passing through
the first expansion valve (34), and the pressure of the
high-pressure refrigerant is decreased from P.sub.H to P.sub.M1.
Then, such refrigerant is changed to first intermediate-pressure
refrigerant in the state at the point F, and flows into the
gas-liquid separator (23). The first intermediate-pressure
refrigerant flowing into the gas-liquid separator (23) is separated
into saturated liquid refrigerant in a state at a point F' and
saturated gas refrigerant in a state at a point F''.
[0156] The saturated gas refrigerant in the state at the point F''
flows into the intermediate-pressure flow path (32) of the first
heat exchanger (30) through the downstream section (33b) of the
first branched pipe (33), and is changed to first
intermediate-pressure gas refrigerant in a state at a point G by
absorbing heat from high-pressure refrigerant flowing through the
high-pressure flow path (31) of the first heat exchanger (30). The
high-pressure refrigerant flowing through the high-pressure flow
path (31) of the first heat exchanger (30) is cooled to the state
at the point H by the refrigerant flowing through the
intermediate-pressure flow path (32).
[0157] Meanwhile, the saturated liquid refrigerant in the state at
the point F' flows into the second branched pipe (43). The
refrigerant flowing into the second branched pipe (43) is expanded
when passing through the second expansion valve (44), and the
pressure of the refrigerant is decreased from P.sub.M1 to P.sub.M2.
Then, such refrigerant is changed to second intermediate-pressure
refrigerant in the state at the point I, and flows into the second
heat exchanger (40). In the second heat exchanger (40), the second
intermediate-pressure refrigerant flowing through the
intermediate-pressure flow path (42) is evaporated into second
intermediate-pressure gas refrigerant in a state at a point J by
absorbing heat from high-pressure refrigerant flowing through the
high-pressure flow path (41). The high-pressure refrigerant flowing
through the high-pressure flow path (41) of the second heat
exchanger (40) is cooled to the state at the point K by the
refrigerant flowing through the intermediate-pressure flow path
(42).
Third Embodiment of the Invention
[0158] A third embodiment of the present invention will be
described. In the present embodiment, the configuration of the
refrigerant circuit (5) is changed in the air conditioner (1) of
the first embodiment. Differences between a refrigerant circuit (5)
of the present embodiment and the refrigerant circuit (5) of the
first embodiment will be described.
[0159] As illustrated in FIG. 10, in the circuit (5) of the present
embodiment, the first branched pipe (33), the second branched pipe
(43), the first heat exchanger (30), and the second heat exchanger
(40) of the first embodiment are omitted. In the refrigerant
circuit (5) of the present embodiment, a first expansion valve
(37), a first gas-liquid separator (36), a second expansion valve
(47), and a second gas-liquid separator (46) are provided in a
one-way circulation pipe line (6).
[0160] In the refrigerant circuit (5) of the present embodiment,
the first expansion valve (37), the first gas-liquid separator
(36), the second expansion valve (47), and the second gas-liquid
separator (46) are arranged in this order from an inlet end of the
one-way circulation pipe line (6) to an outlet end of the one-way
circulation pipe line (6). In the refrigerant circuit (5) of the
present embodiment, the inlet end of the one-way circulation pipe
line (6) is connected to an inlet of the first gas-liquid separator
(36) through the first expansion valve (37). A gas refrigerant
outlet of the first gas-liquid separator (36) is connected to a
first injection pipe (35), and a liquid refrigerant outlet of the
first gas-liquid separator (36) is connected to an inlet of the
second gas-liquid separator (46) through the second expansion valve
(47). A gas refrigerant outlet of the second gas-liquid separator
(46) is connected to a second injection pipe (45), and a liquid
refrigerant outlet of the second gas-liquid separator (46) is
connected to a main expansion valve (13).
[0161] A refrigeration cycle performed in the refrigerant circuit
(5) of the present embodiment will be described. Differences
between such a refrigeration cycle and the refrigeration cycle
performed in the refrigerant circuit (5) of the first embodiment
will be described below. In the description below, an "evaporator"
means either one of an outdoor heat exchanger (12) and an indoor
heat exchanger (14), which is operated as an evaporator, and a
"condenser" means either one of the outdoor heat exchanger (12) and
the indoor heat exchanger (14), which is operated as a
condenser.
