U.S. patent application number 15/538118 was filed with the patent office on 2017-12-07 for refrigeration cycle device and compressor used in same.
The applicant listed for this patent is Panasonic Intellectual Property Management Co., Ltd.. Invention is credited to HIROAKI NAKAI, ATSUSHI SAKUDA.
Application Number | 20170350623 15/538118 |
Document ID | / |
Family ID | 56405357 |
Filed Date | 2017-12-07 |
United States Patent
Application |
20170350623 |
Kind Code |
A1 |
NAKAI; HIROAKI ; et
al. |
December 7, 2017 |
REFRIGERATION CYCLE DEVICE AND COMPRESSOR USED IN SAME
Abstract
A refrigeration cycle device according to the present invention
includes a compressor having a first compression chamber and a
second compression chamber, a condenser, a decompressor, an
evaporator, an injection path configured to introduce intermediate
pressure refrigerant, a communication passage configured to
introduce intermediate pressure refrigerant compressed in the first
compression chamber to the second compression chamber, and a switch
element configured to selectively make the second compression
chamber communicate with the evaporator or make the second
compression chamber communicate with the communication passage. The
injection path introduces the intermediate pressure refrigerant to
the second compression chamber. Single-stage compressing operation
is performed when the second compression chamber is communicated
with the evaporator, and two-stage compressing operation is
performed when the second compression chamber is communicated with
the communication passage.
Inventors: |
NAKAI; HIROAKI; (Shiga,
JP) ; SAKUDA; ATSUSHI; (Shiga, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Panasonic Intellectual Property Management Co., Ltd. |
Osaka |
|
JP |
|
|
Family ID: |
56405357 |
Appl. No.: |
15/538118 |
Filed: |
November 12, 2015 |
PCT Filed: |
November 12, 2015 |
PCT NO: |
PCT/JP2015/005654 |
371 Date: |
June 20, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04C 2240/806 20130101;
Y02B 30/70 20130101; F25B 2400/074 20130101; F25B 2500/31 20130101;
F04C 23/001 20130101; Y02B 30/741 20130101; F25B 2341/0662
20130101; F04C 18/356 20130101; F04C 23/008 20130101; F25B 1/04
20130101; F25B 2600/021 20130101; F04C 29/12 20130101; F25B 1/10
20130101; F25B 2400/23 20130101; F04C 28/02 20130101; F25B 2400/13
20130101; F04C 29/0014 20130101; F04C 23/003 20130101; F25B 49/025
20130101 |
International
Class: |
F25B 1/10 20060101
F25B001/10; F04C 23/00 20060101 F04C023/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 15, 2015 |
JP |
2015-005642 |
Claims
1. A refrigeration cycle device comprising: a compressor including
a first compression chamber and a second compression chamber that
are independent; a condenser; a decompressor; an evaporator; an
injection path configured to introduce intermediate pressure
refrigerant decompressed by the decompressor; a first suction path
configured to introduce low pressure refrigerant from the
evaporator to the first compression chamber; a second suction path
configured to introduce low pressure refrigerant from the
evaporator to the second compression chamber; a communication
passage configured to introduce intermediate pressure refrigerant
compressed in the first compression chamber to the second
compression chamber; and a switch element configured to selectively
make the second compression chamber communicate with the evaporator
or make the second compression chamber communicate with the
communication passage, wherein the injection path introduces the
intermediate pressure refrigerant to the second compression
chamber, the refrigerant is compressed in the first compression
chamber and the second compression chamber independently when the
second compression chamber is communicated with the evaporator, and
refrigerant compressed in the first compression chamber is further
compressed in the second compression chamber when the second
compression chamber is communicated with the communication
passage.
2. The refrigeration cycle device according to claim 1, wherein the
second suction path has a connection part connecting with the
injection path on a downstream side of the switch element.
3. The refrigeration cycle device according to claim 1, wherein a
volume of the first compression chamber and a volume of the second
compression chamber are equal.
4. The refrigeration cycle device according to claim 1, wherein the
compressor is provided around a shaft and has two eccentric shafts
each performing eccentric rotation, and phases of the two eccentric
shafts are deviated by 180 degrees.
5. The refrigeration cycle device according to claim 2, wherein the
second suction path has an upward gradient part between the
connection part and the second compression chamber.
6. The refrigeration cycle device according to claim 1, wherein
inverter operation to arbitrarily change a rotation number of the
compressor is performed.
7. A compressor being the compressor included in the refrigeration
cycle device according to any one of claims 1 to 6.
Description
TECHNICAL FIELD
[0001] The present invention relates to a refrigeration cycle
device and a compressor used in the same.
