TECHNICAL FIELD
[0001] The present invention relates to a method of identifying a refrigerant leakage spot.
BACKGROUND ART
[0002] In a device having a refrigerant circuit, leakage of refrigerant can occur for reasons
such as damage to the pipe and degradation of components. In such a case, it is necessary
to quickly detect that a refrigerant leakage has occurred from the standpoint of ensuring
the safety of humans. Previously, the following method has been proposed as a method
of detecting a refrigerant leakage.
[0003] Patent Document 1 (Japanese Laid-open Patent Publication No.
2014-95514) proposes a method of determining whether or not there is a leakage of a refrigerant
by detecting, in a refrigerant circuit that includes a receiver, the height of the
liquid level in the receiver after performing a refrigerant collection operation that
collects the refrigerant in the receiver, and finding the amount of filled refrigerant
to be insufficient by comparing the detected liquid level height and a predetermined
reference value.
[0004] Also, Patent Document 2 (Japanese Laid-open Patent Publication No.
2011-226704) proposes a method of determining whether or not there is a leakage of a refrigerant
by detecting, in a refrigerant circuit that includes a supercooling heat exchanger,
the amount of filled refrigerant to be insufficient on the basis of the state (e.g.
supercooling degree or the like) of the refrigerant at the outlet of the supercooling
heat exchanger.
[0005] In addition, Patent Document 3 (Japanese Laid-open Patent Publication No.
2013-40730) proposes a method of identifying the fact that a refrigerant leakage has occurred
and the utilization unit in which a refrigerant leakage has occurred in a refrigerant
circuit that includes a plurality of utilization units, when a refrigerant leakage
has occurred in any of the utilization units, by disposing a refrigerant leakage sensor
capable of detecting a refrigerant leakage in each of the utilization units.
SUMMARY OF THE INVENTION
<Technical Problem>
[0006] Depending on the installation environment of the apparatus, when a refrigerant leakage
has occurred, minimizing the number of repair steps, a quick restoration, and clarification
of the leakage cause and the spot of responsibility becomes necessary. For this reason,
it is necessary to quickly identify not only the fact that a refrigerant leakage has
occurred but also the spot where the refrigerant leakage has occurred.
[0007] However, while it is possible to determine with the methods disclosed in Patent Document
1 and Patent Document 2 the fact that a refrigerant leakage has occurred, it is not
possible to concretely identify the spot where the refrigerant leakage has occurred.
In contrast, the method disclosed in Patent Document 3 can not only identify that
the refrigerant leakage has occurred but also the spot where the refrigerant leakage
has occurred, but since it is necessary to dispose a plurality of refrigerant leakage
sensors, increasing cost becomes a concern.
[0008] The purpose of the present invention is to provide a method of identifying a refrigerant
leakage spot that, when a refrigerant leakage has occurred in a refrigerant circuit,
can identify the spot of the refrigerant leakage while restraining an increase in
cost.
<Solution to Problem>
[0009] A method of identifying a refrigerant leakage spot according to a first aspect of
the present invention is a method that identifies a refrigerant leakage spot when
a leakage of a refrigerant has occurred in a refrigerant circuit including a compressor
and a plurality of valves, each of the valve configured to be capable of being in
a closed state to block the flow of the refrigerant. The method includes a first step
and a second step. The first step is a step for dividing the refrigerant circuit into
a plurality of refrigerant flow paths by setting each of the valves to the closed
state in the state of the compressor being stopped. The second step is a step for
determining whether or not there is a leakage of the refrigerant in the refrigerant
flow paths by detecting a change in the state of the refrigerant in each of the refrigerant
flow paths after the first step.
[0010] In the method of identifying a refrigerant leakage spot according to the first aspect
of the present invention, in the first step the refrigerant circuit is divided into
the plurality of refrigerant flow paths by each of the valves being set to the closed
state in the state of the compressor being stopped, and in the second step the change
in the state of the refrigerant in each of the refrigerant flow paths is detected,
and whether or not there is the leakage of the refrigerant in each of the refrigerant
flow paths is determined. Thereby, the refrigerant circuit is divided into the plurality
of refrigerant flow paths, and whether or not there is a leakage of the refrigerant
in each of the refrigerant flow paths is determined. As a result, it is possible to
identify a refrigerant leakage spot without disposing a plurality of refrigerant leakage
sensors. Hence, when a refrigerant leakage has occurred, the refrigerant leakage spot
can be identified while restraining an increase in cost.
[0011] The "valve" that is used here, one that is capable of blocking the flow of the refrigerant
is suitably selected, with for example a valve that can be controlled to the "closed
state" by switching of the energized state (solenoid valve, motor-operated valve)
and a closing valve that can be manually set to the "closed" state being envisaged.
[0012] The "refrigerant" here is not particularly limited, and for example a slightly flammable
refrigerant such as R32, a refrigerant having flammability such as propane, or a refrigerant
having toxicity such as ammonia is envisaged.
[0013] The "state of the refrigerant" here is not particularly limited provided it is a
variable that can identify the fact that the refrigerant leakage has occurred, and
for example the pressure or temperature of the refrigerant is envisaged.
[0014] A method of identifying a refrigerant leakage spot according to a second aspect of
the present invention is the method of identifying a refrigerant leakage spot according
to the first aspect, in which in the second step, after detecting the state of the
refrigerant in a first refrigerant flow path by a refrigerant state detection sensor,
the valve dividing a second refrigerant flow path from the first refrigerant flow
path is switched from the closed state to an open state, and a change in the state
of the refrigerant in the second refrigerant flow path is detected by detecting a
change in the state of the refrigerant with the refrigerant state detection sensor
in the state of the first refrigerant flow path and the second refrigerant flow path
being in communication with each other. The refrigerant state detection sensor is
a sensor for detecting the state of the refrigerant. The open state is a state in
which the valve allows the flow of the refrigerant. The first refrigerant flow path
is a refrigerant flow path in which the refrigerant state detection sensor is disposed.