[0162] As illustrated in a Mollier diagram of FIG. 11, the
refrigeration cycle performed in the refrigerant circuit (5) of the
present embodiment is different from the refrigeration cycle
performed in the refrigerant circuit (5) of the first embodiment in
a state change of refrigerant flowing through the one-way
circulation pipe line (6) of the refrigerant circuit (5).
[0163] Specifically, in the refrigerant circuit (5) of the present
embodiment, high-pressure refrigerant (refrigerant in a state at a
point D) flowing into the one-way circulation pipe line (6) through
a bridge circuit (15) is expanded when passing through the first
expansion valve (37), and the pressure of the high-pressure
refrigerant is decreased from P.sub.H to P.sub.M1. Then, such
refrigerant is changed to refrigerant in a state at a point F (in a
gas-liquid two-phase state), and flows into the first gas-liquid
separator (36). The refrigerant flowing into the first gas-liquid
separator (36) is separated into saturated liquid refrigerant in a
state at a point F' and saturated gas refrigerant in a state at a
point F''. The saturated liquid refrigerant in the state at the
point F' flows out from the first gas-liquid separator (36) to the
second expansion valve (47). The saturated gas refrigerant in the
state at the point F'' is supplied to a first compression mechanism
(71) of a compressor (50) through the first injection pipe
(35).
[0164] The saturated liquid refrigerant in the state at the point
F', which flows out from the first gas-liquid separator (36) is
expanded when passing through the second expansion valve (47), and
the pressure of the saturated liquid refrigerant is decreased from
P.sub.M1 to P.sub.M2. Then, such refrigerant is changed to
refrigerant in a state at a point I (in the gas-liquid two-phase
state), and flows into the second gas-liquid separator (46). The
refrigerant flowing into the second gas-liquid separator (46) is
separated into saturated liquid refrigerant in a state at a point
I' and saturated gas refrigerant in a state at a point I''. The
saturated liquid refrigerant in the state at the point I' flows out
from the second gas-liquid separator (46) to the main expansion
valve (13). The saturated gas refrigerant in the state at the point
I'' is supplied to a second compression mechanism (72) of the
compressor (50) through the second injection pipe (45).
[0165] The saturated liquid refrigerant in the state at the point
I', which flows out from the second gas-liquid separator (46) is
expanded when passing through the main expansion valve (13), and
the pressure of the saturated liquid refrigerant is decreased from
P.sub.M2 to P.sub.L. Then, such refrigerant is changed to
refrigerant in a state at a point L (in the gas-liquid two-phase
state). The low-pressure refrigerant in the state at the point L is
supplied to the evaporator after passing through the main expansion
valve (13).
Other Embodiment
[0166] First Variation
[0167] In the first and second embodiments, the first heat
exchanger (30) and the second heat exchanger (40) may form a single
heat exchange member (100).
[0168] As illustrated in FIGS. 12 and 13, the heat exchange member
(100) is integrally formed by bonding four flat pipes (101-104) and
six headers (111-116) together by, e.g., brazing.
[0169] The flat pipe (101-104) is formed so as to have an oval
cross section. A plurality of fluid paths extending one end of the
flat pipe (101-104) to the other end of the flat pipe (101-104) are
formed in the flat pipe (101-104).
[0170] In the heat exchange member (100), the first flat pipe (101)
and the fourth flat pipe (104) are stacked so that axial directions
of the first flat pipe (101) and the fourth flat pipe (104) are
parallel to each other, and flat portions of outer surfaces of the
first flat pipe (101) and the fourth flat pipe (104) closely
contact each other. In addition, in the heat exchange member (100),
the second flat pipe (102) and the third flat pipe (103) are
stacked so that axial directions of the second flat pipe (102) and
the third flat pipe (103) are parallel to each other, and flat
portions of outer surfaces of the second flat pipe (102) and the
third flat pipe (103) closely contact each other.
[0171] The header (111-116) is formed in a hollow cylindrical shape
which is closed at both ends. The header (111-116) is arranged so
that an axial direction of the header (111-116) is perpendicular to
the axial direction of the flat pipe (101-104).
[0172] The first header (111) is connected to one end of the first
flat pipe (101). The second header (112) is connected to the other
end of the first flat pipe (101). One end of the second flat pipe
(102) is connected to the second header (112) from a side opposite
to the first flat pipe (101). The other end of the second flat pipe
(102) is connected to the third header (113).