BACKGROUND ART
[0002] FIG. 6 is a diagram illustrating a refrigeration cycle
configured by compressor 101, condenser 102, evaporator 103,
decompressors 104, injection pipe 105, and gas-liquid separator
106. In the refrigeration cycle, a gas phase component and a liquid
phase component of intermediate pressure refrigerant are separated
by using gas-liquid separator 106 to perform gas injection.
Conventionally, in order to reduce power consumption and improve
capability of the refrigeration cycle, a refrigeration cycle device
has been proposed that injects intermediate pressure gas
refrigerant into a compressor. For example, Patent Literature 1
discloses a rotary compressor equipped with back flow suppressive
means for suppressing back flow of gas refrigerant in a compression
chamber when gas refrigerant that has taken out from gas-liquid
separator 106 is injected in the working compression chamber.
Furthermore, Patent Literature 2 discloses a rotary type two-stage
compressor that performs gas injection with respect to an
intermediate pressure region of two-stage compression.
[0003] However, like Patent Literature 1, when gas injection is
performed with respect to the working compression chamber, the
pressure in the compression chamber is largely fluctuated from low
pressure to high pressure at the cycle of an operation frequency,
causing a problem to be described below. That is, when the pressure
of an injection pipe outlet becomes higher than an injection gas
pressure, the refrigerant in the compression chamber may
disadvantageously flow back from an injection port. To solve the
problem, Patent Literature 1 discloses provisions such as providing
a check valve to prevent back flow, but the check valve can block
original flow of the injection. Furthermore, even when back flow
itself can be suppressed, injection to the compression chamber
whose pressure fluctuates becomes intermittent, so that pulsation
of refrigerant pressure in the injection pipe becomes large,
disadvantageously causing noise or vibration.
[0004] On the other hand, like Patent Literature 2, when injection
is performed in the intermediate pressure region of the two-stage
compression, injection is performed to a stable pressure region,
which solves the above problems, making it possible to perform gas
injection of a continuously stable amount. In the tow-stage
compression system, under the operating condition in which the
pressure difference between low pressure and high pressure is
large, leakage or the like of refrigerant due to the pressure
difference becomes small as compared with a single-stage
compression system, making it possible to exert high efficiency
capability. However, under the operation condition with a low load
in which the pressure difference is small, the two-stage
compression system has a problem in that its efficiency is lowered
as compared with the single-stage compression system due to slide
loss or the like. Furthermore, substantive compressor suction
volume is limited to the volume of the compression chamber on the
side on which low pressure refrigerant is suctioned, requiring grow
in size of the compressor in order to exert a desired refrigerating
or heating capability under low differential pressure operation
conditions in which injection effect is small.
CITATION LIST
Patent Literature
[0005] PTL 1: Japanese Patent No. 3718964
[0006] PTL 2: Japanese Patent No. 4719432
SUMMARY OF THE INVENTION
[0007] The present invention is to solve the above problems, and
provides a refrigeration cycle device that switches to injection
operation of a two-stage compression system during high load
operation, for example, during low outdoor air temperature while
employing a single-stage compression system that exerts high
efficiency capability during normal operation. This provides a
refrigeration cycle device that exerts a high capability.
[0008] That is, a refrigeration cycle device according to the
present invention includes a compressor including a first
compression chamber and a second compression chamber that are
independent, a condenser, a decompressor, an evaporator, an
injection path configured to introduce intermediate pressure
refrigerant decompressed by the decompressor, a first suction path
configured to introduce low pressure refrigerant from the
evaporator to the first compression chamber, and a second suction
path configured to introduce low pressure refrigerant from the
evaporator to the second compression chamber. The refrigeration
cycle device further includes a communication passage configured to
introduce intermediate pressure refrigerant compressed in the first
compression chamber to the second compression chamber, and a switch
element configured to selectively make the second compression
chamber communicate with the evaporator or make the second
compression chamber communicate with the communication passage. The
injection path introduces the intermediate pressure refrigerant to
the second compression chamber. The refrigerant is compressed in
the first compression chamber and the second compression chamber
independently when the second compression chamber is communicated
with the evaporator, and refrigerant compressed in the first
compression chamber is further compressed in the second compression
chamber when the second compression chamber is communicated with
the communication passage.
[0009] This makes it possible to exert high heating capability
utilizing injection effect by two-stage injection operation that
does not cause pulsation of the injection pipe under the operating
conditions in which pressure difference is large such as operation
at a low outdoor air temperature as a refrigeration cycle device
that injects intermediate pressure gas refrigerant. This also
enables power consumption suppressed high efficient operation by
making each of the two compression chambers perform single-stage
compression from a low pressure to a high pressure during low load
and low differential pressure operation.
BRIEF DESCRIPTION OF DRAWINGS
[0010] FIG. 1 is a diagram illustrating a compressor and a
refrigeration cycle during single-stage compressing operation in a
refrigeration cycle according to the present invention.
