U.S. patent application number 13/254192 was filed with the patent office on 2011-12-29 for refrigerator.
This patent application is currently assigned to MITSUBISHI ELECTRIC CORPORATION. Invention is credited to Takashi Ikeda, Tomotaka Ishikawa, Yasutaka Ochiai, Hiroshi Sata, Kousuke Tanaka.
Application Number | 20110314854 13/254192 |
Document ID | / |
Family ID | 42780531 |
Filed Date | 2011-12-29 |
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United States Patent
Application |
20110314854 |
Kind Code |
A1 |
Sata; Hiroshi ; et
al. |
December 29, 2011 |
REFRIGERATOR
Abstract
A refrigerator provided with a refrigerant circuit in which a
compressor, a condenser, a liquid container, a supercooling heat
exchange portion, a throttle valve, and an evaporator connected in
this order by piping, a return circuit that branches from a
downstream position in a refrigerant flowing direction of the
supercooling heat exchange portion in the refrigerant circuit and
leads to an intermediate-pressure chamber of the compressor via the
supercooling heat exchange portion, a supercooling throttle valve
with a variable valve opening-degree that is disposed on a
refrigerant inlet side of the supercooling heat exchange portion in
the return circuit, and operation state detecting means that
detects operation state data in the refrigerant circuit, in which
dryness-degree calculating means that calculates a dryness-degree
of the refrigerant on the outlet side of the supercooling heat
exchange portion in the return circuit on the basis of the detected
operation state data and supercooling throttle valve control means
that controls the valve opening-degree of the supercooling throttle
valve so that the calculated dryness-degree gets close to the value
of 1.
Inventors: |
Sata; Hiroshi; (Tokyo,
JP) ; Ishikawa; Tomotaka; (Tokyo, JP) ;
Ochiai; Yasutaka; (Tokyo, JP) ; Tanaka; Kousuke;
(Tokyo, JP) ; Ikeda; Takashi; (Tokyo, JP) |
Assignee: |
MITSUBISHI ELECTRIC
CORPORATION
TOKYO
JP
|
Family ID: |
42780531 |
Appl. No.: |
13/254192 |
Filed: |
March 19, 2010 |
PCT Filed: |
March 19, 2010 |
PCT NO: |
PCT/JP2010/001974 |
371 Date: |
September 1, 2011 |
Current U.S.
Class: |
62/190 |
Current CPC
Class: |
F25B 2700/21152
20130101; F25B 2600/0253 20130101; Y02B 30/70 20130101; F25B
2600/2513 20130101; F25B 41/40 20210101; F25B 2600/21 20130101;
F25B 2400/13 20130101; F25B 2600/2509 20130101; F25B 49/02
20130101 |
Class at
Publication: |
62/190 |
International
Class: |
F25B 41/04 20060101
F25B041/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 6, 2009 |
JP |
2009-076781 |
Claims
1. A refrigerator that has a refrigerant circuit in which a
compressor, a condenser, a liquid container, a supercooling heat
exchange portion, a throttle valve, and an evaporator are connected
in this order by piping, a return circuit that branches from a
downstream position in a refrigerant flowing direction of the
supercooling heat exchange portion in said refrigerant circuit and
leads to an intermediate-pressure chamber of the compressor via
said supercooling heat exchange portion, a supercooling throttle
valve with a variable valve opening-degree that is disposed on a
refrigerant inlet side of the supercooling heat exchange portion in
said return circuit, and operation state detecting means that
detects operation state data in said refrigerant circuit,
comprising: dryness-degree calculating means that calculates a
dryness-degree of the refrigerant on the outlet side of the
supercooling heat exchange portion in said return circuit on the
basis of the operation state data detected by said operation state
detecting means; and supercooling throttle valve control means that
controls the valve opening-degree of said supercooling throttle
valve so that the dryness-degree calculated by said dryness-degree
calculating means gets close to the value of 1 (a predetermined
value).
2. The refrigerator of claim 1, wherein the operation state
detecting means includes: operation capacity detecting means that
detects an operation capacity of the compressor with variable
capacity; condensation temperature detecting means that detects a
refrigerant condensation temperature in the condenser; evaporation
temperature detecting means that detects a refrigerant evaporation
temperature in the evaporator; and liquid-refrigerant temperature
detecting means that detects a refrigerant temperature on the
refrigerant outlet side of the supercooling heat exchange portion
in said refrigerant circuit.