[0173] One end of the third flat pipe (103) is connected to the
fourth header (114). The other end of the third flat pipe (103) is
connected to the fifth header (115). One end of the fourth flat
pipe (104) is connected to the fifth header (115) from a side
opposite to the third flat pipe (103). Further, an internal space
of the fifth header (115) is divided into a portion communicated
only with the third flat pipe (103) and a portion communicated only
with the fourth flat pipe (104). The other end of the fourth flat
pipe (104) is connected to the sixth header (116).
[0174] Pipes forming the refrigerant circuit (5) are connected to
the heat exchange member (100) (see FIG. 13). The one-way
circulation pipe line (6) extending from the bridge circuit (15) is
connected to the four-way valve (11). An inlet end of the second
branched pipe (43) is connected to the second header (112). The
one-way circulation pipe line (6) extending toward the main
expansion valve (13) is connected to the third header (113). An
outlet end of the second branched pipe (43) is connected to the
fourth header (114). The second injection pipe (45) is connected to
the portion of the fifth header (115), which is communicated with
the third flat pipe (103). An outlet end of the first branched pipe
(33) is connected to the portion of the fifth header (115), which
is connected to the fourth flat pipe (104). The first injection
pipe (35) is connected to the sixth header (116).
[0175] In the heat exchange member (100), the first flat pipe
(101), the fourth flat pipe (104), the first header (111), the
second header (112), the fifth header (115), and the sixth header
(116) form the first heat exchanger (30). Specifically, in the heat
exchange member (100), the fluid paths of the first flat pipe (101)
serve as the high-pressure flow path (31) of the first heat
exchanger (30), and the fluid paths of the fourth flat pipe (104)
serve as the intermediate-pressure flow path (32) of the first heat
exchanger (30). Since the first flat pipe (101) and the fourth flat
pipe (104) are bonded together with the first flat pipe (101) and
the fourth flat pipe (104) being stacked in the heat exchange
member (100), heat is exchanged between refrigerant flowing through
the high-pressure flow path (31) and refrigerant flowing through
the intermediate-pressure flow path (32).
[0176] In addition, in the heat exchange member (100), the second
flat pipe (102), the third flat pipe (103), the second header
(112), the third header (113), the fourth header (114), and the
fifth header (115) form the second heat exchanger (40).
Specifically, in the heat exchange member (100), the fluid paths of
the second flat pipe (102) serve as the high-pressure flow path
(41) of the second heat exchanger (40), and the fluid paths of the
third flat pipe (103) serve as the intermediate-pressure flow path
(42) of the second heat exchanger (40). Since the second flat pipe
(102) and the third flat pipe (103) are bonded together with the
second flat pipe (102) and the third flat pipe (103) being stacked
in the heat exchange member (100), heat is exchanged between
refrigerant flowing through the high-pressure flow path (41) and
refrigerant flowing through the intermediate-pressure flow path
(42).
[0177] Second Variation
[0178] In each of the first to third embodiments, the first
compression mechanism (71) and the second compression mechanism
(72) may be provided in separate compressors (50a, 50b).
Differences of the refrigerant circuit (5) of the first embodiment,
to which the present variation is applied, from the refrigerant
circuit (5) of the first embodiment will be described.
[0179] As illustrated in FIG. 14, in the refrigerant circuit (5) of
the present variation, the first compressor (50a) and the second
compressor (50b) are provided. The first compressor (50a) is a
hermetic compressor including a first compression mechanism (71).
In a casing (51a) of the first compressor (50a), the first
compression mechanism (71), an electric motor (60a), and a drive
shaft (65a) connecting between the first compression mechanism (71)
and the electric motor (60a) are accommodated. A discharge pipe
(52a) is provided in the casing (51a) of the first compressor
(50a), and a first suction pipe (53) is connected to the first
compression mechanism (71). On the other hand, the second
compressor (50b) is a hermetic compressor including a second
compression mechanism (72). In a casing (Mb) of the second
compressor (50b), the second compression mechanism (72), an
electric motor (60b), a drive shaft (65b) connecting the second
compression mechanism (72) and the electric motor (60b) are
accommodated. A discharge pipe (52b) is provided in the casing
(51b) of the second compressor (50b), and a second suction pipe
(54) is connected to the second compression mechanism (72).