[0011] FIG. 2 is a diagram illustrating the compressor and the
refrigeration cycle during two-stage compressing operation in the
refrigeration cycle according to the present invention.
[0012] FIG. 3 is an enlarged view of a compression mechanism
portion structuring the refrigeration cycle according to the
present invention.
[0013] FIG. 4 is a plan view of a compression chamber of a rotary
compressor structuring the refrigeration cycle according to the
present invention.
[0014] FIG. 5 is a diagram illustrating a relation between a
compression chamber volume ratio and an injection ratio in the
refrigeration cycle according to the present invention.
[0015] FIG. 6 is a diagram illustrating a conventional injection
refrigeration cycle using a gas-liquid separator.
DESCRIPTION OF EMBODIMENT
[0016] A first aspect of the present disclosure includes a
compressor including a first compression chamber and a second
compression chamber that are independent, a condenser, a
decompressor, an evaporator, an injection path configured to
introduce intermediate pressure refrigerant decompressed by the
decompressor, a first suction path configured to introduce low
pressure refrigerant from the evaporator to the first compression
chamber, and a second suction path configured to introduce low
pressure refrigerant from the evaporator to the second compression
chamber. The refrigeration cycle device further includes a
communication passage configured to introduce intermediate pressure
refrigerant compressed in the first compression chamber to the
second compression chamber, and a switch element configured to
selectively make the second compression chamber communicate with
the evaporator or make the second compression chamber communicate
with the communication passage. The injection path introduces the
intermediate pressure refrigerant to the second compression
chamber. The refrigerant is compressed in the first compression
chamber and the second compression chamber independently when the
second compression chamber is communicated with the evaporator, and
refrigerant compressed in the first compression chamber is further
compressed in the second compression chamber when the second
compression chamber is communicated with the communication
passage.
[0017] This makes it possible to exert high heating capability
utilizing injection effect by two-stage injection operation that
does not cause pulsation of the injection pipe under the operating
conditions in which pressure difference is large such as operation
at a low outdoor air temperature. This also enables power
consumption suppressed high efficient operation by making each of
the two compression chambers perform single-stage compression from
a low pressure to a high pressure during low load and low
differential pressure operation.
[0018] In a second aspect, in the refrigeration cycle device
according to the first aspect, the second suction path has a
connection part connecting with the injection path on a downstream
side of the switch element.
[0019] This makes overheated refrigerant compressed in the first
compression chamber be mixed with intermediate pressure
refrigerant, which is small in degree of superheat, transmitted
from injection pipe till the overheated refrigerant is introduced
in the second compression chamber, when two-stage compressing
operation is performed. This makes it possible to reduce degree of
superheat of the refrigerant introduced in the second compression
chamber, making it possible to improve compression efficiency in
the second compression chamber. Furthermore, when single-stage
compressing operation is performed, making the pressure of the
refrigerant flowing in the injection pipe be a substantively low
pressure state and using the injection pipe as a bypass circuit of
the refrigerant passing through the evaporator become possible,
making it possible to reduce the gas refrigerant flowing in the
evaporator. This makes it possible to yield efficiency improvement
effect of the evaporator, making it possible to improve
refrigeration cycle efficiency and capability.
[0020] In a third aspect, in the refrigeration cycle device
according to the first aspect, a volume of the first compression
chamber and a volume of the second compression chamber are equal.
Note that a volume ratio only needs to be substantially equal and
may have a difference of about .+-.10%.
[0021] This makes it possible to make the sizes and weights of
eccentric rotation series members such as a shaft eccentric shaft
and a piston equal, making it possible to manufacture the
compressor with a low price.
[0022] In a fourth aspect, in the refrigeration cycle device
according to the first aspect, the compressor is provided around a
shaft and has two eccentric shafts each performing eccentric
rotation, and phases of the two eccentric shafts are deviated by
180 degrees.
[0023] This makes it possible to structure two compression
mechanisms without deviating the gravity center of the rotation
member with respect to a shaft axis direction, making it possible
to suppress vibration of the compressor. Furthermore, allocation
ratios of compression power become equal, making it possible to
perform efficient compressing operation. Note that "deviation by
180 degrees" includes the case of "deviation by substantially 180
degrees".
[0024] In a fifth aspect, in the refrigeration cycle device
according to the second aspect, the second suction path has an
upward gradient part between the connection part and the second
compression chamber.
[0025] This makes the intermediate pressure overheated gas
refrigerant introduced from the first compression chamber be
preferentially introduced to the second compression chamber even
when liquid refrigerant is flown from the injection pipe when the
two-stage injection operation is performed. Liquid component
refrigerant that is large in its specific gravity is evaporated by
heat exchange with overheated gas refrigerant without being
introduced in the second compression chamber. This makes it
possible to keep lubrication of the compressor good and efficiently
perform the two-stage compressing operation.