3. The refrigerator of claim 1, wherein the operation state
detecting means includes: supercooling-inlet-side refrigerant
temperature detecting means that detects a refrigerant temperature
on the refrigerant inlet side of the supercooling heat exchange
portion in said return circuit; and supercooling-outlet-side
refrigerant temperature detecting means that detects a refrigerant
temperature on the refrigerant outlet side of the supercooling heat
exchange portion in said return circuit.
4. The refrigerator of claim 1, comprising: a plurality of common
compressor-side modules in which the compressor and the condenser
are disposed; a liquid-collection-side module in which a liquid
container to which each of said plurality of compressor-side
modules is connected and which contains a liquid refrigerant from
the condenser of said plurality of compressor-side modules is
disposed; a plurality of parallel pipelines in which the liquid
refrigerant from said liquid container is distributed in parallel
into the number corresponding to said compressor-side modules; a
common set composed of a return circuit, a supercooling heat
exchange portion, and a supercooling throttle valve disposed in
each of said parallel pipelines; a throttle valve that throttles
the refrigerant merged from said plurality of parallel pipelines;
and an evaporator that evaporates the refrigerant from said
throttle valve, connected in this order by piping so as to
constitute a refrigerant circuit.
Description
TECHNICAL FIELD
[0001] The present invention relates to a refrigerator provided
with a refrigerant circuit that connects a compressor, a condenser,
a supercooling heat exchange portion, a throttle valve, and an
evaporator connected by piping.
BACKGROUND ART
[0002] Hitherto, as for this type of a refrigerator, a refrigerator
described in the following Patent Literature 1, for example, has
been known. The refrigerator described in this document is provided
with a refrigerant circuit in which a compressor, a condenser, a
supercooling heat exchanger portion, a throttle valve, and an
evaporator connected in this order by piping, an
intermediate-pressure injection circuit branching at a downstream
position in a refrigerant flowing direction of the supercooling
heat exchanger portion in the refrigerant circuit and leading to an
intermediate pressure chamber of the compressor, a throttle valve
for an intermediate pressure having a variable valve opening-degree
disposed in the intermediate-pressure injection circuit, a suction
injection circuit branching from a downstream position in the
refrigerant flowing direction of the supercooling heat exchanger
portion in the refrigerant circuit and leading to a refrigerant
suction side of the compressor via the supercooling heat exchanger
portion, a supercooling throttle valve having a variable valve
opening-degree disposed on the refrigerant inlet side of the
supercooling heat exchanger portion in the suction injection
circuit, and operation state detecting means that detects operation
state data in the refrigerant circuit such as a discharge
temperature sensor, a temperature sensor on the outlet side of the
supercooling heat exchanger portion of the refrigerant circuit, a
temperature sensor on the outlet side of the supercooling heat
exchange portion in the suction injection circuit.
[0003] This refrigerator is configured such that by controlling an
opening-degree of the throttle valve for an intermediate pressure
in the intermediate-pressure injection circuit, a discharge gas
refrigerant temperature of the compressor is controlled. Also, by
controlling the opening-degree of the supercooling throttle valve
in the suction injection circuit, re-evaporation of the refrigerant
is prevented by supercooling the refrigerant on the downstream side
of the condenser and excessive filling of the refrigerant and
deterioration in refrigerating capacity are prevented.
CITATION LIST
Patent Literature
[0004] Patent Literature 1: Japanese Unexamined Patent Application
Publication No. 2005-274085
SUMMARY OF INVENTION
Technical Problem
[0005] The above prior-art refrigerator has two injection circuits
that are an intermediate-pressure injection circuit and a suction
injection circuit and also has a throttle valve for an
intermediate-pressure and a supercooling throttle valve
accordingly, and thus, pipeline configuration and control
configuration become complicated, and manufacturing cost is
high.
[0006] Also, since the refrigerant supercooled in the supercooling
heat exchanger portion is returned to the suction side of the
compressor by a suction injection circuit, operation must be low
efficiency.
[0007] Also, since specifications of the supercooling heat
exchanger portions are different by each model of different
operation capacity, the number of production lot becomes small, and
cost is raised, which is a problem. This problem is particularly
remarkable with the large-capacity model whose number of production
lot is small.
[0008] The present invention was made in view of the above
prior-art problems and an object thereof is to provide a
refrigerator that can be manufactured inexpensively with a simple
configuration and that is capable of highly efficient
operation.