The second refrigerant flow path is a refrigerant flow path in which the refrigerant
state detection sensor is not disposed.
[0015] In the method of identifying a refrigerant leakage spot according to the second aspect
of the present invention, in the second step, after detecting the state of the refrigerant
in the first refrigerant flow path by the refrigerant state detection sensor, the
valve that divides the second refrigerant flow path from the first refrigerant flow
path is switched from the closed state to the open state, and the change in the state
of the refrigerant in the second refrigerant flow path is detected by detecting the
change in the state of the refrigerant with the refrigerant state detection sensor
in the state of the first refrigerant flow path and the second refrigerant flow path
being in communication with each other. Thereby, it is possible to detect the state
of the refrigerant in the second refrigerant flow path in which the refrigerant state
detection sensor is not disposed. As a result, it is possible to identify a refrigerant
leakage spot even without disposing a refrigerant state detection sensor in each refrigerant
flow path. Hence, when a refrigerant leakage has occurred, the refrigerant leakage
spot can be identified while further restraining an increase in cost.
[0016] The "refrigerant state detection sensor" here, for example a pressure sensor that
detects the pressure of the refrigerant or a temperature sensor that detects the temperature
of the refrigerant is envisaged.
[0017] A method of identifying a refrigerant leakage spot according to a third aspect of
the present invention is the method of identifying a refrigerant leakage spot according
to the first aspect or the second aspect of the present invention, in which the first
step includes a refrigerant collection step. The refrigerant collection step is a
step for driving the compressor to collect a portion of the refrigerant in the refrigerant
circuit into a container capable of storing the refrigerant. In the first step, after
the completion of the refrigerant collection step, each of the valves is switched
to the closed state after stopping the compressor so as to divide the refrigerant
circuit into the plurality of refrigerant flow paths. Thereby, after collecting the
refrigerant into the container, it is possible to detect a change in the state of
the gas refrigerant that exists in each refrigerant flow path. That is, in the second
step, it becomes possible to detect a change in the state of the gas refrigerant,
in which the change in state is more noticeable than that of the liquid refrigerant
in a case when a refrigerant leakage has occurred. Hence, it is possible to perform
the determination with high precision.
[0018] A method of identifying a refrigerant leakage spot according to a fourth aspect of
the present invention is the method of identifying a refrigerant leakage spot according
to any one of the first aspect to the third aspect of the present invention, in which
the first step is performed on the occasion of, in a filled refrigerant amount determination
operation, the filled refrigerant amount being determined to be unsuitable, or a refrigerant
leakage sensor having detected a refrigerant leakage. The filled refrigerant amount
determination operation is an operation for determining the suitability of the filled
refrigerant amount in the refrigerant circuit. The refrigerant leakage sensor is a
sensor that detects the leakage of the refrigerant in the refrigerant circuit.
[0019] Thereby, the first step and the second step are performed after it has been determined
that the filled refrigerant amount in the refrigerant circuit is insufficient. That
is, the first step and the second step are performed with the main purpose of identifying
the refrigerant leakage spot when a refrigerant leakage has occurred, and are not
performed with the main purpose of detecting the fact that the refrigerant leakage
has occurred. Therefore, the need can be eliminated to stop the compressor each time
when determining whether or not there is the leakage of the refrigerant, and so degradation
of components that are subject to temperature control is reduced, or a decrease in
comfort is restrained.
[0020] The "refrigerant leakage sensor" here is a sensor for detecting the refrigerant that
has leaked, and for example detects a refrigerant leakage by detecting a change in
the electrical resistance value in accordance with the concentration of the leaked
refrigerant. That is, the "refrigerant leakage sensor" differs from the "refrigerant
state detection sensor" that detects the state of the refrigerant.
[0021] A method of identifying a refrigerant leakage spot according to a fifth aspect of
the present invention is the method of identifying a refrigerant leakage spot according
to any one of the first aspect to the fourth aspect of the present invention, in which
in the second step, an information output apparatus is made to output information
that reports about the refrigerant flow path in which a refrigerant leakage is determined
to have occurred. The information output apparatus is an apparatus that outputs information.
[0022] Thereby, when a refrigerant leakage has occurred, information that identifies the
spot where the refrigerant leakage has occurred is output from the information output
apparatus. As a result, when the leakage of the refrigerant has occurred, it becomes
easy for the user to recognize the fact that the leakage of the refrigerant has occurred
and the spot where the leakage of the refrigerant has occurred, and the user is prompted
to take action. Hence, safety with regard to refrigerant leakages is enhanced.
<Advantageous Effects of Invention>
[0023] In the method of identifying a refrigerant leakage spot according to the first aspect
of the present invention, the refrigerant circuit is divided into the plurality of
refrigerant flow paths, and whether or not there is a leakage of the refrigerant in
each refrigerant flow path is determined. As a result, the refrigerant leakage spot
can be identified without disposing the plurality of refrigerant leakage sensors.
Hence, a refrigerant leakage spot can be identified when a refrigerant leakage has
occurred while restraining an increase in cost.
[0024] In the method of identifying a refrigerant leakage spot according to the second aspect
of the present invention, it becomes possible to detect the state of the refrigerant
in the second refrigerant flow path in which the refrigerant state detection sensor
is not disposed. As a result, the refrigerant leakage spot can be identified without
disposing a refrigerant state detection sensor in each refrigerant flow path. Hence,
a refrigerant leakage spot can be identified when a refrigerant leakage has occurred
while further restraining an increase in cost.