[0026] In a sixth aspect, in the refrigeration cycle device
according to the first aspect, inverter operation to arbitrarily
change a rotation number of the compressor is performed.
[0027] This makes it possible to perform continuous high efficiency
operation with respect to a wide range capability zone from small
capability to large capability, and to provide a large capability
operation in which the injection effect and high speed operation
are combined during a low outside air temperature.
[0028] A seventh aspect provides the compressor used in the
refrigeration cycle device according to any one of the first aspect
to the sixth aspect.
[0029] Hereinafter, an exemplary embodiment of the present
invention will be described in detail with reference to the
drawings. Note that the present invention is not limited by the
following exemplary embodiment.
First Exemplary Embodiment
[0030] FIG. 1 is a refrigeration cycle diagram during single-stage
compressing operation according to an exemplary embodiment of the
present invention. FIG. 2 is a refrigeration cycle diagram during
two-stage compressing operation according to the exemplary
embodiment. FIG. 3 is an enlarged view of a compression mechanism
portion according to the exemplary embodiment. FIG. 4 is a plan
view of a compression chamber of a rotary compression mechanism
according to the exemplary embodiment.
[0031] As illustrated in FIGS. 1 and 2, a refrigeration cycle
device of the exemplary embodiment includes compressor 1, condenser
2, evaporator 3, decompressors 4, injection pipe 5, and gas-liquid
separator 6.
[0032] A main body of compressor 1 includes, in sealed vessel 11,
motor 12, first compression mechanism 20 structuring first
compression chamber 21, second compression mechanism 30 structuring
second compression chamber 31, and shaft 13. Motor 12 is disposed
above first compression mechanism 20 and second compression
mechanism 30. First compression mechanism 20, second compression
mechanism 30, and motor 12 are coupled with shaft 13. Terminal 14
for supplying electric power to motor 12 is provided at an upper
portion of sealed vessel 11. Oil storage part 15 for retaining
lubricant is formed at the bottom of sealed vessel 11. The main
body of the compressor has a structure of a so-called hermetic
compressor.
[0033] Each of first compression mechanism 20 and second
compression mechanism 30 is a positive displacement fluid
mechanism.
[0034] First compression mechanism 20 includes first cylinder 25,
first piston 26, first vane 27, first spring 29, first frame 60,
and partition plate 40. First piston 26 is disposed inside first
cylinder 25. First piston 26 is fitted with first eccentric shaft
13a of shaft 13. First compression chamber 21 is formed between the
outer periphery of first piston 26 and the inner periphery of first
cylinder 25. First vane groove 28 is formed in first cylinder 25.
First vane 27 and first spring 29 are housed in first vane groove
28. The tip of first vane 27 is in contact with the outer periphery
of the first piston. First vane 27 is pushed toward first piston 26
by first spring 29.
[0035] First frame 60 is disposed at the lower face of first
cylinder 25, and partition plate 40 is disposed at the upper face
of first cylinder 25. First cylinder 25 is sandwiched between first
frame 60 and partition plate 40. In first compression chamber 21, a
first suction chamber and a first compression-discharge chamber are
formed by being partitioned by first vane 27.
[0036] Second compression mechanism 30 includes second cylinder 35,
second piston 36, a second vane (not shown), a second spring (not
shown), second frame 70, and partition plate 40. Second cylinder 35
is concentrically arranged with respect to first cylinder 25.
Second piston 36 is disposed inside second cylinder 35. Second
piston 36 is fitted with a second eccentric shaft (not shown) of
shaft 13. Second compression chamber 31 is formed between the outer
periphery of second piston 36 and the inner periphery of second
cylinder 35. A second vane groove is formed in second cylinder 35.
A second vane and a second spring are housed in the second vane
groove. The tip of the second vane is in contact with the outer
periphery of the second piston. The second vane is pushed toward
second piston 36 by the second spring. Second frame 70 is disposed
at the upper face of second cylinder 35, and partition plate 40 is
disposed at the lower face of the second cylinder 35. Second
cylinder 35 is sandwiched between second frame 70 and partition
plate 40. In second compression chamber 31, a second suction
chamber and a second compression-discharge chamber are formed by
being partitioned by the second vane.
[0037] Furthermore, the eccentricity direction of first eccentric
shaft 13a is deviated from the eccentricity direction of second
eccentric shaft 13b by 180 degrees. That is, the phase of first
piston 26 is deviated from the phase of second piston 36 by 180
degrees in a rotation angle of shaft 13.
[0038] Furthermore, first discharge space 24 in which the
refrigerant compressed by first compression chamber 21 is
discharged is provided in first frame 60. The refrigerant (working
fluid) compressed by first compression chamber 21 is introduced
into first suction chamber 21a of first compression chamber 21
through first suction path 96. The refrigerant discharged from
first compression-discharge chamber 21b of first compression
chamber 21 is flown into first discharge space 24 from first
discharge hole 22 formed in first frame 60.