Solution to Problem
[0009] In order to achieve the above object, a refrigerator
according to the present invention is a refrigerator provided with
a refrigerant circuit in which a compressor, a condenser, a liquid
container, a supercooling heat exchange portion, a throttle valve,
and an evaporator connected in this order by piping, a return
circuit that branches from a downstream position in a refrigerant
flowing direction of the supercooling heat exchange portion in the
refrigerant circuit and leads to an intermediate-pressure chamber
of the compressor via the supercooling heat exchange portion, a
supercooling throttle valve with a variable valve opening-degree
that is disposed on a refrigerant inlet side of the supercooling
heat exchange portion in the return circuit, and operation state
detecting means that detects operation state data in the
refrigerant circuit, characterized by having dryness-degree
calculating means that calculates dryness-degree of the refrigerant
on the outlet side of the supercooling heat exchange portion in the
return circuit on the basis of the operation state data detected by
the operation state detecting means and supercooling throttle valve
control means that controls the valve opening-degree of the
supercooling throttle valve so that the dryness-degree calculated
by the dryness-degree calculating means gets close to the value of
1.
Advantageous Effects of Invention
[0010] According to the refrigerator according to the present
invention, the refrigerator is provided with the return circuit
that branches from the downstream position in the refrigerant
flowing direction of the supercooling heat exchange portion in the
refrigerant circuit and leads to the intermediate-pressure chamber
of the compressor via the supercooling heat exchange portion and
the supercooling throttle valve with the variable valve
opening-degree that is disposed on the refrigerant inlet side of
the supercooling heat exchange portion in the return circuit, and
the refrigerant dryness-degree on the outlet side of the
supercooling heat exchange portion of the return circuit is
calculated from the detected operation state data and the valve
opening-degree of the supercooling throttle valve is controlled so
that the calculated dryness-degree gets close to the value of 1,
and thus, by adding supercooling to the intermediate pressure in
the compressor, the coefficient of performance (COP) of the
refrigerant circuit can be improved as compared with the case of
addition of supercooling to the low pressure side (compressor
suction side) as in the prior-art technology. Also, as compared
with the prior-art technology, the type of pipelines and components
of the throttle valves constituting the return circuit (injection
circuit) and their control system can be reduced for one system,
which can simplify the constitution and reduce manufacturing
cost.
BRIEF DESCRIPTION OF DRAWINGS
[0011] [FIG. 1] FIG. 1 is a refrigerant circuit configuration
diagram of a refrigerator according to Embodiment 1 and Embodiment
2 of the present invention.
[0012] [FIG. 2] FIG. 2 is a diagram illustrating a refrigerator
condensation unit of the refrigerator, in which (a) is a front
view, (b) is a left side view, (c) is a right side view, and (d) is
a plan view.
[0013] [FIG. 3] FIG. 3 is a flowchart illustrating a control
procedure of the refrigerator.
[0014] [FIG. 4] FIG. 4 is a diagram illustrating a refrigerating
cycle operation of the refrigerator. (a) is a Mollier diagram
illustrating a state in which dryness of a refrigerant on an outlet
side of the refrigerant of the supercooling heat exchange portion
in a return circuit is 1, (b) is a Mollier diagram illustrating a
state in which dryness of the refrigerant on the outlet side of the
refrigerant of the supercooling heat exchange portion in the return
circuit is larger than 1, and (c) is a Mollier diagram illustrating
a state in which dryness of the refrigerant on the outlet side of
the refrigerant of the supercooling heat exchange portion in the
return circuit is smaller than 1.
[0015] [FIG. 5] (a) is a front view of a refrigerator condensation
unit according to Embodiment 3 of the present invention, and (b) is
a front view of a refrigerator condensation unit according to
Embodiment 4 of the present invention.
DESCRIPTION OF EMBODIMENTS
Embodiment 1
[0016] FIG. 1 is a refrigerant circuit configuration diagram of a
refrigerator according to Embodiment 1 and Embodiment 2 of the
present invention, and FIG. 2 is a diagram illustrating a
refrigerator condensation unit of the refrigerator, in which (a) is
a front view, (b) is a left side view, (c) is a right side view,
and (d) is a plan view.
[0017] In each figure, the refrigerator according to this
embodiment is provided with the refrigerator condensation unit
composed of one liquid-collection-side module 1 and three
compressor-side modules 2, 2, and 2 installed on an upper face 40
of the liquid-collection side module 1 and connected. All of these
three compressor-side modules 2, 2, and 2 have a common structure
compatible with one another.
[0018] Each of the compressor-side modules 2 is provided with a
plate-shaped first base frame 37 at the bottom portion. On the
first base frame 37, a compressor 3, an accumulator 27, an oil
separator 4, an oil regulator 36, and a condenser 6 are disposed.
