Title: Expander
Abstract: It is an object of the present invention to reduce the constraint that the density ratio is constant as small as possible, and to obtain high power recovering effect in a wide operation range by using an expander which is operated in accordance with a flowing direction of refrigerant. An expander used in a refrigeration cycle uses carbon dioxide as refrigerant and has a compressor, an outdoor heat exchanger and an indoor heat exchanger. The expander comprises a cylindrical cylinder, a rotor which rotates in the cylinder, a vane which divides an expansion space formed between an inner peripheral surface of the cylinder and an outer peripheral surface of the rotor into a plurality of spaces, and a vane groove provided in the rotor for accommodating the vane therein. The vane groove is provided with a back pressure chamber which pushes the vane against the inner peripheral surface of the cylinder, and the refrigerant in the supercritical state is introduced into the back pressure chamber.
Patent Number: 6,877,340 Issued on 04/12/2005 to Hiwata, et al.
| Inventors:
|
Hiwata; Akira (Kyoto, JP);
Iida; Noboru (Shiga, JP)
|
| Assignee:
|
Matsushita Electric Industrial Co., Ltd. (Kodama, JP)
|
| Appl. No.:
|
657182 |
| Filed:
|
September 9, 2003 |
Foreign Application Priority Data
| Oct 18, 2002[JP] | 2002-303982 |
| Current U.S. Class: |
62/527; 62/498; 62/87; 418/268 |
| Intern'l Class: |
F25B 009//00; F25B 001//00; F25B 041//06; F01C 001//00 |
| Field of Search: |
62/527,498,87,278,510
418/268,23,93
|
References Cited [Referenced By]
U.S. Patent Documents
| 1539728 | May., 1925 | Ensign.
| |
| 4174931 | Nov., 1979 | Ishizuka | 418/259.
|
| 4248575 | Feb., 1981 | Watanabe et al. | 418/93.
|
| 4455129 | Jun., 1984 | Sakitani et al. | 418/82.
|
| 4498853 | Feb., 1985 | Sakamaki et al. | 418/268.
|
| 4516920 | May., 1985 | Shibuya | 418/23.
|
| 5327745 | Jul., 1994 | Gilmour | 62/467.
|
| 6178761 | Jan., 2001 | Karl | 62/159.
|
| 6321564 | Nov., 2001 | Yamanaka et al. | 62/510.
|
| Foreign Patent Documents |
| 1 503 590 | Jul., 1969 | DE.
| |
| 2 261 873 | Jun., 1974 | DE.
| |
| 25 44 232 | Jul., 1976 | DE.
| |
| 2544232 | Jul., 1976 | DE | .
|
| 57-108555 | Jul., 1982 | JP.
| |
| 62-77562 | Apr., 1987 | JP.
| |
| 10-19401 | Jan., 1998 | JP.
| |
| 2001066006 | Mar., 2001 | JP | .
|
| 2001-108257 | Apr., 2001 | JP.
| |
| 2001-207983 | Aug., 2001 | JP.
| |
| WO 99/02862 | Jan., 1999 | WO.
| |
| 99/02862 | Jan., 1999 | WO.
| |
| 02/18848 | Mar., 2002 | WO.
| |
Other References
Robinson et al., "Efficiencies of transcritical CO.sub.2 cycles with and
without an expansion turbine", Int. J. Refrig., vol. 21, No. 7, pp.
577-589, 1998.
Douglas M. Robinson et al. "Efficiencies of transcritical CO.sub.2 cycles
with and without an expansion turbine"; International Journal of
Refrigeration, vol. 21, No. 7, Nov. 1998 (pp. 577-589).
|
Primary Examiner: Jiang; Chen Wen
Attorney, Agent or Firm: Armstrong, Kratz, Quintos, Hanson & Brooks, LLP
Claims
What is claimed is:
1. An expander used in a refrigeration cycle using carbon dioxide as
refrigerant and having a compressor, an outdoor heat exchanger and an
indoor heat exchanger, wherein said expander comprises a cylindrical
cylinder, a rotor which rotates in said cylinder, a vane which divides an
expansion space formed between an inner peripheral surface of said
cylinder and an outer peripheral surface of said rotor into a plurality of
spaces, and a vane groove provided in said rotor for accommodating said
vane therein, and wherein said vane groove is provided with a back
pressure chamber which pushes said vane against the inner peripheral
surface of said cylinder, and said refrigerant in the supercritical state
is introduced into said back pressure chamber, wherein the expander is
lubricated by oil mist discharged from the compressor.
2. An expander according to claim 1, further comprising a suction pipe
which introduces refrigerant into said expansion space, wherein a portion
of refrigerant flowing through said suction pipe is introduced into said
back pressure chamber.
3. An expander according to claim 1, wherein no oil reservoir is provided
in a hausing which includes said cylinder or said rotor therein.
4. A refrigeration cycle apparatus having a refrigeration cycle using
carbon dioxide as refrigerant and having a compressor, an outdoor heat
exchanger, an expander and an indoor heat exchanger, said refrigeration
cycle apparatus including, in said refrigeration cycle, a first four-way
valve to which a discharge side pipe and a suction side pipe of said
compressor are connected, and a second four-way valve to which a
refrigerant-inflow side pipe and a refrigerant-outflow side pipe of said
expander are, connected, wherein using, as said expander, a sliding vane
type expander having a cylindrical cylinder, a rotor which rotates in said
cylinder, a vane which divides an expansion space formed between an inner
peripheral surface of said cylinder and an outer peripheral surface of
said rotor into a plurality of spaces, and a vane groove provided in said
rotor for accommodating said vane therein, refrigerant flowing through a
pipe extending from said second four-way valve to a refrigerant-inflow
port of said expander is introduced into a back surface of said vane,
wherein the expander is lubricated by oil mist discharged from the
compressor.