[0039] Furthermore, first check valve 23 is provided at first
discharge hole 22. First check valve 23 prevents refrigerant from
being flown from first discharge space 24 to first compression
chamber 21. Furthermore, single-stage compression communication
passage 91 and single-stage compression discharge hole 92 are
formed between first discharge space 24 and sealed vessel 11.
Single-stage compression discharge hole 92 is formed at second
frame 70. Single-stage compression communication passage 91 and
single-stage compression discharge hole 92 make first discharge
space 24 communicate with an inside of sealed vessel 11.
Furthermore, third check valve 93 is provided at single-stage
compression discharge hole 92. Third check valve 93 prevents
refrigerant from being flown from the inside of sealed vessel 11 to
first ejection space 24.
[0040] The refrigerant compressed in second compression chamber 31
is introduced into a second suction chamber (not shown) of second
compression chamber 31 through second suction path 97. The
refrigerant discharged from the second compression-discharge
chamber (not shown) of a second compression chamber 31 is
introduced inside sealed vessel 11 from second discharge hole 32.
Second discharge hole 32 is formed at second frame 70.
[0041] Second check valve 33 is provided at second discharge hole
32. Second check valve 33 prevents refrigerant from being flown
from the inside of sealed vessel 11 to second compression chamber
31.
[0042] Two-stage compression communication passage 94 makes first
discharge space 24 connect with switch valve 95 (control element),
and makes first discharge space 24 communicate with second suction
path 97 (FIG. 2) or blocks the communication (FIG. 1) depending on
the state of switch valve 95.
[0043] Discharge path 90 penetrates an upper portion of sealed
vessel 11. Discharge path 90 introduces compressed refrigerant
outside sealed vessel 11. Discharge path 90 is connected to
condenser 2 to supply high-pressure refrigerant to condenser 2.
[0044] First suction path 96 (first connection pipe 53) connects
first compression mechanism 20 and accumulator 50 and introduces
refrigerant to be compressed from accumulator 50 to first
compression chamber 21 of first compression mechanism 20.
[0045] Second suction path 97 connects second compression mechanism
30 and switch valve 95 serving as a control element. To switch
valve 95, an end of second suction path 97, an end of second
connection pipe 54 connected with accumulator 50, and an end of
two-stage compression communication passage 94 are connected.
Switch valve 95 selectively makes one of second connection pipe 54
and two-stage compression communication passage 94 communicate with
second suction path 97 and blocks the path between the other one
and second suction path 97. In other words, switch valve 95
selectively makes second compression chamber 31 communicate with
evaporator 3 or makes second compression chamber 31 communicate
with two-stage compression communication passage 94.
[0046] Injection pipe 5 is connected at an upper portion of second
suction path 97 connecting second compression mechanism 30 and
switch valve 95. Second suction path 97 is equipped with connection
part 80 with injection pipe 5 on the downstream side of switch
valve 95. Second suction path 97 joins the gas refrigerant
introduced from gas-liquid separator 6 through injection pipe 5 and
the refrigerant introduced from switch valve 95 and introduces the
gas refrigerant and the refrigerant to second compression mechanism
30. Second suction path 97 has upward gradient part 97a between
connection part 80 of injection pipe 5 and second compression
mechanism 30. This preferentially introduces gas refrigerant
relatively light in specific gravity to second compression
mechanism 30 when the joined refrigerant is watery refrigerant
including liquid component. Moreover, liquid storage part 97b may
be provided so that liquid refrigerant exchanges heat with
overheated gas refrigerant to be evaporated.
[0047] The refrigerant condensed in condenser 2 is decompressed in
decompressor 4. Gas-liquid separator 6 separates some evaporated
gas refrigerant and liquid refrigerant. The separated liquid
refrigerant further passes through decompressor 4 and is introduced
to evaporator 3 as low-pressure refrigerant. In contrast, gas
refrigerant separated by gas-liquid separator 6 passes through
injection pipe 5 and is joined with the refrigerant introduced from
any one of second connection pipe 54 and two-stage compression
communication passage 94 at second suction path 97, and is
introduced to second compression mechanism 30. In the present
invention, since injection gas is introduced to a stable pressure
region, back flow does not occur in injection pipe 5. However,
means for adjusting or stopping injection pressure may be provided
by providing a close valve or a metering valve at injection pipe
5.
[0048] To evaporator 3, the refrigerant decompressed to a low
pressure by decompressor 4 is introduced, and liquid refrigerant is
evaporated by thermal exchange to be discharged as gas refrigerant.
The discharged refrigerant is introduced to accumulator 50 with
liquid refrigerant that has failed to be evaporated in evaporator
3.