In the compressor-side module 2, a first opening/closing valve 30
is disposed in the middle of a refrigerant pipeline 26 connected to
the suction side of the accumulator 27. Between the compressor 3
and the first opening/closing valve 30 in the refrigerant pipeline
26, a first connecting member 33 that connects the refrigerant
pipeline 26 is disposed in a separable fashion. The discharge side
of the accumulator 27 is connected to the suction side of the
compressor 3 by the refrigerant pipeline 48. The discharge side of
the compressor 3 and the condenser 6 are connected by a pipeline
via the oil separator 4. The refrigerant in the condenser 6 is
cooled by air blown from an air blower 5. To the middle of a
refrigerant pipeline 7 connected to the outlet side of the
condenser 6, a second opening/closing valve 31 is disposed. On the
upstream side of the second opening/closing valve 31 in the
refrigerant pipeline 7, a second connecting member 34 that connects
the refrigerant pipeline 7 capable of separation is disposed. To
the compressor 3, the oil regulator 36 is connected by a pipeline.
To this oil regulator 36, an oil equalizing pipeline 51 that
connects the oil regulators 36 and 36 to each other of the other
compressor-side modules 2 and 2 is connected.
[0019] In the middle of the oil equalizing pipeline 51, a fourth
opening/closing valve 52 is disposed. Between the fourth
opening/closing valve 52 and the oil regulator 36 in the oil
equalizing pipeline 51, a fourth connecting member 53 that connects
the oil equalizing pipeline 51 capable of separation is disposed.
Also, a return circuit 29 that allows the refrigerant from the heat
exchanger portion 28 for supercooling of the liquid-collection-side
module 1, which will be described later in detail, to flow is
connected to an intermediate-pressure chamber 3A of the compressor
3. In the middle of the return circuit 29, a third connecting
member 35 that connects the return circuit 29 capable of separation
is disposed. The configurations of the above-described first
connecting member 33, the second connecting member 34, the third
connecting member 35, and the fourth connecting member 53 are not
particularly limited and embodied by a flare nut, here, for
example.
[0020] The three compressor-side modules 2, 2, and 2 are arranged
side by side in the horizontal direction, and the first base frame
37 is fixed onto the casing upper face 40 of the
liquid-collection-side module 1 by a set screw or the like. The
side faces of the right and left outer compressor-side modules 2
and 2 are covered by grid plates 50 and 50 with good ventilation.
An opening above the air blower 5 in each compressor-side module 2
is covered by a bell mouse plate 46. On the other hand, on a bottom
plate of the liquid-collection-side module 1, a liquid container 10
that contains liquid refrigerants from the three compressor-side
modules 2, 2, and 2 is disposed.
[0021] Refrigerant pipelines 7, 7, and 7 leading the condensers 6,
6, and 6 of the three compressor-side modules 2, 2, and 2 are
connected to the refrigerant pipeline 9 via two merging pipe
portions 8 and 8, which are three-way pipes. This refrigerant
pipeline 9 is connected to the liquid container 10 of the
liquid-collection-side module 1. The refrigerant pipelines 26, 26,
and 26 connected to the accumulators 27, 27, and 27, respectively,
are connected to the refrigerant pipeline 24 via two distribution
pipe portions 25 and 25, which are three-way pipes. The refrigerant
pipeline 11 from the liquid container 10 is connected to three
parallel pipelines 13, 13, and 13 corresponding to the number of
the compressor-side modules 2 via distribution pipelines 12 and 12
and further connected to a refrigerant pipeline 15 via merging pipe
portions 14 and 14. In the middles of the parallel pipelines 13,
13, and 13, the supercooling heat exchange portions 28, 28, and 28
are provided. Each of the supercooling heat exchange portion 28
exchanges heat between the refrigerant in the return circuit 29 and
the refrigerant in the parallel pipeline 13. On the refrigerant
inlet side of the supercooling heat exchange portion 28 in the
return circuit 29, a supercooling throttle valve 49 (LEV) with a
variable valve opening-degree is disposed.
[0022] In this supercooling heat exchange portion 28, a
supercooling-degree of the refrigerant in the parallel pipeline 13
is increased by the refrigerant throttled by a supercooling
throttle valve 49 of the return circuit 29, and the refrigerant in
the return circuit 29 is returned to the compressor 3. Between a
branch portion from the parallel pipeline 13 in the return circuit
29 and the supercooling heat exchange portion 28, a third
opening/closing valve 32 is provided. Then, the refrigerant
pipeline 15 from the merging pipe portion 14 is connected to a
refrigerant pipeline 17.