5. A refrigeration cycle apparatus having a refrigeration cycle using
carbon dioxide as refrigerant and having a compressor, an outdoor heat
exchanger, an expander and an indoor heat exchanger, said refrigeration
cycle apparatus including, in said refrigeration cycle, a first four-way
valve to which a discharge side pipe and a suction side pipe of said
compressor are connected, and a second four-way valve to which a
refrigerant-inflow side pipe and a refrigerant-outflow side pipe of said
expander are connected, wherein using, as said expander, a sliding vane
type expander having a cylindrical cylinder, a rotor which rotates in said
cylinder, a vane which divides an expansion space formed between an inner
peripheral surface of said cylinder and an outer peripheral surface of
said rotor into a plurality of spaces, and a vane groove provided in said
rotor for accommodating said vane therein, refrigerant flowing through a
pipe extending from a discharge port of said compressor to said first
four-way valve is introduced into a back surface of said vane, wherein the
expander is lubricated by oil mist discharged from the compressor.
6. A compressor used in a refrigeration cycle using carbon dioxide as
refrigerant and having an outdoor heat exchanger and an indoor heat
exchanger and an expander, wherein said compressor comprises a cylindrical
cylinder, a rotor which rotates in sail cylinder, a vane which divides a
compression space formed between an inner peripheral surface of said
cylinder and an outer peripheral surface of said rotor into a plurality of
spaces, and a vane groove provided in said rotor for accommodating said
vane therein, and wherein said vane groove is provided with a back
pressure chamber which pushes said vane against the inner peripheral
surface of said cylinder, and said refrigerant in the supercritical state
is introduced into said back pressure chamber, wherein the expander is
lubricated by oil mist discharged from the compressor.
7. A compressor according to claim 6, further comprising a discharge pipe
which discharges refrigerant from said compression space, wherein a
portion of refrigerant flowing through said discharge pipe is introduced
into said back pressure chamber.
Description
TECHNICAL FIELD
The present invention relates to an expander used in a refrigeration cycle
using carbon dioxide as refrigerant and having a compressor, an outdoor
heat exchanger and an indoor heat exchanger.
BACKGROUND TECHNIQUE
In recent years, attention is focused on a refrigeration cycle apparatus
using, as refrigerant, carbon dioxide (CO.sub.2, hereinafter) in which
ozone destroy coefficient is zero and global warming coefficient is
extremely smaller than Freon.
There is proposed a refrigeration cycle apparatus using CO.sub.2
refrigerant in which expansion energy of a working medium is recovered
using an expander instead of an expansion valve, thereby enhancing
coefficient of performance of the refrigeration cycle apparatus. It is
proposed to use a swash plate expander as this expander (see patent
document 1 for example).
[Patent Document 1]
Japanese Patent Application Laid-open No.2001-141315 (FIG. 2)
In the present invention, a sliding vane type expander is employed as the
expander. In the sliding vane type expander, since the vane jumps, a large
sound is generated and a hitch is generated in a tip end of the vane. If a
back pressure is insufficient, a leakage from the tip end of the vane is
increased, and a leakage loss is generated.
Such problems are solved if lubricant discharged into a high pressure
chamber is supplied to a back surface of the vane, but a structure for
supplying the lubricant becomes complicated.
If a spring is disposed in a back surface of the vane, a reliability
between contact surfaces of the spring and the vane is deteriorated, and
if high pressure refrigerant gas is supplied, since the refrigerant is
gas, the leakage loss is adversely increased.
It is an object of the present invention to provide an expander in which
its structure is simple, the leakage loss is small and the expander is
operated reliably, by utilizing refrigerant in the supercritical state.
SUMMARY OF THE INVENTION
A first aspect of the invention provides an expander used in a
refrigeration cycle using carbon dioxide as refrigerant and having a
compressor, an outdoor heat exchanger and an indoor heat exchanger,
wherein the expander comprises a cylindrical cylinder, a rotor which
rotates in the cylinder, a vane which divides an expansion space formed
between an inner peripheral surface of the cylinder and an outer
peripheral surface of the rotor into a plurality of spaces, and a vane
groove provided in the rotor for accommodating the vane therein, and
wherein the vane groove is provided with a back pressure chamber which
pushes the vane against the inner peripheral surface of the cylinder, and
the refrigerant in the supercritical state is introduced into the back
pressure chamber.
According to this aspect, by introducing the refrigerant in the
supercritical state, since the refrigerant is not in the gas state, it is
possible to reduce the leakage of refrigerant from a gap between a vane
groove and a vane.
According to a second aspect of the invention, in the expander of the first
aspect, the expander further comprises a suction pipe which introduces
refrigerant into the expansion space, and a portion of refrigerant flowing
through the suction pipe is introduced into the back pressure chamber.
Since it is unnecessary to separately introduce refrigerant from outside
of the expander, the mechanism can be simplified.
According to a third aspect of the invention an invention, in the expander
of the first aspect, no oil reservoir is provided in a hausing which
includes the cylinder or the rotor therein. By utilizing the oil mist
discharged from the compressor for lubricating the expander, it is
possible to form a refrigeration cycle apparatus in which a plurality of
oil reservoirs do not exist, and it is possible to avoid a problem that
oil level in each of the plurality of oil reservoirs must be controlled.
A fourth aspect of the invention provides a refrigeration cycle apparatus
having a refrigeration cycle using carbon dioxide as refrigerant and
having a compressor, an outdoor heat exchanger, an expander and an indoor
heat exchanger, the refrigeration cycle apparatus including, in the
refrigeration cycle, a first four-way valve to which a discharge side pipe
and a suction side pipe of the compressor are connected, and a second
four-way valve to which a refrigerant-inflow side pipe and a
refrigerant-outflow side pipe of the expander are connected, wherein
using, as the expander, a sliding vane type expander having a cylindrical
cylinder, a rotor which rotates in the cylinder, a vane which divides an
expansion space formed between an inner peripheral surface of the cylinder
and an outer peripheral surface of the rotor into a plurality of spaces,
and a vane groove provided in the rotor for accommodating the vane
therein, refrigerant flowing through a pipe extending from the second
four-way valve to a refrigerant-inflow port of the expander is introduced
into a back surface of the vane.