[0025] In the method of identifying a refrigerant leakage spot according to the third aspect
of the present invention, after collecting the refrigerant into the container, it
becomes possible to detect a change in the state of the gas refrigerant that exists
in each refrigerant flow path. That is, in the second step, it becomes possible to
detect the change in the state of the gas refrigerant, in which the change in state
is more noticeable than that of the liquid refrigerant in a case when a refrigerant
leakage has occurred. Hence, it is possible to perform the determination with high
precision.
[0026] In the method of identifying a refrigerant leakage spot according to the fourth aspect
of the present invention, the first step and the second step are performed in the
state of the filled refrigerant amount in the refrigerant circuit having been determined
to be insufficient. That is, the first step and the second step are performed with
the main purpose of identifying the refrigerant leakage spot when the refrigerant
leakage has occurred, and are not performed with the main purpose of detecting the
fact that the refrigerant leakage has occurred. Therefore, the need is eliminated
to stop the compressor each time when determining whether or not there is a leakage
of the refrigerant, and so degradation of components that are subject to temperature
control is reduced, or a decrease in comfort is restrained.
[0027] In the method of identifying a refrigerant leakage spot according to the fifth aspect
of the present invention, when a leakage of the refrigerant has occurred, predetermined
reporting information (information identifying the spot where the refrigerant leakage
has occurred) is output. As a result, when the leakage of the refrigerant has occurred,
it becomes easy for the user to recognize the fact that the leakage of the refrigerant
has occurred and the spot where the leakage of the refrigerant has occurred, and the
user is prompted to take action. Hence, safety with regard to refrigerant leakages
is enhanced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028]
FIG. 1 is an outline configuration diagram of a refrigeration apparatus to which a
method of identifying a refrigerant leakage spot according to one embodiment of the
present invention is applied.
FIG. 2 is a diagram that schematically shows a first flow path, a second flow path
and a third flow path included in a refrigerant circuit of the refrigeration apparatus.
FIG. 3 is a block diagram that conceptually shows a controller and each unit connected
to the controller.
FIG. 4 is a flowchart that shows an example of the processing flow of the controller.
FIG. 5 is a flowchart that shows an example of the processing flow of the controller.
FIG. 6 is a sequence diagram that schematically shows the operation of each unit of
the refrigeration apparatus in a mode of determining the amount of filled refrigerant.
FIG. 7 is a sequence diagram that schematically shows the operation of each unit of
the refrigeration apparatus in a mode of determining a refrigerant leakage.
FIG. 8 is an outline configuration diagram of the refrigeration apparatus according
to modification B to which the method of identifying a refrigerant leakage spot according
to one embodiment of the present invention is applied.
FIG. 9 is a diagram that schematically shows a first flow path and a second flow path
included in the refrigerant circuit of the refrigeration apparatus according to modification
B.
DESCRIPTION OF EMBODIMENTS
[0029] Hereinbelow, a method of identifying a refrigerant leakage spot according to one
embodiment of the present invention will be described with reference to the appended
drawings. The embodiments described herein are exemplary of the present invention
and not intended to limit the technical scope of the present invention, with suitable
modifications being possible with a scope that does not depart from the spirit of
the invention.
[0030] The method of identifying a refrigerant leakage spot according to the present embodiment
is applied to a refrigeration apparatus 100.
(1) Refrigeration apparatus 100
[0031] FIG. 1 is an outline configuration diagram of the refrigeration apparatus 100 to
which the method of identifying a refrigerant leakage spot according to one embodiment
of the present invention is applied. The refrigeration apparatus 100 is an apparatus
that, using a vapor compression type refrigeration cycle, performs cooling of the
utilization-side space in the compartment of a refrigerating warehouse or a store
showcase. The refrigeration apparatus 100 mainly has a heat source unit 10, a utilization
unit 30, a liquid refrigerant communication pipe L1 that connects the heat source
unit 10 to the utilization unit 30, a gas refrigerant communication pipe G1, a plurality
of remote controllers 40 as input devices and display devices, and a controller 50
that controls the operation of the refrigeration apparatus 100.
[0032] In the refrigeration apparatus 100, a refrigerant circuit RC is constituted by the
heat source unit 10 and the utilization unit 30 being connected via the liquid refrigerant
communication pipe L1 and the gas refrigerant communication pipe G1. In the refrigeration
apparatus 100, a refrigeration cycle is performed in which the refrigerant enclosed
in the refrigerant circuit RC is compressed, cooled or condensed, decompressed, heated
or evaporated, and afterwards again compressed. In the present embodiment, R32 is
filled in the refrigerant circuit RC as the refrigerant for performing the vapor compression
type refrigeration cycle.
(1-1) Heat source unit 10
[0033] The heat source unit 10 is connected with the utilization unit 30 via the liquid
refrigerant communication pipe L1 and the gas refrigerant communication pipe G1, and
constitutes a part of the refrigerant circuit RC. The heat source unit 10 mainly has
a compressor 11, a heat source-side heat exchanger 12, a receiver 13, a supercooler
14, a heat source-side expansion valve 15 (expansion mechanism), an injection valve
16, a liquid-side closing valve 17, a gas-side closing valve 18, and a check valve
19.
[0034] Also, the heat source unit 10 has a first heat source-side gas refrigerant pipe P1
that connects the discharge side of the compressor 11 and the gas-side end of the
heat source-side heat exchanger 12, a heat source-side liquid refrigerant pipe P2
that connects the liquid-side end of the heat source-side heat exchanger 12 and the
liquid refrigerant communication pipe L1, and a second heat source-side gas refrigerant
pipe P3 that connects the intake side of the compressor 11 and the gas refrigerant
communication pipe G1.