[0023] The above refrigerator constitutes a refrigerant circuit by
being connected to the throttle valve 20 and the evaporator 21 by a
pipeline. In this case, the refrigerant pipeline 17 of the
refrigerator is connected by a refrigerant pipeline 19 and a
connecting pipe portion 18 connected to the throttle valve 20. The
refrigerant pipeline 24 of the refrigerator is connected to the
refrigerant pipeline 22 from the evaporator 21 by a connecting pipe
portion 23. In the refrigerant pipeline on the outlet side of the
oil separator 4, a high-pressure sensor (an example of condensation
temperature detecting means) 65 that detects a refrigerant
condensation temperature is disposed. The refrigerant evaporation
temperature is calculated by converting the high-pressure side
refrigerant pressure detected by the high-pressure sensor 65 to a
saturated temperature. In the refrigerant pipeline 48 on the
suction side of the compressor 3, a low-pressure sensor (an example
of evaporation temperature detecting means) 66 that detects a
refrigerant evaporation temperature is disposed. The refrigerant
evaporation temperature is calculated by converting a refrigerant
pressure on the low-pressure side detected by the low-pressure
sensor 66 to a saturated temperature. In the parallel pipeline 13
on the outlet side of the supercooling heat exchange portion 28 in
the refrigerant circuit, a temperature sensor (an example of
liquid-refrigerant temperature detecting means) 67 that detects a
liquid-refrigerant temperature is disposed. On the suction side of
the compressor 3 in the refrigerant circuit, a temperature sensor
70 is disposed.
[0024] FIG. 1 shows only a detailed configuration of one of the
compressor-side modules 2, while the detailed configurations of the
remaining two compressor-side modules 2 are omitted, but the
detailed configurations of these remaining two compressor-side
modules 2 are the same as that of the illustrated compressor-side
module 2.
[0025] Also, the refrigerator of this embodiment is provided with a
controller 60. The controller 60 is embodied by a general-purpose
micro-processing unit MPU, for example, and has a function of
operation state detecting means 61 that detects operation state
data in the refrigerant circuit, a function of dryness-degree
calculating means 62 that calculates dryness-degree Xmo of the
refrigerant on the outlet side of the supercooling heat exchange
portion 28 of the return circuit 29 from the operation state data
detected by the operation state detecting means 61, a function of
operation capacity detecting means 61 that detects a driving
frequency (corresponding to a driving capacity) outputted to an
inverter device (not shown) that drives a motor of the compressor 3
with variable capacity, and a function of supercooling throttle
valve control means 64 that controls a valve opening-degree of the
supercooling throttle valve 49 so that the dryness-degree Xmo
calculated by the dryness-degree calculating means 62 gets close to
the value of 1. That is, the operation state detecting means in the
present invention includes the functions of the operation state
detecting means 61 of the controller 60, the high-pressure sensor
65, the low-pressure sensor 66, and the temperature sensor 67.
[0026] A refrigerant flow operation of the refrigerator constituted
as above will be described. In each compressor-side module 2, a
high-temperature high-pressure gas refrigerant discharged from the
compressor 3 passes through the oil separator 4, is cooled by the
condenser 6, turns into a liquid refrigerant and flows through the
refrigerant pipeline 7. The liquid refrigerants from the respective
refrigerant pipelines 7 merge in the merging pipe portions 8 and 8
and flow through the refrigerant pipeline 9 into the liquid
container 10. The liquid refrigerant from the liquid container 10
passes through the refrigerant pipeline 11, is distributed in the
distribution pipelines 12 and 12 into the parallel pipelines 13,
13, and 13 and flows into the supercooling heat exchange portions
28, 28, and 28, respectively. The liquid refrigerant in the
parallel pipeline 13 in each supercooling heat exchange portion 28
flows into the return circuit 29 on the downstream side, is further
cooled by the refrigerant having been throttled by the supercooling
throttle valve 49 and has its supercooling-degree increased. On the
other hand, the liquid refrigerants of the refrigerant circuit
having passed through the parallel pipelines 13, 13, and 13 merge
in the merging pipe portions 14 and 14, flow through the
refrigerant pipeline 15 and reach the refrigerant pipeline 17. The
liquid refrigerant of the refrigerant pipeline 17 extends from the
refrigerant pipeline 19 to the throttle valve 20. The refrigerant
is throttled in the throttle valve 20, becomes a gas-liquid
two-phase refrigerant and flows into the evaporator 21. The
refrigerant receives heat in the evaporator 21 and becomes a gas
refrigerant and flows through the refrigerant pipeline 22. The gas
refrigerant in the refrigerant pipeline 22 flows into the
refrigerant pipeline 24 of the refrigerator and is distributed by
the distribution pipe portions 25 and 25 into the refrigerant
pipelines 26, 26, and 26 leading to the compressor-side modules 2,
2, and 2. Then, the gas refrigerant flowing through the refrigerant
pipeline 26 of each compressor-side module 2 flows into the
respective accumulators 27 and returns to the suction side of the
compressor 3 via the refrigerant pipeline 48. The above
refrigerating cycle operation is performed repeatedly.