A fifth aspect of the invention provides a refrigeration cycle apparatus
having a refrigeration cycle using carbon dioxide as refrigerant and
having a compressor, an outdoor heat exchanger, an expander and an indoor
heat exchanger, the refrigeration cycle apparatus including, in the
refrigeration cycle, a first four-way valve to which a discharge side pipe
and a suction side pipe of the compressor are connected, and a second
four-way valve to which a refrigerant-inflow side pipe and a
refrigerant-outflow side pipe of the expander are connected, wherein
using, as the expander, a sliding vane type expander having a cylindrical
cylinder, a rotor which rotates in the cylinder, a vane which divides an
expansion space formed between an inner peripheral surface of the cylinder
and an outer peripheral surface of the rotor into a plurality of spaces,
and a vane groove provided in the rotor for accommodating the vane
therein, refrigerant flowing through a pipe extending from a discharge
port of the compressor to the first four-way valve is introduced into a
back surface of the vane.
According to the fourth and fifth aspects, by introducing the refrigerant
in the supercritical state, since the refrigerant is not in the gas state,
it is possible to reduce the leakage of refrigerant from a gap between a
vane groove and a vane, and the refrigeration cycle apparatus can be
applied to a cooling and heating air conditioner.
According to a sixth aspect of the invention, in the refrigeration cycle
apparatus of fourth or fifth aspect, the expander is lubricated by oil
mist discharged from the compressor. It is possible to form a
refrigeration cycle apparatus in which a plurality of oil reservoirs do
not exist, and it is possible to avoid a problem that oil level in each of
the plurality of oil reservoirs must be controlled.
A seventh aspect of the invention provides a compressor used in a
refrigeration cycle using carbon dioxide as refrigerant and having an
outdoor heat exchanger and an indoor heat exchanger, wherein the
compressor comprises a cylindrical cylinder, a rotor which rotates in the
cylinder, a vane which divides a compression space formed between an inner
peripheral surface of the cylinder and an outer peripheral surface of the
rotor into a plurality of spaces, and a vane groove provided in the rotor
for accommodating the vane therein, and wherein the vane groove is
provided with a back pressure chamber which pushes the vane against the
inner peripheral surface of the cylinder, and the refrigerant in the
supercritical state is introduced into the back pressure chamber.
According to the seventh aspect, by introducing the refrigerant in the
supercritical state, since the refrigerant is not in the gas state, it is
possible to reduce the leakage of refrigerant from a gap between a vane
groove and a vane.
According to an eighth aspect of the invention, in the compressor of the
seventh aspect, the compressor further comprises a discharge pipe which
discharges refrigerant from the compression space, wherein a portion of
refrigerant flowing through the discharge pipe is introduced into the back
pressure chamber. Since it is unnecessary to separately introduce
refrigerant from outside of the compressor, the mechanism can be
simplified.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side sectional view of an expander according to an embodiment
of the present invention.
FIG. 2 shows a structure of an expanding portion of the expander.
FIG. 3 shows a structure of a heat pump type cooling and heating air
conditioner of the embodiment.
FIG. 4 shows a structure of a heat pump type cooling and heating air
conditioner of another embodiment of the invention.
FIG. 5 shows a structure of a heat pump type cooling and heating air
conditioner of another embodiment of the invention.
FIG. 6 shows a structure of a heat pump type cooling and heating air
conditioner of another embodiment of the invention.
PREFERRED EMBODIMENTS
An expander according to an embodiment of the present invention will be
explained below with reference to the drawings.
FIG. 1 is a side sectional view of the expander of this embodiment. FIG. 2
shows a structure of an expanding portion of the expander.
The expander 6 of this embodiment is a sliding vane type expander. The
sliding vane type expander has a hausing 60, and the hausing 60 is
provided therein with a cylindrical cylinder 61 and a columnar rotor 62
which rotates in the cylinder 61. The cylinder 61 and the rotor 62 are
sandwiched from their both sides by two side plates 63, and an expansion
space are formed therebetween. Each of the side plates 63 is provided at
its central portion with a bearing 64. A rotation shaft 65 is rotatably
held by the bearing 64. Rotation of the rotor 62 is output to outside by
this rotation shaft 65. A high pressure seal 66 is provided between the
rotation shaft 65 and a hausing 60. A side seal 67 is provided between the
side plate 63 and the rotor 62.
The rotor 62 includes a plurality of vane grooves 68. A vane 69 is slidably
disposed in the vane groove 68. A back pressure chamber 68a is formed in
the vane groove 68 at a location closer to a center of the rotor 62. The
vane 69 is pushed against an inner peripheral surface of the cylinder 61
by a pressure of the back pressure chamber 68a.
The cylinder 61 is provided with a suction pipe 70 and a discharge pipe 71.
The suction pipe 70 and the discharge pipe 71 are in communication with
the expansion space.
A ring-like fluid supply groove 72 is formed in a contact surface of the
side plate 63 with respect to the rotor 62. The fluid supply groove 72 is
formed at a location where the fluid supply groove 72 is always in
communication with the back pressure chamber 68a. The fluid supply groove
72 is in communication with the back pressure chamber 68a through the
fluid supply hole 74 and the fluid supply pipe 73 which introduce
refrigerant in a supercritical state from outside.
The operation of the expander of this embodiment will be explained below.