[0035] In addition, the heat source unit 10 has an injection pipe P4 that branches off a
portion of the refrigerant flowing through the heat source-side liquid refrigerant
pipe P2 for return to the compressor 11. The injection pipe P4 branches off from the
downstream-side part of the supercooler 14 in the heat source-side liquid refrigerant
pipe P2 and, after passing through the supercooler 14, is connected midway in the
compression stroke of the compressor 11.
[0036] The compressor 11 is a device that compresses low-pressure refrigerant in the refrigeration
cycle until reaching a high pressure. Here, a compressor with a sealed-type structure
in which a volume-type compression element (not illustrated), such as a rotary-type
or scroll type, is rotatably driven by a compressor motor M11, is used as the compressor
11. Here, control of the operation frequency of the compressor motor M11 is possible
with an inverter, whereby capacity control of the compressor 11 becomes possible.
[0037] The heat source-side heat exchanger 12 is a heat exchanger that functions as a radiator
or condenser of high-pressure refrigerant in the refrigeration cycle. Here, the heat
source unit 10 has a heat source-side fan 20 for drawing air outside the refrigeration
compartment (heat source-side air) within the heat source unit 10, and after being
heat-exchanged with the refrigerant in the heat source-side heat exchanger 12, discharging
the air to the outside. That is, the heat source unit 10 has the heat source-side
fan 20 as a fan that supplies to the heat source-side heat exchanger 12 the heat source-side
air as a cooling source of the refrigerant flowing through the heat source-side heat
exchanger 12. The heat source-side fan 20 is rotatably driven by the heat source-side
fan motor M20.
[0038] The receiver 13 is a container that temporarily collects the refrigerant condensed
in the heat source-side heat exchanger 12, and is arranged in the heat source-side
liquid refrigerant pipe P2.
[0039] The supercooler 14 is a heat exchanger that further cools the refrigerant temporarily
collected in receiver 13, and is arranged at the downstream-side part of the receiver
13 in the heat source-side liquid refrigerant pipe P2.
[0040] The heat source-side expansion valve 15 (valve) is a motor-operated expansion valve
in which opening control is possible, and is arranged at the downstream-side part
of the supercooler 14 in the heat source-side liquid refrigerant pipe P2.
[0041] The injection valve 16 is arranged at the part of the injection pipe P4 prior to
reaching the inlet of the supercooler 14. The injection valve 16 is a motor-operated
expansion valve in which opening control is possible. Depending on the opening degree,
the injection valve 16 decompresses the refrigerant flowing through the injection
pipe P4 prior to being made to flow into the supercooler 14. In this way, the supercooler
14 is configured to cool the refrigerant temporarily collected in receiver 13, with
the refrigerant branched off from the heat source-side liquid refrigerant pipe P2
via the injection pipe P4 serving as the cooling source.
[0042] The liquid-side closing valve 17 (valve) is a manual valve arranged at the connection
part between the heat source-side liquid refrigerant pipe P2 and the liquid refrigerant
communication pipe L1. One end of the liquid-side closing valve 17 is connected to
the heat source-side liquid refrigerant pipe P2, and the other end is connected to
the liquid refrigerant communication pipe L1. When the liquid-side closing valve 17
is set to the open state, the heat source-side liquid refrigerant pipe P2 and the
liquid refrigerant communication pipe L1 are allowed to communicate, and when set
to the closed state, the liquid-side closing valve 17 cuts off the communication between
the heat source-side liquid refrigerant pipe P2 and the liquid refrigerant communication
pipe L1. The liquid-side closing valve 17 is normally set to the open state.
[0043] The gas-side closing valve 18 (valve) is a manual valve that is arranged at the connection
part between the second heat source-side gas refrigerant pipe P3 and the gas refrigerant
communication pipe G1. One end of the gas-side closing valve 18 is connected to the
second heat source-side gas refrigerant pipe P3, and the other end is connected to
the gas refrigerant communication pipe G1. When the gas-side closing valve 18 is set
to the open state, the second heat source-side gas refrigerant pipe P3 and the gas
refrigerant communication pipe G1 are allowed to communicate, and when set to the
closed state, the gas-side closing valve 18 cuts off the communication between the
second heat source-side gas refrigerant pipe P3 and the gas refrigerant communication
pipe G1. The gas-side closing valve 18 is normally set to the open state.
[0044] The check valve 19 is arranged in the heat source-side liquid refrigerant pipe P2.
More specifically, the check valve 19 is arranged on the outlet side of the heat source-side
heat exchanger 12 and the inlet side of the receiver 13. The check valve 19 allows
the flow of refrigerant from the outlet side of the heat source-side heat exchanger
12 and blocks the flow of refrigerant from the inlet side of the receiver 13.
[0045] Various sensors that are electrically connected to a heat-source-unit control unit
26 are arranged in the heat source unit 10. Specifically, an intake pressure sensor
21 (refrigerant state detection sensor) that detects an intake pressure LP, which
is the pressure of the refrigerant on the intake side of the compressor 11, and a
discharge pressure sensor 22 (refrigerant state detection sensor) that detects a discharge
pressure HP, which is the pressure of the refrigerant on the discharge side of the
compressor 11, are arranged in the vicinity of the compressor 11 in the heat source
unit 10. Also, a receiver outlet temperature sensor 23 that detects a receiver outlet
temperature TL, which is the temperature of the refrigerant at the outlet of the receiver
13, is arranged in the heat source-side liquid refrigerant pipe P2, in the part between
the outlet of the receiver 13 and the inlet of the supercooler 14. Moreover, a heat
source-side air sensor 24 that detects a temperature Ta of the heat source-side air
drawn into the heat source unit 10 is arranged in the vicinity of the heat source-side
heat exchanger 12 or the heat source-side fan 20. A liquid level detection sensor
25 that detects a liquid level height Lh, which is the height of the liquid level
of the liquid refrigerant accommodated in the receiver, is arranged in the receiver
13.