[0027] Here, a control operation by the controller 60 of this
refrigerator will be described by referring to a flowchart in FIG.
3.
[0028] First, at start of the control operation, the controller 60
determines at Step S1 whether or not 10 seconds have elapsed since
the compressor 3 was started. If 10 seconds have not elapsed yet
(NO at the same Step), as an instruction opening-degree to be
outputted to a driver of the supercooling throttle valve (LEV) 49,
a lowest opening-degree of the supercooling throttle valve 49 is
outputted (Step S2), and the routine returns to the start of the
control operation. On the other hand, if exactly 10 seconds have
elapsed since the start (YES at Step S1), it is determined at Step
S3 whether or not 10 seconds have elapsed since the compressor 3
was started. If 10 seconds or more have elapsed since the start
(NO), at Step S4, it is determined whether or not next driving
frequency for an inverter device determined by the calculation is
to be increased by 20% and more over the driving frequency
currently applied. If the next driving frequency is scheduled to be
increased by 20% and more over the current driving frequency (YES),
the processing goes to Step S5. If the driving frequency is to be
largely changed, an initial opening-degree is re-calculated in
order to improve follow-up performances. If it is exactly 10
seconds after the start of the compressor 3 at Step S3 (YES at the
same Step), the processing goes to Step S5.
[0029] At Step S5, the controller 60 determines an LEV
opening-degree A of the supercooling throttle valve 49 on the basis
of the current operation frequency detected by the operation
capacity detecting means 64, the condensation temperature obtained
by the high-pressure sensor 65, the evaporation temperature
obtained by the low-pressure sensor 66, and the sucked gas
temperature detected by the temperature sensor 70. At the
subsequent Step 6, the opening initial value A of the previous
processing flow is compared with the current opening-degree LEV0,
and the larger value is used as the opening-degree value to be
outputted to the supercooling throttle valve 49 next time (Step
S6), and the routine returns to the control operation start.
[0030] On the other hand, at Step S4, if the operation frequency to
be determined next time is not to be increased by 20% or more over
the current operation frequency (NO at Step S4), the controller 60
calculates an opening-degree change margin .DELTA.LEVsc at Step S7
so that the refrigerant dryness Xmo on the outlet side of the
supercooling heat exchanger 28 gets close to 1. The calculation
method at this time is as described in the following calculating
method (1):
[0031] Calculation method (1): "Method of determining
opening-degree change margin .DELTA.LEVsc by refrigerant
dryness-degree on the outlet side of the supercooling heat
exchanger 28"
[0032] (A) The controller 60 estimates the current dryness-degree
Xmo from the detected current opening-degree LEV0, the operation
frequency of the inverter device of the compressor 3, the
condensation temperature, the evaporation temperature, and the
liquid-pipeline temperature.
[0033] This dryness-degree Xmo is calculated in advance from
experimental values as a function of the operation frequency, the
condensation temperature, the evaporation temperature, and the
liquid pipeline temperature. The calculating method is as follows,
for example:
Xmo=.alpha..times.operation frequency+.beta..times.condensation
temperature+.gamma..times.evaporation temperature+.mu..times.liquid
pipeline temperature
[0034] where .alpha., .beta., .gamma., and .mu. are constants.
[0035] Then, the opening-degree change margin .DELTA.LEVsc is
acquired by the following equation, for example:
.DELTA.LEVsc=B.times.(Xmo-Xmom)
[0036] Here, B is a coefficient acquired from experiments or the
like and Xmom is target dryness-degree (=1).
[0037] As obvious from the above equation, if the current
dryness-degree Xmo is far away from the target dryness-degree Xmom,
the absolute value of the opening-degree change margin .DELTA.LEVsc
becomes larger, while if the value gets close to the target
dryness-degree Xmom, the absolute value of the opening-degree
change margin .DELTA.LEVsc becomes small.