In FIG. 2, high pressure refrigerant in the supercritical state introduced
from the suction pipe 70 enters into the expansion space formed between
the inner peripheral surface of the cylinder 61 and an outer peripheral
surface of the rotor 62, and is expanded while rotating the rotor 62 in a
counterclockwise direction, and is discharged from the discharge pipe 71.
High pressure refrigerant in the supercritical state introduced from the
fluid supply hole 74 is introduced into the fluid supply groove 72 through
the fluid supply hole 74. The high pressure refrigerant introduced into
the fluid supply groove 72 is introduced into the back pressure chamber
68a and functions to push the vane 69 against the inner peripheral surface
of the cylinder 61.
Since the refrigerant in the supercritical state is introduced into the
back pressure chamber 68a in this manner, it is possible to reduce the
leakage of refrigerant from a gap between the vane groove 68 and the vane
69 as compared with refrigerant in a gas state, and it is possible to
reliably push the vane against the inner peripheral surface of the
cylinder 61.
Although this embodiment has been explained using the fluid supply hole 74
which introduces the refrigerant in the supercritical state from outside,
a communication path which introduces a portion of refrigerant of the
suction pipe 70 into the fluid supply groove 72 may be formed in the side
plate without using the fluid supply hole 74. If a portion of refrigerant
flowing through the suction pipe 70 is introduced into the back pressure
chamber 68a in this manner, since it is unnecessary to separately
introduce refrigerant from outside of the expander 6, it is possible to
simplify the mechanism.
A refrigeration cycle apparatus using an expander according to the
embodiment of the present invention will be explained with reference to
the drawing based on a heat pump type cooling and heating air conditioner.
FIG. 3 shows a structure of the heat pump type cooling and heating air
conditioner of this embodiment.
As shown in FIG. 3, the heat pump type cooling and heating air conditioner
of this embodiment uses a CO.sub.2 refrigerant as refrigerant, and
comprises a refrigerant circuit in which a compressor 1 having a motor 11,
an outdoor heat exchanger 3, an expander 6 and an indoor heat exchanger 8
are connected to one another through pipes.
The expander 6 is provided at its inflow side pipe with a pre-expansion
valve 5.
A bypass circuit which bypasses the pre-expansion valve 5 and the expander
6 is provided in parallel to the pre-expansion valve 5 and the expander 6.
The bypass circuit is provided with a control valve 7.
A drive shaft of the expander 6 and a drive shaft of the compressor 1 are
connected to each other, and the compressor 1 utilizes power recover by
the expander 6 for driving.
The refrigerant circuit is provided with a first four-way valve 2 to which
a discharge side pipe and a suction side pipe of the compressor 1 are
connected, and a second four-way valve 4 to which a refrigerant-inflow
side pipe of the pre-expansion valve 5, a refrigerant-outflow side pipe of
the expander 6 and the bypass circuit are connected.
The fluid supply pipe 73 introduces refrigerant which flows through a pipe
extending from the second four-way valve 4 to the refrigerant-inflow port
of the expander 6. It is preferable that the fluid supply pipe 73 is
connected to the inflow side pipe of the pre-expansion valve 5.
The operation of the heat pump type cooling and heating air conditioner of
this embodiment will be explained.
First, a cooling operation mode in which the outdoor heat exchanger 3 is
used as a gas cooler and the indoor heat exchanger 8 is used as an
evaporator will be explained. A flow of the refrigerant in the cooling
operation mode is shown with solid arrows in the drawing.
Refrigerant at the time of the cooling operation mode is compressed at a
high temperature and under a high pressure and is discharged by the
compressor 1 which is driven by the motor 11. The refrigerant is
introduced into the outdoor heat exchanger 3 through the first four-way
valve 2. In the outdoor heat exchanger 3, since CO.sub.2 refrigerant is in
a supercritical state, the refrigerant is not brought into two-phase
state, and dissipates heat to outside fluid such as air and water. Then,
the CO.sub.2 refrigerant is introduced into the pre-expansion valve 5 and
the expander 6 through the second four-way valve 4, and is expanded by the
pre-expansion valve 5 and the expander 6. Power recover by the expander 6
at the time of expanding operation is used for driving the compressor 1.
At that time, the opening of the control valve 7 is adjusted in accordance
with a high pressure detected at an outlet of the outdoor heat exchanger
3, thereby controlling an amount of refrigerant which is allowed to flow
into the bypass circuit. The opening of the pre-expansion valve 5 is
adjusted in accordance with the detected high pressure, thereby
controlling an amount of refrigerant which is allowed to flow into the
expander 6.
The CO.sub.2 refrigerant expanded by the pre-expansion valve 5 and the
expander 6 is introduced into the indoor heat exchanger 8 through the
second four-way valve 4 and is evaporated and suctions heat in the indoor
heat exchanger 8. A room is cooled by this endotherm. The refrigerant
which has been evaporated is drawn into compressor 1.
Next, a heating operation mode in which the outdoor heat exchanger 3 is
used as the evaporator and the indoor heat exchanger 8 is used as the gas
cooler will be explained. A flow of a refrigerant in this heating
operation mode is shown with dashed arrows in the drawing.
Refrigerant at the time of the heating operation mode is compressed at a
high temperature and under a high pressure and is discharged by the
compressor 1 which is driven by the motor 11. The refrigerant is
introduced into the indoor heat exchanger 8 through the first four-way
valve 2. In the indoor heat exchanger 8, since CO.sub.2 refrigerant is in
a supercritical state, the refrigerant is not brought into two-phase
state, and dissipates heat to outside fluid such as air and water. A room
is heated utilizing this radiation. Then, the CO.sub.2 refrigerant is
introduced into the pre-expansion valve 5 and the expander 6, and is
expanded by the pre-expansion valve 5 and the expander 6. Power recover by
the expander 6 at the time of expanding operation is used for driving the
compressor 1. At that time, the opening of the control valve 7 is adjusted
in accordance with a high pressure detected at an outlet of the indoor
heat exchanger 8, thereby controlling an amount of refrigerant which is
allowed to flow into the bypass circuit. The opening of the pre-expansion
valve 5 is adjusted in accordance with the detected high pressure, thereby
controlling an amount of refrigerant which is allowed to flow into the
expander 6.