[0046] The heat source unit 10 has the heat-source-unit control unit 26 that controls the
operation of each of the elements constituting the heat source unit 10. The heat-source-unit
control unit 26 has a microcomputer containing a CPU, memory, and the like. The heat-source-unit
control unit 26 is connected via a communication line cb1 with a utilization-unit
control unit 38 of each utilization unit 30, and thereby performs sending and receiving
of control signals.
(1-2) Utilization unit 30
[0047] The utilization unit 30 is connected with the heat source unit 10 via the liquid
refrigerant communication pipe L1 and the gas refrigerant communication pipe G1, and
constitutes a part of the refrigerant circuit RC.
[0048] The utilization unit 30 has a heating pipe 31, a utilization-side expansion valve
32, a utilization-side heat exchanger 33 (evaporator), and a drain pan 34. The utilization
unit 30 also has a first utilization-side liquid refrigerant pipe P5 that connects
the liquid refrigerant communication pipe L1 and the utilization-side expansion valve
32, a second utilization-side liquid refrigerant pipe P6 that connects the liquid
side end of the utilization-side heat exchanger 33 and the utilization-side expansion
valve 32, and a utilization-side gas refrigerant pipe P7 that connects the gas-side
end of the utilization-side heat exchanger 33 and the gas refrigerant communication
pipe G1.
[0049] The heating pipe 31 is a refrigerant pipe through which passes high-pressure liquid
refrigerant sent from the heat source unit 10. The heating pipe 31 is a pipe for melting
ice mass generated by the freezing of the drain water in the drain pan 34, and is
thermally connected to the drain pan 34. The heating pipe 31 is contained in the first
utilization-side liquid refrigerant pipe P5.
[0050] The utilization-side expansion valve 32 (valve) is a diaphragm mechanism that functions
as a decompression means (expansion means) for the high-pressure refrigerant sent
from the heat source unit 10. The utilization-side expansion valve 32 is an opening
adjustable motor-operated valve of which the opening changes depending on the supply
of a predetermined drive voltage. One end of the utilization-side expansion valve
32 is connected to the first utilization-side liquid refrigerant pipe P5, and the
other end is connected to the second utilization-side liquid refrigerant pipe P6.
When the utilization-side expansion valve 32 is set to the minimum opening (closed
state), the flow of refrigerant is blocked between the first utilization-side liquid
refrigerant pipe P5 and the second utilization-side liquid refrigerant pipe P6.
[0051] The utilization-side heat exchanger 33 is a heat exchanger that functions as an evaporator
of low-pressure refrigerant in the refrigeration cycle to cool the in-compartment
air (utilization-side air). Here, the utilization unit 30 has a utilization-side fan
36 for drawing the utilization-side air in the utilization unit 30 and, after being
heat-exchanged with the refrigerant in the utilization-side heat exchanger 33, supplying
the air to the utilization-side space. That is, the utilization unit 30 has the utilization-side
fan 36 as a fan that supplies to the utilization-side heat exchanger 33 the utilization-side
air serving as a heating source for refrigerant flowing through the utilization-side
heat exchanger 33. In the utilization unit 30 in the operating state, the utilization-side
fan 36 is rotatably driven by an utilization-side fan motor M36.
[0052] The drain pan 34 receives and collects the drain water generated in the utilization-side
heat exchanger 33. The drain pan 34 is disposed below the utilization-side heat exchanger
33.
[0053] In addition, the utilization unit 30 has the utilization-unit control unit 38 that
controls the operation of each of the elements constituting the utilization unit 30.
The utilization-unit control unit 38 has a microcomputer containing a CPU, memory,
and the like. The utilization-unit control unit 38 is connected via the communication
line cb1 with the heat-source-unit control unit 26, and thereby performs sending and
receiving of control signals.
(1-3) Remote controller 40 (information output part)
[0054] The remote controller 40 is an input device for a user to input various commands
for switching the operation state of the refrigeration apparatus 100. For example,
commands for starting and stopping of the refrigeration apparatus 100 and switching
the set temperature are input to the remote controller 40 by the user. Various commands
are input by the user in a refrigerant leakage determination mode (described below)
using the remote controller 40.
[0055] For example, the user inputs to the remote controller 40 a command (closing valve
close notification command) for notifying the controller 50 that both the liquid-side
closing valve 17 and the gas-side closing valve 18 have been switched to the closed
state. Also, the user inputs to the remote controller 40 a command (liquid-side closing
valve open notification command) for notifying the controller 50 that the liquid-side
closing valve 17 has been switched to the open state. The user also inputs to the
remote controller 40 a command (gas-side closing valve open notification command)
for notifying the controller 50 that the gas-side closing valve 18 has been switched
to the open state.
[0056] The closing valve close notification command, the liquid-side closing valve open
notification command, and the gas-side closing valve open notification command are
commands for prompting the start of a refrigerant leakage spot identifying process
(described below) in the controller 50.
[0057] The remote controller 40 also functions as a display device for displaying a variety
of information to the user. For example, the remote controller 40 displays the operational
status (set temperature and the like) of the refrigeration apparatus 100. Also, the
remote controller 40, in the refrigerant leakage determination mode, displays closing
valve close switching request information (described below) that requests the user
to switch the liquid-side closing valve 17 and the gas-side closing valve 18 to the
closed state; liquid-side closing valve open switching request information (described
below) that requests the user to switch the liquid-side closing valve 17 to the open
state; and gas-side closing valve open switching request information (described below)
that requests the user to switch the gas-side closing valve 18 to the open state.