[0038] At this Step S7, the controller 60 further calculates the
LEV opening-degree change margin .DELTA.LEVTd for preventing
discharge temperature rise. The calculation method at this time is
the following calculation method (2):
[0039] Calculation method (2): "Method of determining
opening-degree change margin .DELTA.LEVTd for preventing a rise in
a discharge temperature"
[0040] In this method, if a discharge temperature which should not
be exceeded is set at 120.degree. C., the opening-degree change
margin .DELTA.LEVTd is acquired by the following equation, for
example:
.DELTA.LEVTd=C/(120-Td0)
[0041] where, C is a coefficient acquired from experiments and the
like, and Td0 is a detected value of the discharge temperature.
[0042] As is known from the above equation, as the discharge
temperature Td0 gets close to 120.degree. C., the opening-degree
.DELTA.LEVTd becomes larger.
[0043] At the subsequent Step S8, the controller 60 compares the
respectively calculated opening-degree .DELTA.LEVTd with the
opening-degree .DELTA.LEVsc and the larger value is outputted as an
instruction value of the opening-degree change margin .DELTA.LEV to
the driver of the supercooling throttle valve 49. However, in the
case of the opening-degree LEV0>opening-degree Lmaxsc, the
opening-degree change margin .DELTA.LEVTd is outputted as the
opening-degree change margin .DELTA.LEV. At Step S9, the controller
60 sets the value obtained by adding the opening-degree change
margin .DELTA.LEV to the current opening-degree LEV0 as the
opening-degree LEV to be outputted next time.
LEV=LEV0+.DELTA.LEV
[0044] The control mode described above aims that the discharge
temperature of the compressor 3 is brought to an allowable value or
less and that a supercooling amount of a condensed liquid
refrigerant is controlled in order to realize an operation with
good refrigerating efficiency. That is, after comparing the valve
opening-degree required for the supercooling throttle valve 49 in
order to keep the discharge temperature of the compressor 3 at the
allowable value or less and the valve opening-degree of the
supercooling throttle valve 49 in order to realize an operation
with required and sufficient supercooling-degree and the best
efficiency, the larger opening-degree is outputted to the
supercooling throttle valve 49. Here, the most efficient operation
is an operation when the dryness-degree Xmo of the refrigerant on
the outlet side of the supercooling heat exchanger 28 in the return
circuit 29 becomes 1 (See FIG. 4(a)). On the other hand, if the
discharge temperature needs to be lowered due to a high compression
ratio condition or the like, the operation becomes wet control with
the dryness-degree Xmo less than 1 (See FIG. 4(c)), and then
although the refrigerating efficiency is slightly lowered,
reliability can be maintained by lowering the discharge temperature
to the allowable temperature or less. Also, in a case of an
operation with a low discharge temperature, as setting priority on
efficiency, the LEV opening-degree is controlled to be a target
that is the dryness-degree Xmo=1.
[0045] As described above, in the refrigerator of Embodiment 1,
from operation state data such as the operation frequency detected
by the operation state detecting means 61 of the controller 60, the
condensation temperature by the high-pressure sensor 65, the
evaporation temperature by the low-pressure sensor 66, and the
intake gas refrigerant temperature from the temperature sensor 70,
the dryness-degree Xmo of the refrigerant on the outlet side of the
supercooling heat exchange portion 28 of the return circuit 29
leading to the intermediate-pressure chamber 3A of the compressor 3
is calculated, and the valve opening-degree of the supercooling
throttle valve 49 is controlled so that the calculated
dryness-degree gets close to the value of 1, and thus, supercooling
can be added in the intermediate pressure in the compressor 3. As a
result, coefficient of performance (COP) can be more improved than
the configuration in which supercooling is added to the
low-pressure side of the refrigerant circuit as in the prior-art
technology. Also, as compared with the prior-art technologies,
components of the pipelines and a throttle valve which constitute
an injection circuit and a component such as a control system can
be removed as one system, which simplifies the configuration and
can reduce manufacturing cost.
[0046] Also, according to this refrigerator, three compressor-side
modules 2 having common configurations are used, and their first
base frames 37 are connected to the second base frames 40 of the
liquid-collection-side modules 1. That is, by determining the
number of the compressor-side modules 2 to be used as appropriate
and by connecting the determined number of compressor-side modules
2 to the liquid-collection-side modules 1, a refrigerator according
to a desired refrigerator capacity can be manufactured. Also, since
the compressor-side module 2 has a common configuration, a
production lot can be increased, which enables reduction of
manufacturing cost of a refrigerator. Moreover, since a set of the
return circuit 29, the supercooling heat exchange portion 28, and
the supercooling throttle valve 49 disposed in each of the parallel
pipelines 13, 13, and 13 has a common configuration, the production
lot can be also increased by them, which enables reduction in
manufacturing cost of the refrigerator.