The CO.sub.2 refrigerant expanded by the pre-expansion valve 5 and the
expander 6 is introduced into the outdoor heat exchanger 3 through the
second four-way valve 4 and is evaporated and suctions heat in the outdoor
heat exchanger 3. The refrigerant which has been evaporated is drawn into
the compressor 1 through the first four-way valve 2.
High pressure refrigerant in the supercritical state is introduced into the
back pressure chamber 68a in the expander 6 by the fluid supply pipe 73,
and the high pressure refrigerant reliably pushes the vane 69 against the
inner peripheral surface of the cylinder 61.
In this embodiment, the fluid supply pipe 73 introduces the refrigerant
which flows through the pipe extending from the second four-way valve 4 to
the refrigerant-inflow port of the expander 6, but the fluid supply pipe
73 may introduces refrigerant which flows through a pipe extending from a
discharge port of the compressor 1 to the first four-way valve 2.
A refrigeration cycle apparatus using an expander according to the
embodiment of the present invention will be explained with reference to
the drawing based on a heat pump type cooling and heating air conditioner
of another embodiment.
FIG. 4 shows a structure of the heat pump type cooling and heating air
conditioner of this embodiment.
As shown in FIG. 4, the heat pump type cooling and heating air conditioner
of this embodiment uses a CO.sub.2 refrigerant as refrigerant, and
comprises a refrigerant circuit in which a compressor 1 having a motor 11,
an outdoor heat exchanger 3, an expander 6, an indoor heat exchanger 8 and
an auxiliary compressor 10 are connected to one another through pipes.
The expander 6 is provided at its inflow side pipe with a pre-expansion
valve 5.
A bypass circuit which bypasses the pre-expansion valve 5 and the expander
6 is provided in parallel to the pre-expansion valve 5 and the expander 6.
The bypass circuit is provided with a control valve 7.
A drive shaft of the expander 6 and a drive shaft of the auxiliary
compressor 10 are connected to each other, and the auxiliary compressor 10
is driven by power recover by the expander 6.
The refrigerant circuit is provided with a first four-way valve 2 to which
a discharge side pipe of the compressor 1 and a suction side pipe of the
auxiliary compressor 10 are connected, and a second four-way valve 4 to
which a refrigerant-inflow side pipe of the pre-expansion valve 5, a
refrigerant-outflow side pipe of the expander 6 and the bypass circuit are
connected.
The fluid supply pipe 73 introduces refrigerant which flows through a pipe
extending from the second four-way valve 4 to the refrigerant-inflow port
of the expander 6. It is preferable that the fluid supply pipe 73 is
connected to the inflow side pipe of the pre-expansion valve 5.
The operation of the heat pump type cooling and heating air conditioner of
this embodiment will be explained.
First, a cooling operation mode in which the outdoor heat exchanger 3 is
used as a gas cooler and the indoor heat exchanger 8 is used as an
evaporator will be explained. A flow of the refrigerant in the cooling
operation mode is shown with solid arrows in the drawing.
Refrigerant at the time of the cooling operation mode is compressed at a
high temperature and under a high pressure and is discharged by the
compressor 1 which is driven by the motor 11. The refrigerant is
introduced into the outdoor heat exchanger 3 through the first four-way
valve 2. In the outdoor heat exchanger 3, since CO.sub.2 refrigerant is in
a supercritical state, the refrigerant is not brought into two-phase
state, and dissipates heat to outside fluid such as air and water. Then,
the CO.sub.2 refrigerant is introduced into the pre-expansion valve 5 and
the expander 6, and is expanded by the pre-expansion valve 5 and the
expander 6. Power recover by the expander 6 at the time of expanding
operation is used for driving the auxiliary compressor 10. At that time,
the opening of the control valve 7 is adjusted in accordance with a high
pressure detected at an outlet of the outdoor heat exchanger 3, thereby
controlling an amount of refrigerant which is allowed to flow into the
bypass valve. The opening of the pre-expansion valve 5 is adjusted in
accordance with the detected high pressure, thereby controlling an amount
of refrigerant which is allowed to flow into the expander 6.
The CO.sub.2 refrigerant expanded by the pre-expansion valve 5 and the
expander 6 is introduced into the indoor heat exchanger 8 through the
second four-way valve 4 and is evaporated and suctions heat in the indoor
heat exchanger 8. A room is cooled by this endotherm. The refrigerant
which has been evaporated is introduced into the auxiliary compressor 10
through the first four-way valve 2 and supercharged by the auxiliary
compressor 10 and is drawn into compressor 1.
Next, a heating operation mode in which the outdoor heat exchanger 3 is
used as the evaporator and the indoor heat exchanger 8 is used as the gas
cooler will be explained. A flow of a refrigerant in this heating
operation mode is shown with dashed arrows in the drawing.
Refrigerant at the time of the heating operation mode is compressed at a
high temperature and under a high pressure and is discharged by the
compressor 1 which is driven by the motor 11. The refrigerant is
introduced into the indoor heat exchanger 8 through the first four-way
valve 2. In the indoor heat exchanger 8, since CO.sub.2 refrigerant is in
a supercritical state, the refrigerant is not brought into two-phase
state, and dissipates heat to outside fluid such as air and water. A room
is heated utilizing this radiation. Then, the CO.sub.2 refrigerant is
introduced into the pre-expansion valve 5 and the expander 6, and is
expanded by the pre-expansion valve 5 and the expander 6. Power recover by
the expander 6 at the time of expanding operation is used for driving the
auxiliary compressor 10. At that time, the opening of the control valve 7
is adjusted in accordance with a high pressure detected at an outlet of
the indoor heat exchanger 8, thereby controlling an amount of refrigerant
which is allowed to flow into the bypass valve. The opening of the
pre-expansion valve 5 is adjusted in accordance with the detected high
pressure, thereby controlling an amount of refrigerant which is allowed to
flow into the expander 6.