[0180] In the refrigerant circuit (5) of the present variation,
both of the discharge pipe (52a) of the first compressor (50a) and
the discharge pipe (52b) of the second compressor (50b) are
connected to the first port of the four-way valve (11). In
addition, in the refrigerant circuit (5), both of the first suction
pipe (53) of the first compressor (50a) and the second suction pipe
(54) of the second compressor (50b) are connected to the second
port of the four-way valve (11). The first injection pipe (35) is
connected to the first injection port (89) of the first compression
mechanism (71) provided in the first compressor (50a). The second
injection pipe (45) is connected to the second injection port (99)
of the second compression mechanism (72) provided in the second
compressor (50b).
[0181] Note that each of the first compression mechanism (71) and
the second compression mechanism (72) of the present variation may
be a rotary fluid machine including a pair of cylinders and a pair
of pistons, or a rotary fluid machine including a plurality of
cylinders and a plurality of pistons.
[0182] Third Variation
[0183] In each of the first to third embodiments, the compressor
(50) may be configured to perform a two-stage compression.
Differences of the refrigerant circuit (5) of the first embodiment,
to which the present variation is applied, from the refrigerant
circuit (5) of the first embodiment will be described.
[0184] As illustrated in FIG. 15, the compressor (50) of the
present variation includes a single suction pipe (55). The suction
pipe (55) penetrates the casing (51), and one end of the suction
pipe (55) is connected to the second suction port (96) of the
second compression mechanism (72). In addition, a connection path
(57) is provided in the compressor (50). The connection path (57)
allows a communication between the second discharge port (97) of
the second compression mechanism (72) and the first suction port
(86) of the first compression mechanism (71). Note that the
connection path (57) may be defined by a pipe exposed to the
outside of the casing (51), or may be defined by a space formed
inside the main body (70) of the compressor (50). As in the first
embodiment, in the compressor (50) of the present variation, the
first injection pipe (35) is connected to the first injection port
(89) of the first compression mechanism (71), and the second
injection pipe (45) is connected to the second injection port (99)
of the second compression mechanism (72).
[0185] An operation of the compressor (50) of the present variation
will be described with reference to FIG. 16. FIG. 16 is a Mollier
diagram illustrating a two-stage compression refrigeration cycle
performed in the refrigerant circuit (5) of the present
variation.
[0186] Low-pressure refrigerant in a state at a point A is sucked
into the compressor (50) of the present variation. The low-pressure
refrigerant flowing into the suction pipe (55) of the compressor
(50) is sucked into the second compression chamber (95) of the
second compression mechanism (72). In the second compression
mechanism (72), the low-pressure refrigerant sucked into the second
compression chamber (95) is compressed, and the refrigerant in the
second compression chamber (95) is changed from the state at the
point A to a state at a point B.sub.1. Second intermediate-pressure
gas refrigerant in a state at a point J is injected to the second
compression mechanism (72) through the second injection pipe (45).
In the second compression chamber (95) of the second compression
mechanism (72), the refrigerant which flows into the second
compression chamber (95) in the state at the point A and is being
compressed, and the second intermediate-pressure gas refrigerant
flowing into the second compression chamber (95) through the second
injection pipe (45) are mixed together, and the refrigerant mixture
is compressed into a state at a point M. The second compression
mechanism (72) discharges the refrigerant compressed into
refrigerant in the state at the point M.
[0187] The refrigerant discharged from the second compression
mechanism (72) is sucked into the first compression mechanism (71)
through the connection path (57). In the first compression
mechanism (71), the refrigerant sucked into the first compression
chamber (85) is compressed, and the refrigerant in the first
compression chamber (85) is changed from the state at the point M
to a state at a point C.sub.1. First intermediate-pressure gas
refrigerant in a state at a point G is injected to the first
compression mechanism (71) through the first injection pipe (35).
In the first compression chamber (85) of the first compression
mechanism (71), the refrigerant which flows into the first
compression chamber (85) in the state at the point M and is being
compressed, and the first intermediate-pressure gas refrigerant
flowing into the first compression chamber (85) through the first
injection pipe (35) are mixed together, and the refrigerant mixture
is compressed into refrigerant in a state at a point D. The first
compression mechanism (71) discharges the refrigerant compressed
into the state at the point D. The refrigerant discharged from the
first compression mechanism (71) is sent to the outside of the
casing (51) through the discharge pipe (52).