[0047] Also, since the first connecting members 33, 33, and 33, the
second connecting members 34, 34, and 34, the third connecting
members 35, 35, and 35, and the fourth connecting members 53, 53,
and 53 are provided, by operating these connecting members 33, 34,
35, and 53, the refrigerant pipeline 26, the refrigerant pipeline
7, the return circuit 29, and the oil equalizing pipeline 51 can be
divided in the middle, respectively, and maintenance and repair can
be achieved by removing the compressor-side module 2 from the
entire refrigerator condensation unit.
Embodiment 2
[0048] In a refrigerator according to Embodiment 2, as shown in
FIG. 1, on the refrigerant inlet side of the supercooling heat
exchange portion 28 in each return circuit 29, a temperature sensor
(an example of a supercooling-inlet-side refrigerant temperature
detecting means) 68 that detects a refrigerant temperature of that
portion is disposed, respectively. Also, on the refrigerant outlet
side of the supercooling heat exchange portion 28 in each return
circuit 29, a temperature sensor (an example of supercooling outlet
side refrigerant temperature detecting means) 69 that detects a
refrigerant temperature of that portion is disposed,
respectively.
[0049] Control of Embodiment 2 is executed by the controller 60
used in Embodiment 1 in accordance with a control flow in FIG. 3.
However, the calculating method (1) at Step S7 is different from
that of Embodiment 1, and the following method (B) is used instead
of (A) in Embodiment 1.
[0050] (B) The controller 60 controls the valve opening-degree of
the supercooling valve 49 so that a difference between the detected
temperature of the temperature sensor 68 on the inlet side of the
supercooling heat exchanger 28 in the return circuit 29 and the
detected temperature of the temperature sensor 69 on the outlet
side of the supercooling heat exchanger 28 becomes a predetermined
temperature difference (5K, for example). That is, the control in
which the opening-degree change margin .DELTA.LEVsc is calculated
and outputted such that the dryness-degree Xmo gets close to 1 can
be executed by using the detected temperature of the temperature
sensor 68 on the inlet side of the supercooling heat exchanger 28
and the detected temperature of the temperature sensor 69 on the
outlet side of the supercooling heat exchanger 28. Since the
dryness-degree Xmo becomes slightly larger than 1 with the above
control (See FIG. 4(b)), the refrigerating efficiency becomes
somewhat lower than that in the control in (A), but it does not
disturbs the operation.
Embodiment 3
[0051] In Embodiment 1 and Embodiment 2, the refrigerator in which
the three compressor-side modules 2, 2, and 2 are connected onto
the upper face of the liquid-collection-side module 1, but the
present invention is not limited by that. For example, as shown in
FIG. 5(a), a refrigerator in which the two compressor-side modules
2 and 2 are connected to the upper face of a liquid-collection-side
module 1a, which is smaller than the liquid-collection-side module
1 in the horizontal direction, is also included in the present
invention.
Embodiment 4
[0052] Alternatively, as shown in FIG. 5(b), a refrigerator in
which the one compressor-side module 2 is connected onto the upper
face of a liquid-collection-side module 1b, which is further
smaller than the liquid-collection-side module 1a, is also included
in the present invention.
REFERENCE SIGNS LIST
[0053] 1 liquid-collection-side module, 2 compressor-side module, 3
compressor, 3A intermediate-pressure chamber, 6 condenser, 10
liquid container, 13 parallel pipeline, 17 refrigerant pipeline, 18
connecting pipe portion, 19 refrigerant pipeline, 20 throttle
valve, 21 evaporator, 28 supercooling heat exchange portion, 29
return circuit, 49 supercooling throttle valve, 60 controller, 61
operation state detecting means, 62 dryness-degree calculating
means, 63 operation capacity detecting means, 64 supercooling
throttle valve control means, 65 high-pressure sensor (condensation
temperature detecting means), 66 low-pressure sensor (evaporation
temperature detecting means), 67 temperature sensor
(liquid-refrigerant temperature detecting means), 68 temperature
sensor (supercooling-inlet-side refrigerant temperature detecting
means), 69 temperature sensor (supercooling-outlet-side refrigerant
temperature detecting means).
* * * * *