The CO.sub.2 refrigerant expanded by the pre-expansion valve 5 and the
expander 6 is introduced into the outdoor heat exchanger 3 through the
second four-way valve 4 and is evaporated and suctions heat in the outdoor
heat exchanger 3. The refrigerant which has been evaporated is introduced
into the auxiliary compressor 10 through the first four-way valve 2 and
supercharged by the auxiliary compressor 10 and drawn into the compressor
1.
High pressure refrigerant in the supercritical state is introduced into the
back pressure chamber 68a in the expander 6 by the fluid supply pipe 73,
and the high pressure refrigerant reliably pushes the vane 69 against the
inner peripheral surface of the cylinder 61.
In this embodiment, the fluid supply pipe 73 introduces the refrigerant
which flows through the pipe extending from the second four-way valve 4 to
the refrigerant-inflow port of the expander 6, but the fluid supply pipe
73 may introduces refrigerant which flows through a pipe extending from a
discharge port of the compressor 1 to the first four-way valve 2.
A refrigeration cycle apparatus using an expander according to the
embodiment of the present invention will be explained with reference to
the drawing based on a heat pump type cooling and heating air conditioner
of another embodiment.
FIG. 5 shows a structure of the heat pump type cooling and heating air
conditioner of this embodiment.
As shown in FIG. 5, the heat pump type cooling and heating air conditioner
of this embodiment uses a CO.sub.2 refrigerant as refrigerant, and
comprises a refrigerant circuit in which a compressor 1 having a motor 11,
an auxiliary compressor 10, an outdoor heat exchanger 3, an expander 6 and
an indoor heat exchanger 8 are connected to one another through pipes.
The expander 6 is provided at its inflow side pipe with a pre-expansion
valve 5.
A bypass circuit which bypasses the pre-expansion valve 5 and the expander
6 is provided in parallel to the pre-expansion valve 5 and the expander 6.
The bypass circuit is provided with a control valve 7.
A drive shaft of the expander 6 and a drive shaft of the auxiliary
compressor 10 are connected to each other, and the auxiliary compressor 10
is driven by power recover by the expander 6.
The refrigerant circuit is provided with a first four-way valve 2 to which
a suction side pipe of the compressor 1 and a discharge side pipe of the
auxiliary compressor 10 are connected, and a second four-way valve 4 to
which a suction side pipe of the pre-expansion valve 5, a discharge side
pipe of the expander 6 and the bypass circuit are connected.
The fluid supply pipe 73 introduces refrigerant which flows through a pipe
extending from the second four-way valve 4 to the refrigerant-inflow port
of the expander 6. It is preferable that the fluid supply pipe 73 is
connected to the inflow side pipe of the pre-expansion valve 5.
The operation of the heat pump type cooling and heating air conditioner of
this embodiment will be explained.
First, a cooling operation mode in which the outdoor heat exchanger 3 is
used as a gas cooler and the indoor heat exchanger 8 is used as an
evaporator will be explained. A flow of the refrigerant in the cooling
operation mode is shown with solid arrows in the drawing.
Refrigerant at the time of the cooling operation mode is compressed at a
high temperature and under a high pressure and is discharged by the
compressor 1 which is driven by the motor 11. The refrigerant is
introduced into the auxiliary compressor 10 and super-pressurized by the
auxiliary compressor 10 and then, is introduced into the outdoor heat
exchanger 3 through the first four-way valve 2. In the outdoor heat
exchanger 3, since CO.sub.2 refrigerant is in a supercritical state, the
refrigerant is not brought into two-phase state, and dissipates heat to
outside fluid such as air and water. Then, the CO.sub.2 refrigerant is
introduced into the pre-expansion valve 5 and the expander 6, and is
expanded by the pre-expansion valve 5 and the expander 6. Power recover by
the expander 6 at the time of expanding operation is used for driving the
auxiliary compressor 10. At that time, the opening of the control valve 7
is adjusted in accordance with a high pressure detected at an outlet of
the outdoor heat exchanger 3, thereby controlling an amount of refrigerant
which is allowed to flow into the bypass valve. The opening of the
pre-expansion valve 5 is adjusted in accordance with the detected high
pressure, thereby controlling an amount of refrigerant which is allowed to
flow into the expander 6.
The CO.sub.2 refrigerant expanded by the pre-expansion valve 5 and the
expander 6 is introduced into the indoor heat exchanger 8 through the
second four-way valve 4 and is evaporated and suctions heat in the indoor
heat exchanger 8. A room is cooled by this endotherm. The refrigerant
which has been evaporated is drawn into compressor 1 through the first
four-way valve 2.
Next, a heating operation mode in which the outdoor heat exchanger 3 is
used as the evaporator and the indoor heat exchanger 8 is used as the gas
cooler will be explained. A flow of a refrigerant in this heating
operation mode is shown with dashed arrows in the drawing.