[0058] The remote controller 40 is connected with the utilization-unit control unit 38 via
the communication line, with signal transmission and reception performed mutually
therebetween. The remote controller 40 transmits commands input by the user to the
utilization-unit control unit 38 via the communication line. The remote controller
40 also displays information in accordance with instructions received via the communication
line.
(1-4) Controller 50
[0059] In the refrigeration apparatus 100, the heat-source-unit control unit 26 and each
utilization-unit control unit 38 are connected via the communication line cb1, whereby
the controller 50, which controls the operation of the refrigeration apparatus 100,
is constituted. The controller 50 will be described in detail in "(4) Details of controller
50" given later.
(2) Flow of refrigerant in the refrigerant circuit RC during cooling operation
[0060] Hereinbelow, the flow of the refrigerant in the refrigerant circuit RC during in
each operation mode will be described. During running of the refrigeration apparatus
100, a cooling operation (refrigeration cycle operation) is performed in which the
refrigerant that is filled in the refrigerant circuit RC circulates mainly in the
order of the compressor 11, the heat source-side heat exchanger 12 (radiator), the
receiver 13, the supercooler 14, the heat source-side expansion valve 15 (expansion
mechanism), the utilization-side expansion valve 32, and the utilization-side heat
exchanger 33 (evaporator). In this cooling operation, a portion of the refrigerant
that flows through the heat source-side liquid refrigerant pipe P2 is branched off
via the injection pipe P4 and, after passing through the supercooler 14, is returned
to the compressor 11.
[0061] When the cooling operation is started, the refrigerant in the refrigerant circuit
RC is drawn into the compressor 11, compressed and then discharged. Low pressure in
the refrigeration cycle is the intake pressure LP that is detected by the intake pressure
sensor 21, and high pressure in the refrigeration cycle is the discharge pressure
HP that is detected by the discharge pressure sensor 22.
[0062] In the compressor 11, capacity control according to the cooling load required in
the utilization unit 30 is performed. Specifically, a target value of the intake pressure
LP is set in accordance with the cooling load required in the utilization unit 30,
and the operation frequency of the compressor 11 is controlled so that the intake
pressure LP becomes the target value. The gas refrigerant discharged from the compressor
11 flows into the gas side end of the heat source-side heat exchanger 12 via the first
heat source-side gas refrigerant pipe P1.
[0063] The gas refrigerant that has flowed into the gas-side end of the heat source-side
heat exchanger 12 undergoes heat exchange with heat source-side air supplied by the
heat source-side fan 20, whereby heat is released, and condensation occurs resulting
in liquid refrigerant in a supercooled state that flows out from the liquid-side end
of the heat source-side heat exchanger 12.
[0064] The liquid refrigerant that has flowed out from the liquid-side end of the heat source-side
heat exchanger 12 passes the part of the heat source-side liquid refrigerant pipe
P2 extending from the heat source-side heat exchanger 12 to the receiver 13, and flows
into the inlet of the receiver 13. The liquid refrigerant that has flowed into the
receiver 13, after being temporarily accumulated as a liquid refrigerant in a saturated
state in the receiver 13, flows out from the outlet of the receiver 13. Here, the
temperature of the refrigerant at the outlet of the receiver 13 is the receiver outlet
temperature TL detected by the receiver outlet temperature sensor 23.
[0065] The liquid refrigerant that has flowed out from the outlet of the receiver 13 passes
the part of the heat source-side liquid refrigerant pipe P2 extending from the receiver
13 to the supercooler 14 and flows into the inlet of the supercooler 14 on the heat
source-side liquid refrigerant pipe P2 side.
[0066] In the supercooler 14, the liquid refrigerant that has flowed into the supercooler
14 is further cooled by undergoing heat exchange with the refrigerant flowing through
the injection pipe P4 to become liquid refrigerant in a supercooled state, which flows
out from the outlet of the supercooler 14 on the heat source-side liquid refrigerant
pipe P2 side.
[0067] The liquid refrigerant that has flowed out from the outlet of the supercooler 14
on the heat source-side liquid refrigerant pipe P2 side passes the part of the heat
source-side liquid refrigerant pipe P2 between the supercooler 14 and the heat source-side
expansion valve 15 to flow into the heat source-side expansion valve 15. At this time,
a portion of the liquid refrigerant that has flowed out from the outlet of the supercooler
14 on the heat source-side liquid refrigerant pipe P2 side is branched off to the
injection pipe P4 from the part of the heat source-side liquid refrigerant pipe P2
between the supercooler 14 and the heat source-side expansion valve 15.
[0068] The refrigerant flowing through the injection pipe P4 is decompressed to an intermediate
pressure in the refrigeration cycle by the injection valve 16. The refrigerant flowing
through the injection pipe P4 after being decompressed by the injection valve 16 flows
into the inlet of the supercooler 14 on the injection pipe P4 side. The refrigerant
that has flowed into the inlet of the supercooler 14 on the injection pipe P4 side
undergoes heat exchange in the supercooler 14 with the refrigerant flowing through
the heat source-side liquid refrigerant pipe P2 and is thereby heated to become gas
refrigerant. The refrigerant heated in the supercooler 14 flows out from the outlet
of the supercooler 14 on the injection pipe P4 side and is returned to the compressor
11 midway in the compression stroke.
[0069] The liquid refrigerant that has flowed from the heat source-side liquid refrigerant
pipe P2 into the heat source-side expansion valve 15, after being decompressed by
the heat source-side expansion valve 15, flows into the utilization unit 30 via the
liquid-side closing valve 17 and the liquid refrigerant communication pipe L1.