[0188] As described above, the compressor (50) of the present
variation sucks and compresses the low-pressure refrigerant (the
mass flow rate m.sub.c) sent from the evaporator, the first
intermediate-pressure gas refrigerant (the mass flow rate m.sub.i1)
supplied through the first injection pipe (35), and the second
intermediate-pressure gas refrigerant (the mass flow rate m.sub.i2)
supplied through the second injection pipe (45). Thus, the mass
flow rate m.sub.c of high-pressure refrigerant discharged from the
compressor (50) to the condenser is equal to a sum of the mass flow
rates of the low-pressure refrigerant, the first
intermediate-pressure gas refrigerant, and the second
intermediate-pressure gas refrigerant which are sucked into the
compressor (50) (m.sub.c=m.sub.e+m.sub.i1+m.sub.i2).
[0189] In the refrigerant circuit (5) of the air conditioner (1) of
the present variation, in which the two-state compression
refrigeration cycle is performed, the first and second
intermediate-pressure gas refrigerants generated in the enthalpy
reducing unit (20) are sucked into the compressor (50). That is,
according to the present variation, both of the first and second
intermediate-pressure gas refrigerants with different pressures can
be sucked into the compressor (50) performing the two-stage
compression. Thus, according to the present variation, while using
the two compression mechanisms (71, 72), the first and second
intermediate-pressure gas refrigerants with different pressures can
be processed, thereby solving the problems such as the increase in
mechanical loss of the compressor (50) and the increase in
manufacturing cost of the air conditioner (1) due to the increase
in the number of compression mechanisms.
[0190] Fourth Variation
[0191] In the refrigerant circuit (5) of the third variation, a
connection position of the first injection pipe (35) or the second
injection pipe (45) to the compressor (50) may be changed.
Differences of the refrigerant circuit (5) illustrated in FIG. 15,
to which the present variation is applied, from the refrigerant
circuit (5) illustrated in FIG. 15 will be described.
[0192] As illustrated in FIG. 17, the first injection pipe (35) may
be connected not to the first compression mechanism (71) but to the
connection path (57). In such a case, in the first compression
mechanism (71), the first injection port (89) is omitted. Note that
the refrigerant circuit (5) of the present variation is similar to
the refrigerant circuit (5) illustrated in FIG. 15 in that the
second injection pipe (45) is connected to the second compression
mechanism (72).
[0193] An operation of the compressor of the present variation will
be described with reference to FIG. 18. FIG. 18 is a Mollier
diagram illustrating a two-stage compression refrigeration cycle
performed in the refrigerant circuit (5) of the present
variation.
[0194] In the refrigerant circuit (5) illustrated in FIG. 17,
low-pressure refrigerant in a state at a point A is sucked into the
compressor (50). The low-pressure refrigerant flowing into the
suction pipe (55) of the compressor (50) is sucked into the second
compression chamber (95) of the second compression mechanism (72).
In the second compression mechanism (72), the low-pressure
refrigerant sucked into the second compression chamber (95) is
compressed, and the refrigerant in the second compression chamber
(95) is changed from the state at the point A to a state at a point
B.sub.1. Second intermediate-pressure gas refrigerant in a state at
a point J is injected to the second compression mechanism (72)
through the second injection pipe (45). In the second compression
chamber (95) of the second compression mechanism (72), the
refrigerant which flows into the second compression chamber (95) in
the state at the point A and is being compressed, and the second
intermediate-pressure gas refrigerant flowing into the second
compression chamber (95) through the second injection pipe (45) are
mixed together, and the refrigerant mixture is compressed into
refrigerant in a state at a point C.sub.1. The second compression
mechanism (72) discharges the refrigerant compressed into the state
at the point C.sub.1.
[0195] The refrigerant discharged from the second compression
mechanism (72) flows into the connection path (57). First
intermediate-pressure gas refrigerant in a state at a point G is
injected to the connection path (57) through the first injection
pipe (35). In the connection path (57), the refrigerant in the
state at the point C.sub.1 and the first intermediate-pressure gas
refrigerant in the state at the point G are mixed into refrigerant
in a state at a point C.sub.2. The first compression mechanism (71)
sucks the refrigerant in the state indicated by the point C.sub.2
through the connection path (57).
[0196] In the first compression mechanism (71), the refrigerant
sucked into the first compression chamber (85) is compressed, and
the refrigerant in the first compression chamber (85) is changed
from the state at the point C.sub.2 to a state at a point D. The
first compression mechanism (71) discharges the refrigerant
compressed into the state at the point D. The refrigerant
discharged from the first compression mechanism (71) is sent to the
outside of the casing (51) through the discharge pipe (52).