[0049] Accumulator 50 includes accumulation vessel 51, introduction
pipe 52, first connection pipe 53, and second connection pipe 54.
Accumulation vessel 51 has an internal space capable of retaining
liquid refrigerant and gas refrigerant. Introduction pipe 52 is
provided at an upper portion of accumulation vessel 51.
Introduction pipe 52 is connected with evaporator 3 to supply low
pressure refrigerant. First connection pipe 53 and second
connection pipe 54 penetrate bottom portions of accumulation vessel
51 and are opened to the inner space of accumulation vessel 51.
Note that another member such as a baffle may be provided inside
accumulation vessel 51 to prevent liquid refrigerant from being
flown into first connection pipe 53 and second connection pipe 54
from introduction pipe 52. Alternatively, first connection pipe 53
and the second connection pipe may be directly connected with
introduction pipe 52 depending on the type of compressor 1.
[0050] The exemplary embodiment makes it possible to switch between
the refrigeration cycle operation in which the single-stage
compressing operation is simultaneously performed by the two
compression mechanisms and the refrigeration cycle operation in
which the two-stage compressing operation is performed by the two
compression mechanisms with the injection of an intermediate
pressure, by using switch valve 95. Hereinafter, the description
will be specifically described.
[0051] First, the case of performing the single-stage compressing
operation during low differential pressure in which pressure
difference between high pressure and low pressure is small will be
described.
[0052] As illustrated in FIG. 1, second suction path 97 and second
connection pipe 54 are connected by switch valve 95. In contrast,
second suction path 97 and two-stage compression communication
passage 94 are blocked. In this case, first compression mechanism
20 and second compression mechanism 30 are connected to accumulator
50, so that first compression mechanism 20 and second compression
mechanism 30 are connected in parallel.
[0053] The flow of refrigerant in this case will be specifically
described.
[0054] The refrigerant suctioned from first suction path 96 is
compressed by first compression mechanism 20, and discharged in
first discharge space 24 through first discharge hole 22. On the
other hand, two-stage compression communication passage 94
communicating with first discharge space 24 is blocked by switch
valve 95. Consequently, the pressure in first discharge space 24
increases to the level equal to the pressure inside sealed vessel
11. As a result, the refrigerant discharged in first discharge
space 24 passes through single-stage compression communication
passage 91 and single-stage compression discharge hole 92, opens
third check valve 93, and is discharged inside sealed vessel 11.
Furthermore, since second suction path 97 is connected with
accumulator 50 via switch valve 95, the refrigerant suctioned from
second suction path 97 is compressed by second compression
mechanism 30, and is discharged inside sealed vessel 11 through
second discharge hole 32. In this context, the refrigerants
compressed by respective first compression mechanism 20 and second
compression mechanism 30 join inside sealed vessel 11 to be
introduced outside sealed vessel 11 through discharge path 90.
[0055] Herein, given that the suction volume of first compression
mechanism 20 is V1 and the suction volume of second compression
mechanism 30 is V2, the suction volume during single-stage
compressing operation becomes V1+V2. In the exemplary embodiment,
by making V1 and V2 substantially same, workloads of the respective
two compression mechanisms are equalized, enabling high efficiency
compression behaviors. Furthermore, injection pipe 5 is connected
to second suction path 97, making it possible to use injection pipe
5 as a bypass of evaporator 3. That is, by adjusting decompressor
4, the pressure of gas-liquid separator 6 is lowered to be a low
pressure to make only gas refrigerant having no latent heat be
bypassed from injection pipe 5 to second compression mechanism 30.
This makes it possible to preferentially transmit the liquid
refrigerant that essentially needs to be introduced to evaporator
3, also making it possible to perform higher efficient operation by
pressure loss reduction effect in evaporator 3.
[0056] Next, the case of performing two-stage injection compressing
operation during high differential pressure in which pressure
difference between high pressure and low pressure is large will be
described.
[0057] As illustrated in FIG. 2, second suction path 97 and
two-stage compression communication passage 94 are connected by
switch valve 95, and connection between second suction path 97 and
second connection pipe 54 is blocked. In this case, only the first
suction path is connected to accumulator 50, so that first
compression mechanism 20 and second compression mechanism 30 are
connected in series.
[0058] The flow of refrigerant in this case will be specifically
described.