Refrigerant at the time of the heating operation mode is compressed at a
high temperature and under a high pressure and is discharged by the
compressor 1 which is driven by the motor 11. The refrigerant is
introduced into the auxiliary compressor 10 and super-pressurized by the
auxiliary compressor 10 and then, is introduced into the indoor heat
exchanger 8 through the first four-way valve 2. In the indoor heat
exchanger 8, since CO.sub.2 refrigerant is in a supercritical state, the
refrigerant is not brought into two-phase state, and dissipates heat to
outside fluid such as air and water. A room is heated utilizing this
radiation. Then, the CO.sub.2 refrigerant is introduced into the
pre-expansion valve 5 and the expander 6, and is expanded by the
pre-expansion valve 5 and the expander 6. Power recover by the expander 6
at the time of expanding operation is used for driving the auxiliary
compressor 10. At that time, the opening of the control valve 7 is
adjusted in accordance with a high pressure detected at an outlet of the
indoor heat exchanger 8, thereby controlling an amount of refrigerant
which is allowed to flow into the bypass circuit. The opening of the
pre-expansion valve 5 is adjusted in accordance with the detected high
pressure, thereby controlling an amount of refrigerant which is allowed to
flow into the expander 6.
The CO.sub.2 refrigerant expanded by the pre-expansion valve 5 and the
expander 6 is introduced into the outdoor heat exchanger 3 through the
second four-way valve 4 and is evaporated and suctions heat in the outdoor
heat exchanger 3. The refrigerant which has been evaporated is drawn into
the compressor 1 through the first four-way valve 2.
High pressure refrigerant in the supercritical state is introduced into the
back pressure chamber 68a in the expander 6 by the fluid supply pipe 73,
and the high pressure refrigerant reliably pushes the vane 69 against the
inner peripheral surface of the cylinder 61.
In this embodiment, the fluid supply pipe 73 introduces the refrigerant
which flows through the pipe extending from the second four-way valve 4 to
the refrigerant-inflow port of the expander 6, but the fluid supply pipe
73 may introduces refrigerant which flows through pipe extending from a
discharge port of the compressor 1 to the first four-way valve 2.
A refrigeration cycle apparatus using an expander according to the
embodiment of the present invention will be explained with reference to
the drawing based on a heat pump type cooling and heating air conditioner
of another embodiment.
FIG. 6 shows a structure of the heat pump type cooling and heating air
conditioner of this embodiment.
As shown in FIG. 6, the heat pump type cooling and heating air conditioner
of this embodiment uses a CO.sub.2 refrigerant as refrigerant, and
comprises a refrigerant circuit in which a compressor 1 having a motor 11,
an outdoor heat exchanger 3, an expander 6, an indoor heat exchanger 8 and
an auxiliary compressor 10 are connected to one another through pipes.
The refrigerant circuit comprises a first four-way valve 2 to which a
discharge side pipe and a suction side pipe of the compressor 1 are
connected, a second four-way valve 4 to which a discharge side pipe and a
suction side pipe of the expander 6 are connected, and a third four-way
valve 9 to which a discharge side pipe and a suction side pipe of the
auxiliary compressor 10 are connected. In the case of refrigerant flow in
which the outdoor heat exchanger 3 is used as a gas cooler and the indoor
heat exchanger 8 is used as an evaporator, the first four-way valve 2 and
the third four-way valve 9 are switched over so that the discharge side of
the auxiliary compressor 10 becomes the suction side of the compressor 1.
In the case of refrigerant flow in which the outdoor heat exchanger 3 is
used as the evaporator and the indoor heat exchanger 8 is used as the gas
cooler, the first four-way valve 2 and the third four-way valve 9 are
switched over so that the discharge side of the compressor 1 becomes the
suction side of the auxiliary compressor 10. By switching the second
four-way valve 4, a direction of the refrigerant flowing through the
expander 6 becomes always the same direction.
The expander 6 is provided at its inflow side with a pre-expansion valve 5
capable of changing the opening of the valve.
A bypass circuit which bypasses the pre-expansion valve 5 and the expander
6 is provided. The bypass circuit is provided with a bypass valve 7 which
adjusts a flow rate of refrigerant of the bypass circuit.
A drive shaft of the expander 6 and a drive shaft of the auxiliary
compressor 10 are connected to each other, and the auxiliary compressor 10
is driven by power recover by the expander 6.
The fluid supply pipe 73 introduces refrigerant which flows through a pipe
extending from the second four-way valve 4 to the refrigerant-inflow port
of the expander 6. It is preferable that the fluid supply pipe 73 is
connected to the inflow side pipe of the pre-expansion valve 5.
The operation of the heat pump type cooling and heating air conditioner of
this embodiment will be explained.
First, a cooling operation mode in which the outdoor heat exchanger 3 is
used as a gas cooler and the indoor heat exchanger 8 is used as an
evaporator will be explained. A flow of the refrigerant in the cooling
operation mode is shown with solid arrows in the drawing.
Refrigerant at the time of the cooling operation mode is compressed at a
high temperature and under a high pressure and is discharged by the
compressor 1 which is driven by the motor 11. The refrigerant is
introduced into the outdoor heat exchanger 3 through the first four-way
valve 2. In the outdoor heat exchanger 3, since CO.sub.2 refrigerant is in
a supercritical state, the refrigerant is not brought into two-phase
state, and dissipates heat to outside fluid such as air and water. Then,
the CO.sub.2 refrigerant is introduced into the second four-way valve 4,
the pre-expansion valve 5 and the expander 6, and is expanded by the
expander 6. At that time, an optimal amount of refrigerant flowing into
the expander 6 is calculated from a high pressure refrigerant temperature
and a high pressure refrigerant pressure detected on the side of the
outlet of the outdoor heat exchanger 3. The opening of the pre-expansion
valve 5 or the bypass valve 7 is adjusted such that if the volume flow
rate is greater than the calculated optimal refrigerant amount, the
opening of the bypass valve 7 is increased to reduce the volume flow rate
of refrigerant flowing into the expander 6, and if the volume flow rate is
smaller than the calculated optimal refrigerant amount, the opening of the
pre-expansion valve 5 is reduced to increase the volume flow rate. The
expanded CO.sub.2 refrigerant is evaporated and suctions heat in the
indoor heat exchanger 8 through the second four-way valve 4. A room is
cooled by this endotherm. The refrigerant which has been evaporated is
introduced into the auxiliary compressor 10 through the third four-way
valve 9 and supercharged by the auxiliary compressor 10, and is drawn into
the compressor 1 through the third four-way valve 9 and the first four-way
valve 2. Energy generated when expansion is carried out in the expander 6
is utilized for this supercharging operation of the auxiliary compressor
10, and power is recovered.