[0197] As illustrated in FIG. 19, the second injection pipe (45)
may be connected not to the second compression mechanism (72) but
to the connection path (57). In such a case, in the second
compression mechanism (72), the second injection port (99) is
omitted. Note that the refrigerant circuit (5) of the present
variation is similar to the refrigerant circuit (5) illustrated in
FIG. 15 in that the first injection pipe (35) is connected to the
first compression mechanism (71).
[0198] An operation of the compressor (50) of the present variation
will be described with reference to FIG. 18.
[0199] In the refrigerant circuit (5) illustrated in FIG. 18,
low-pressure refrigerant in the state at the point A is sucked into
the compressor (50). The low-pressure refrigerant flowing into the
suction pipe (55) of the compressor (50) is sucked into the second
compression chamber (95) of the second compression mechanism (72),
and is compressed. Then, such refrigerant is changed from the state
at the point A to the state at the point B.sub.1. The second
compression mechanism (72) discharges the refrigerant changed to
the state at the point B.sub.1.
[0200] The refrigerant discharged from the second compression
mechanism (72) flows into the connection path (57). Second
intermediate-pressure gas refrigerant in the state at the point J
is injected to the connection path (57) through the second
injection pipe (45). In the connection path (57), the refrigerant
in the state at the point B.sub.1 and the second
intermediate-pressure gas refrigerant in the state at the point J
are mixed into refrigerant in a state at a point B.sub.2. The first
compression mechanism (71) sucks the refrigerant in the state at
the point B.sub.2 through the connection path (57).
[0201] In the first compression mechanism (71), the refrigerant
sucked into the first compression chamber (85) is compressed, and
the refrigerant in the first compression chamber (85) is changed
from the state at the point B.sub.2 to the state at the point
C.sub.1. First intermediate-pressure gas refrigerant in the state
at the point G is injected to the first compression mechanism (71)
through the first injection pipe (35). In the first compression
chamber (85) of the first compression mechanism (71), the
refrigerant which flows into the first compression chamber (85) in
the state at the point B.sub.2 and is being compressed, and the
first intermediate-pressure gas refrigerant flowing into the first
compression chamber (85) through the first injection pipe (35) are
mixed together, and the refrigerant mixture is compressed into
refrigerant in the state at the point D. The first compression
mechanism (71) discharges the refrigerant compressed into the state
at the point D. The refrigerant discharged from the first
compression mechanism (71) is sent to the outside of the casing
(51) through the discharge pipe (52).
[0202] Fifth Variation
[0203] In each of the third and fourth variations, the first
compression mechanism (71) and the second compression mechanism
(72) may be provided in separate compressors (50a, 50b).
[0204] First, differences of the refrigerant circuit (5) of the
second variation illustrated in FIG. 15, to which the present
variation is applied, from the refrigerant circuit (5) illustrated
in FIG. 15 will be described.
[0205] As illustrated in FIG. 20, if the present variation is
applied to the refrigerant circuit (5) illustrated in FIG. 15, the
first compressor (50a) and the second compressor (50b) are provided
in the refrigerant circuit (5). The first compressor (50a) is the
hermetic compressor including the first compression mechanism (71).
In the casing (51a) of the first compressor (50a), the first
compression mechanism (71), the electric motor (60a), and the drive
shaft (65a) connecting the first compression mechanism (71) and the
electric motor (60a) are accommodated. The discharge pipe (52a) is
provided in the casing (51a) of the first compressor (50a), and the
suction pipe (53) is connected to the first compression mechanism
(71). On the other hand, the second compressor (50b) is the
hermetic compressor including the second compression mechanism
(72). In the casing (51b) of the second compressor (50b), the
second compression mechanism (72), the electric motor (60b), and
the drive shaft (65b) connecting the second compression mechanism
(72) and the electric motor (60b) are accommodated. The discharge
pipe (52b) is provided in the casing (51b) of the second compressor
(50b), and the suction pipe (54) is connected to the second
compression mechanism (72).
[0206] In the refrigerant circuit (5) of the present variation, the
discharge pipe (52a) of the first compressor (50a) is connected to
the first port of the four-way valve (11), and the suction pipe
(54) of the second compressor (50b) is connected to the second port
of the four-way valve (11). The discharge pipe (52b) of the second
compressor (50b) and the first suction pipe (53) of the first
compressor (50a) are connected together by a connection pipe (58).