[0059] The refrigerant suctioned from first suction path 96 is
compressed by first compression mechanism 20, and discharged in
first discharge space 24 through first discharge hole 22. Herein,
two-stage compression communication passage 94 communicating with
first discharge space 24 is connected to second suction path 97 via
switch valve 95. Consequently, the refrigerant discharged in first
discharge space 24 joins the refrigerant introduced from injection
pipe 5 in second suction path 97, and compressed by second
compression mechanism 30. The refrigerant compressed by second
compression mechanism 30 is discharged inside sealed vessel 11
through second discharge hole 32. Herein, first compression
mechanism 20 and second compression mechanism 30 are connected in
series, so that the pressure in first discharge space 24 becomes an
intermediate pressure lower than the discharge pressure of second
compression mechanism 30. Consequently, third check valve 93 is
closed by the pressure difference between first discharge space 24
and the inside of sealed vessel 11. As a result, all of the
refrigerant compressed by first compression mechanism 20 is flown
into second compression mechanism 30. Furthermore, the refrigerant
compressed by second compression mechanism 30 is discharged inside
sealed vessel 11, and introduced outside the sealed vessel through
discharge path 90.
[0060] In the ratio between gas refrigerant and liquid refrigerant
among the refrigerant separated by the gas-liquid separator, gas
component increases as the pressure difference between high
pressure and low pressure of the refrigeration cycle becomes
larger. In the case of the conventionally proposed two-stage
dedicated compressor, securing sufficient gas injection refrigerant
is impossible under low load conditions where pressure difference
is small, so that it is preferable to preliminarily design the
heights of first cylinder 25 and second cylinder 35 to be different
in order to perform the two-stage compressing operation. As a
result, suction volume V1 of first compression mechanism 20 becomes
larger than suction volume V2 of second compression mechanism 30.
However, in the exemplary embodiment, the two-stage compressing
operation is limited only to a high differential pressure condition
that allows injection gas to be sufficiently secured, enabling
suction volume V1 of first compression mechanism 20 to be
substantially equal to suction volume V2 of second compression
mechanism 30.
[0061] This enables the heights of first cylinder 25 and second
cylinder 35 to be equal to thereby make the shapes and heights of
first piston 26 and second piston 36 equal. Likewise, this enables
the shapes and heights of first eccentric shaft 13a and the second
eccentric shaft to be equal. As a result, deviating the phases of
first eccentric shaft 13a and the second eccentric shaft by 180
degrees makes it possible to structure two compression mechanisms
without deviating the gravity center of a rotation member from the
shaft center, making it possible to provide low vibration from a
low speed to a high speed.
[0062] Furthermore, the volume ratio of second compression
mechanism 30 can be made larger than that of the conventional
two-stage dedicated compressor, making it possible to cope with
refrigeration recycle operation with a higher injection rate during
high differential pressure operation. This makes it possible to
sufficiently exert ability improvement effects during low outside
air temperature operation. This point will be described below in
detail.
[0063] In the case of the conventional two-stage dedicated
compressor, the volume of the second compression chamber needs to
be made smaller than the volume of the first compression chamber to
keep the two-stage compressing operation in consideration of the
need to perform operation with no injection during low load
operation. The graph illustrated in FIG. 5 illustrates the volume
ratio of the second compression chamber with respect to the first
compression chamber and the maximum ratio of gas injection
refrigerant capable of being passed through the injection pipe
among the refrigerant in the refrigeration cycle (called injection
ratio) when outside air temperature is assumed to be -30.degree. C.
The configuration of the present invention makes it possible to
increase the volume ratio of second compression mechanism 30 as
compared with the configuration of the conventional two-stage
dedicated compressor in which the volume ratio of the second
compression chamber is small, making it possible to increase the
injection ratio. This makes it possible to exert greater injection
effect during low outside air temperature to provide high
capability.
[0064] Next, separation of oil from refrigerant will be
described.
[0065] The compressor of a high pressure type in which refrigerant
is once discharged inside sealed vessel 11, passed through
discharge path 90, and thereafter introduced outside sealed vessel
11 typically has oil storage part 15 in the sealed vessel. This is
to prevent leakage of lubricant of each slide portion of the
compression mechanism and refrigerant being compressed. Compressor
1 used in the refrigeration cycle device according to the exemplary
embodiment also has oil storage part 15 to prevent leakage of the
lubricant of each slide portion of the compression mechanism and
the refrigerant being compressed.
[0066] Some of the oil introduced in the compression mechanism
portion is mixed with refrigerant during compression and the
refrigerant and the oil are discharged together inside sealed
vessel 11. Oil, which is larger in specific gravity than that of
refrigerant, of the fluid that is mixture of the refrigerant and
the oil discharged inside sealed vessel 11 is separated from the
refrigerant by centrifugal force and gravitational force while
being moved upward at the vicinity of motor 12 or inside the sealed
vessel 11. The separated oil returns to oil storage part 15 inside
sealed vessel 11. The above behavior enables the high-pressure type
compressor according to the exemplary embodiment capable of
separating the oil from the refrigerant in sealed vessel 11 to
reduce the amount of oil introduced outside sealed vessel 11
through discharge path 90, preventing condenser 2 and evaporator 3
from being lowered in their efficiency. This makes it possible to
provide a refrigeration cycle device operable with high
efficiency.