Next, a heating operation mode in which the outdoor heat exchanger 3 is
used as the evaporator and the indoor heat exchanger 8 is used as the gas
cooler will be explained. A flow of a refrigerant in this heating
operation mode is shown with dashed arrows in the drawing.
Refrigerant at the time of the heating operation mode is compressed at a
high temperature and under a high pressure and is discharged by the
compressor 1 which is driven by the motor 11. The refrigerant is
introduced into the auxiliary compressor 10 through the first four-way
valve 2 and the third four-way valve 9, and further super-pressurized by
the auxiliary compressor 10. The expansion energy at the expander 6 is
utilized for this super-pressurizing operation and power into the indoor
heat exchanger 8 through the third four-way valve 9. In the indoor heat
exchanger 8, since CO.sub.2 refrigerant is in a supercritical state, the
refrigerant is not brought into two-phase state, and dissipates heat to
outside fluid such as air and water. Then, the CO.sub.2 refrigerant is
introduced into the expander 6 through the second four-way valve 4 and the
pre-expansion valve 5, and is expanded by the expander 6. At that time, an
optimal amount of refrigerant flowing into the expander 6 is calculated
from a high pressure refrigerant temperature and a high pressure
refrigerant pressure detected on the side of the outlet of the indoor heat
exchanger 8. The opening of the pre-expansion valve 5 or the bypass valve
7 is adjusted such that if the volume flow rate is greater than the
calculated optimal refrigerant amount, the opening of the bypass valve 7
is increased to reduce the volume flow rate of refrigerant flowing into
the expander 6, and if the volume flow rate is smaller than the calculated
optimal refrigerant amount, the opening of the pre-expansion valve 5 is
reduced to increase the volume flow rate. The expanded CO.sub.2
refrigerant is evaporated and suctions heat in the outdoor heat exchanger
3 through the second four-way valve 4. The refrigerant which has been
evaporated is drawn into the compressor 1 through the first four-way valve
2.
High pressure refrigerant in the supercritical state is introduced into the
back pressure chamber 68a in the expander 6 by the fluid supply pipe 73,
and the high pressure refrigerant reliably pushes the vane 69 against the
inner peripheral surface of the cylinder 61.
In this embodiment, the fluid supply pipe 73 introduces the refrigerant
which flows through the pipe extending from the second four-way valve 4 to
the refrigerant-inflow port of the expander 6, but the fluid supply pipe
73 may introduces refrigerant which flows through a pipe extending from a
discharge port of the compressor 1 to the first four-way valve 2.
According to this embodiment, the compressor 1 which compresses refrigerant
and the expander 6 and the auxiliary compressor 10 which recover the power
are separated from each other. The refrigeration cycle is switched such
that the refrigerant is supercharged by the auxiliary compressor 10 at the
time of the cooling operation mode, and the refrigerant is
super-pressurized at the time of the heating operation mode. With this
structure, it is possible to allow the expander 6 to operate as a
supercharging type expander which is suitable for cooling, and as a
super-pressurizing type expander which is suitable for heating.
As described above, according to this embodiment, it is possible to provide
an air conditioner capable of efficiently operating the refrigeration
cycle even in a wide operating range, in which power is recovered while
using CO.sub.2 refrigerant as refrigerant.
In each of the embodiments, a sliding vane type expander is used as the
expander 6, no oil reservoir is provided in a hausing 60, and lubrication
in the expander 6 is carried out using oil mist discharged from the
compressor 1. Therefore, it is possible to avoid a problem that oil level
in each of a plurality of oil reservoirs must be controlled. Especially
when the auxiliary compressor 10 and the expander 6 are connected to each
other and the auxiliary compressor 10 supercharges and super-pressurizes
as in the embodiment shown in FIG. 6, since the expander 6 does not have
the oil reservoir, it is possible to integrally form the auxiliary
compressor 10 and the expander 6.
Although the above embodiments have been described using the heat pump type
cooling and heating air conditioner, the present invention can also be
applied to other refrigeration cycle apparatuses in which the outdoor heat
exchanger 3 is used as a first heat exchanger, the indoor heat exchanger 8
is used as a second heat exchanger, and the first and second heat
exchangers are utilized for hot and cool water devices or thermal
storages.
In the embodiments, the drive shaft of the expander 6 is connected to the
drive shaft of the compressor 1 or the auxiliary compressor 10, and power
recover by the expander 6 is utilized for driving the compressor 1 or the
auxiliary compressor 10, but the drive shaft of the expander 6 may be
provided with an electric generator to convert the power into electricity.
The compressor 1 and the auxiliary compressor 10 explained in the above
embodiments can be formed into a sliding vane type compressor explained in
FIG. 1 and FIG. 2. In this case, the expansion space is formed into a
compression space. Especially when the auxiliary compressor 10 is formed
into the sliding vane type compressor, the expander 6 and the auxiliary
compressor 10 can be lubricated only with oil mist discharged from the
compressor 1, and the expander 6 and the auxiliary compressor 10 do not
require a hausing having an oil reservoir.
As described above, according to the present invention, by introducing the
refrigerant in the supercritical state, since the refrigerant is not in
the gas state, it is possible to reduce the leakage of refrigerant from a
gap between a vane groove and a vane.
According to the invention, a portion of refrigerant flowing through the
suction pipe is introduced into the back pressure chamber, and since it is
unnecessary to separately introduce refrigerant from outside of the
expander, the mechanism can be simplified.
*