The first injection pipe (35) is connected to the first injection
port (89) of the first compression mechanism (71) provided in the
first compressor (50a). The second injection pipe (45) is connected
to the second injection port (99) of the second compression
mechanism (72) provided in the second compressor (50b).
[0207] Next, the refrigerant circuit (5) of the second variation
illustrated in FIG. 17, to which the present variation is applied
will be described with reference to FIG. 21. The refrigerant
circuit (5) illustrated in FIG. 21 is different from the
refrigerant circuit (5) illustrated in FIG. 20 only in a connection
position of the first injection pipe (35).
[0208] Specifically, in the refrigerant circuit (5) illustrated in
FIG. 21, the first injection pipe (35) is connected not to the
first compression mechanism (71) but to the connection pipe (58).
In the first compression mechanism (71), the first injection port
(89) is omitted. In the refrigerant circuit (5), the second
compression mechanism (72) of the second compressor (50b)
compresses and discharges low-pressure refrigerant sucked through
the suction pipe (54) and second intermediate-pressure gas
refrigerant flowing through the second injection pipe (45). The
first compression mechanism (71) of the first compressor (50a)
sucks the refrigerant discharged from the second compressor (50b)
and first intermediate-pressure gas refrigerant flowing into the
connection pipe (58) from the first injection pipe (35), and
compresses and discharges the sucked refrigerant.
[0209] Finally, the refrigerant circuit (5) of the second variation
illustrated in FIG. 19, to which the present variation is applied
will be described with reference to FIG. 22. The refrigerant
circuit (5) illustrated in FIG. 22 is different from the
refrigerant circuit (5) illustrated in FIG. 20 only in a connection
position of the second injection pipe (45).
[0210] Specifically, in the refrigerant circuit (5) illustrated in
FIG. 22, the second injection pipe (45) is connected not to the
second compression mechanism (72) but to the connection pipe (58).
In the second compression mechanism (72), the second injection port
(99) is omitted. In the refrigerant circuit (5), the second
compression mechanism (72) of the second compressor (50b)
compresses and discharges low-pressure refrigerant sucked through
the suction pipe (54). The first compression mechanism (71) of the
first compressor (50a) sucks the refrigerant discharged from the
second compressor (50b) and second intermediate-pressure gas
refrigerant flowing into the connection pipe (58) from the second
injection pipe (45) through the suction pipe (53). Further, first
intermediate-pressure gas refrigerant is injected to the first
compression mechanism (71) through the first injection pipe (35).
The first compressor (50a) compresses and discharges the
refrigerant discharged from the second compressor (50b), the second
intermediate-pressure gas refrigerant, and the first
intermediate-pressure gas refrigerant.
[0211] Note that each of the first compression mechanism (71) and
the second compression mechanism (72) of the present variation may
be a rotary fluid machine including a pair of cylinders and a pair
of pistons, or a rotary fluid machine including a plurality of
cylinders and a plurality of pistons.
[0212] The foregoing embodiments have been set forth merely for
purposes of preferred examples in nature, and are not intended to
limit the scope, applications, and use of the invention.
INDUSTRIAL APPLICABILITY
[0213] As described above, the present invention is useful for the
refrigerating apparatus in which the gas injection is performed to
supply intermediate-pressure gas refrigerant to the compressor.
DESCRIPTION OF REFERENCE CHARACTERS
[0214] 1 Air Conditioner (Refrigerating Apparatus) [0215] 5
Refrigerant Circuit [0216] 7 Main Path [0217] 20 Enthalpy Reducing
Unit [0218] 21 Branched Path [0219] 22 Expansion Mechanism [0220]
30 First Heat Exchanger [0221] 33 First Branched Pipe [0222] 34
First Expansion Valve [0223] 35 First Injection Pipe (First
Injection Path) [0224] 36 First Gas-Liquid Separator [0225] 37
First Expansion Valve [0226] 40 Second Heat Exchanger [0227] 43
Second Branched Pipe [0228] 44 Second Expansion Valve [0229] 45
Second Injection Pipe (Second Injection Path) [0230] 46 Second
Gas-Liquid Separator [0231] 47 Second Expansion Valve [0232] 50
Compressor [0233] 65 Drive Shaft [0234] 71 First Compression
Mechanism [0235] 72 Second Compression Mechanism [0236] 85 First
Compression Chamber (Compression Chamber) [0237] 95 Second
Compression Chamber (Compression Chamber)
* * * * *