[0070] The refrigerant that has flowed into the utilization unit 30 flows into the utilization-side
expansion valve 32 by way of the first utilization-side liquid refrigerant pipe P5
(heating pipe 31). The refrigerant that has flowed into the utilization-side expansion
valve 32 is decompressed to a low pressure in the refrigeration cycle by the utilization-side
expansion valve 32, and then flows into the liquid-side end of the utilization-side
heat exchanger 33 via the second utilization-side liquid refrigerant pipe P6.
[0071] The refrigerant that has flowed into the liquid-side end of utilization-side heat
exchanger 33 undergoes heat exchange in the utilization-side heat exchanger 33 with
utilization-side air supplied by the utilization-side fan 36 and evaporates into gas
refrigerant that then flows out from the gas-side end of the utilization-side heat
exchanger 33.
[0072] The gas refrigerant that flowed out from the gas-side end of the utilization-side
heat exchanger 33 is again drawn into the compressor 11 by way of the utilization-side
gas refrigerant pipe P7, the gas refrigerant communication pipe G1, the gas-side closing
valve 18, and the second heat source-side gas refrigerant pipe P3.
(3) Refrigerant flow paths included in refrigerant circuit RC
[0073] FIG. 2 is a diagram that schematically shows a first flow path RP1, a second flow
path RP2, a third flow path RP3 included in the refrigerant circuit RC. As shown in
FIG. 2, the refrigerant circuit RC is mainly divided into the first flow path RP1,
the second flow path RP2, and the third flow path RP3.
[0074] The first flow path RP1 (first refrigerant flow path) is a refrigerant flow path
constituted in the heat source unit 10 (more precisely, between one end side of the
liquid-side closing valve 17 and one end side of the gas-side closing valve 18). Specifically,
the first flow path RP1 is a refrigerant flow path constituted by the first heat source-side
gas refrigerant pipe P1, the heat source-side liquid refrigerant pipe P2, the second
heat source-side gas refrigerant pipe P3, and the injection pipe P4. That is, the
first flow path RP1 is a refrigerant flow path that includes the compressor 11, the
heat source-side heat exchanger 12, the receiver 13, the supercooler 14, the heat
source-side expansion valve 15, and the injection valve 16.
[0075] The second flow path RP2 (second refrigerant flow path) is a refrigerant flow path
constituted from a part of the utilization unit 30 to the gas refrigerant communication
pipe G1 (more precisely, between one end side of the utilization-side expansion valve
32 and the other end side of the gas-side closing valve 18). Specifically, the second
flow path RP2 is a refrigerant flow path constituted by the second utilization-side
liquid refrigerant pipe P6, the utilization-side gas refrigerant pipe P7, and the
gas refrigerant communication pipe G1. That is, the second flow path RP2 is a refrigerant
flow path that includes the utilization-side heat exchanger 33.
[0076] The third flow path RP3 (second refrigerant flow path) is a refrigerant flow path
constituted from the liquid refrigerant communication pipe L1 to a part of the utilization
unit 30 (more precisely, between the other end side of the liquid-side closing valve
17 and the other end side of the utilization-side expansion valve 32). Specifically,
the third flow path RP3 is a refrigerant flow path constituted by the liquid refrigerant
communication pipe L1 and the first utilization-side liquid refrigerant pipe P5. That
is, the third flow path RP3 is a refrigerant flow path that includes the heating pipe
31.
[0077] That is, the refrigerant circuit RC is divided into the plurality of refrigerant
flow paths (RP1, RP2, and RP3) by each of the valves (specifically, the liquid-side
closing valve 17, the gas-side closing valve 18, and the utilization-side expansion
valve 32) being set to the closed state.
(4) Details of controller 50
[0078] In the refrigeration apparatus 100, the controller 50 is constituted by the heat-source-unit
control unit 26 and the utilization-unit control unit 38 being connected by a communication
line. FIG. 3 is a block diagram that conceptually shows the controller 50 and each
unit connected to the controller 50.
[0079] The controller 50 has a plurality of control modes and controls the operation of
the refrigeration apparatus 100 in accordance with the control mode which has been
changed to. In the present embodiment, the controller 50 has as control modes a normal
operation mode that is usually changed to, a filled refrigerant amount determination
mode that is changed to when determining the suitability of the amount of filled refrigerant
(whether or not there is the leakage of the refrigerant), and a refrigerant leakage
determination mode that is changed to when the refrigerant leakage has occurred.
[0080] The controller 50 is electrically connected with each of actuators (specifically
the compressor 11 (compressor motor M11), the heat source-side expansion valve 15,
the injection valve 16, and the heat source-side fan 20 (heat source side fan motor
M20)) and the various sensors (the intake pressure sensor 21, the discharge pressure
sensor 22, the receiver outlet temperature sensor 23, the heat source-side air sensor
24 and the liquid level detection sensor 25), the actuators and sensors being included
in the heat source unit 10. In addition, the controller 50 is electrically connected
with the actuators included in the utilization unit 30 (specifically, the utilization-side
fan 36 (utilization-side fan motor M36). The controller 50 is also electrically connected
with the remote controller 40.
[0081] The controller 50 mainly has a storage unit 51, a communication unit 52, a mode control
unit 53, an actuator control unit 54, a filled refrigerant amount shortage discriminating
unit 55, a display control unit 56, and a refrigerant leakage spot identifying unit
57. These units in the controller 50 are realized by the parts included in the heat-source-unit
control unit 26 and/or the utilization-unit control unit 38 functioning integrally.