[0067] According to the present exemplary embodiment, in both of
the single-stage compressing operation and the two-stage injection
compressing operation, all refrigerant is introduced outside sealed
vessel 11 through discharge path 90 after discharged inside sealed
vessel 11. This enables the refrigerant to be discharged outside
sealed vessel 11 after refrigerant and oil are fully separated
inside sealed vessel 11, preventing condenser 2 and evaporator 3
from being lowered in their efficiency. This also makes it possible
to reduce oil to be taken out from sealed vessel 11, making it
possible to stably secure oil in oil storage part 15 to prevent
seizure and abnormal wear of the components of the compression
mechanism portion.
[0068] Note that in the exemplary embodiment, first compression
mechanism 20 is disposed on the far side of motor 12 and second
compression mechanism 30 is disposed on the near side of the motor
12. That is, motor 12, second compression mechanism 30, and first
compression mechanism 20 are aligned in this order along the axis
direction of shaft 13. This order makes it possible to make first
discharge space 24 wide without being interfered by motor 12 and
the like as illustrated in FIGS. 1 and 2, making it possible to
sufficiently yield refrigerant pulsation lowering effect in first
discharge space 24. This makes it possible to further reduce
pressure pulsation in second suction path 97 connected with
injection pipe 5, making it possible to reduce vibration and noise
of refrigerant pipe.
[0069] Note that first vane 27 and the second vane may be unified
with first piston 26 and second piston 36, respectively. That is,
the vane and the piston may be a so-called swing piston.
Furthermore, first piston 26 and first vane 27 may be jointed with
second piston 36 and the second vane.
[0070] Furthermore, the effects of the present invention can be
also obtained by other positive-displacement compression mechanism
such as a scroll compression system, a screw compression system,
and the like, non positive-displacement compression mechanism such
as a turbo type, and a combination (not shown) of the different
compression systems without using the rotary compression system for
first compression mechanism 20 and second compression mechanism
30.
[0071] Motor 12 is structured by stator 12a and rotor 12b. Stator
12a is fixed to the inner periphery of sealed vessel 11. Rotor 12b
is fixed to shaft 13 and rotates with shaft 13. By the motor 12,
first piston 26 and second piston 36 are moved inside first
cylinder 25 and second cylinder 35, respectively. As motor 12,
motors that can change rotation numbers thereof such as an interior
permanent magnet synchronous motor (IPMSM) and a surface permanent
magnet synchronous motor (SPMSM) can be used.
[0072] Controller 8 adjusts the rotation number of motor 12, that
is, a rotation number of compressor 1 by controlling inverter 7. As
controller 8, a digital signal processor (DSP) can be used
including an A/D conversion circuit, an input-output circuit, an
arithmetic circuit, a storage device, and the like.
INDUSTRIAL APPLICABILITY
[0073] The present invention is useful for a refrigeration cycle
device that can be used in an electrical product such as a hydronic
heater, an air conditioner, and a hot water dispenser in which
their evaporator is used under a low temperature environment.
REFERENCE MARKS IN THE DRAWINGS
[0074] 1 compressor [0075] 2 condenser [0076] 3 evaporator [0077] 4
decompressor [0078] 5 injection pipe [0079] 6 gas-liquid separator
[0080] 7 inverter [0081] 7 controller [0082] 8 sealed vessel [0083]
11 motor [0084] 12a stator [0085] 12b rotor [0086] 13 shaft [0087]
13a first eccentric shaft [0088] 13b second eccentric shaft [0089]
14 terminal [0090] 15 oil storage part [0091] 20 first compression
mechanism [0092] 21 first compression chamber [0093] 21a first
suction chamber [0094] 21b first compression-discharge chamber
[0095] 22 first discharge hole [0096] 23 first check valve [0097]
24 first discharge space [0098] 25 first cylinder [0099] 26 first
piston [0100] 27 first vane [0101] 28 first vane groove [0102] 29
first spring [0103] 30 second compression mechanism [0104] 31
second compression chamber [0105] 32 second discharge hole [0106]
33 second check valve [0107] 35 second cylinder [0108] 35 second
piston [0109] 36 second vane groove [0110] 38 partition plate
[0111] 40 accumulator [0112] 51 accumulation vessel [0113] 52
introduction pipe [0114] 53 first connection pipe [0115] 54 second
connection pipe [0116] 60 first frame [0117] 70 second frame [0118]
80 connection part [0119] 90 discharge path [0120] 91 single-stage
compression communication passage [0121] 92 single-stage
compression discharge hole [0122] 93 third check valve [0123] 94
two-stage compression communication passage [0124] 95 switch valve
(control element) [0125] 96 first suction path [0126] 97 second
suction path [0127] 97a upward gradient part [0128] 97b liquid
storage part
* * * * *