(4-1) Storage unit 51
[0082] The storage unit 51 is constituted by for example ROM, RAM, flash memory, and the
like, and includes a volatile storage region and a nonvolatile storage region. A control
program that defines the process in each unit of the controller 50 is stored in the
storage unit 51.
[0083] The storage unit 51 includes a detection value storage region 510 that stores the
detection value of each sensor. For example, the detection value of the intake pressure
sensor 21 (intake pressure LP), the detection value of the discharge pressure sensor
22 (discharge pressure HP), the detection value of the liquid level detection sensor
25 (liquid level height Lh) and the like are stored in the detection value storage
region 510.
[0084] The storage unit 51 includes a reference value storage region 511 that stores a reference
value Sh used in the filled refrigerant amount determination that will be described
below. The reference value Sh is a reference value of the liquid level height in the
receiver 13 after completion of a refrigerant collection operation described below.
The reference value Sh is set beforehand in accordance with the refrigerant amount
filled in the refrigerant circuit RC and the capacity of the receiver 13.
[0085] The storage unit 51 further includes a pressure reference value storage region 512
that stores a pressure reference value table (not illustrated). In the pressure reference
value table, the pressure reference values of the intake pressure and the discharge
pressure are defined by situation in accordance with the detection values of the receiver
outlet temperature sensor 23 and the heat source-side air sensor 24 (TL and Ta), the
refrigerant circulation amount determined from the characteristics of the compressor
11, and the lengths of each refrigerant pipe.
[0086] A plurality of flags having a predetermined number of bits are provided in the storage
unit 51.
[0087] For example, a control mode discrimination flag 513 capable of discriminating the
control mode to which the controller 50 has changed is provided in the storage unit
51. The control mode discrimination flag 513 includes a predetermined number of bits,
so that a predetermined bit is raised in accordance with the control mode that has
been changed to.
[0088] A refrigerant collection completion flag 514 that discriminates whether the refrigerant
collection operation (described below) executed in the refrigerant leakage determination
mode has been completed is provided in the storage unit 51. The refrigerant collection
completion flag 514 is raised when the refrigerant collection operation executed in
the refrigerant leakage determination mode is completed.
[0089] A filled refrigerant amount determination completion flag 515 that discriminates
whether the filled refrigerant amount determination, which determines whether the
refrigerant amount filled in the refrigerant circuit RC is insufficient, has been
completed is provided in the storage unit 51. The filled refrigerant amount determination
completion flag 515 is raised when the filled refrigerant amount determination has
been completed.
[0090] A filled refrigerant amount shortage discrimination flag 516 for discriminating whether
the refrigerant amount filled in the refrigerant circuit RC is insufficient (that
is, whether the filled refrigerant amount when filling refrigerant in the refrigerant
circuit RC is not suitable, or whether a refrigerant leakage has occurred in the refrigerant
circuit RC) is provided in the storage unit 51. The filled refrigerant amount shortage
discrimination flag 516 is raised when the refrigerant amount filled in the refrigerant
circuit RC is insufficient (that is, when the filled refrigerant amount when filling
refrigerant in the refrigerant circuit RC is not suitable, or when a refrigerant leakage
has occurred in the refrigerant circuit RC).
[0091] A identifying process progress flag 517 that indicates the degree of progress of
the refrigerant leakage spot identifying process (described below) executed in the
refrigerant leakage determination mode is provided in the storage unit 51. The identifying
process progress flag 517 includes a predetermined number of bits, so that a predetermined
bit is raised in accordance with the progress situation of the refrigerant leakage
spot identifying process being executed.
[0092] A refrigerant leakage spot discrimination flag 518 that discriminates the refrigerant
leakage spot identified in the refrigerant leakage spot identifying process is provided
in the storage unit 51. The refrigerant leakage spot discrimination flag 518 includes
a predetermined number of bits, so that a predetermined bit is raised in accordance
with the refrigerant leakage spot identified in the refrigerant leakage spot identifying
process.
[0093] A command discrimination flag 519 for discriminating whether a predetermined command
(described below) has been input via the remote controller 40 is provided in the storage
unit 51. The command discrimination flag 519 includes a predetermined number of bits,
so that a corresponding bit is raised when the predetermined command has been input
in accordance with the situation. For example, in the refrigeration leakage determination
mode, when the closing valve close notification command, the liquid-side closing valve
open notification command, and the gas-side closing valve open notification command
input by the user have been received, the bits corresponding to the received commands
are raised in the command discrimination flag 519.
(4-2) Communication unit 52
[0094] The communication unit 52 is a function part that plays the role of a communication
interface for performing transmission and reception of signals with each of the devices
connected to the controller 50. The communication unit 52 receives a request from
the actuator control unit 54 and transmits a predetermined signal to a designated
actuator. The communication unit 52, upon receiving signals output from the sensors
(21 to 25) and the remote controller 40, also performs storage in the corresponding
storage region of the storage unit 51 and raises a predetermined flag.
(4-3) Mode control unit 53
[0095] The mode control unit 53 is a function part that switches the control mode. The mode
control unit 53 raises the control mode discrimination flag 513 in accordance with
the control mode that has been switched to. The mode control unit 53 normally switches
the control mode to the normal operation mode.
[0096] The mode control unit 53 switches the control mode from the normal operation mode
to the filled refrigerant amount determination mode by the input of a refrigerant
amount determination start command, which instructs execution of the filled refrigerant
amount determination, by a user via the remote controller 40. As a result, the control
mode is switched to the filled refrigerant amount determination mode at a timing desired
by the user.
[0097] When the filled refrigerant amount determination completion flag 515 has been raised
and the filled refrigerant amount shortage discrimination flag 516 has been raised
in the filled refrigerant amount determination mode, the mode control unit 53 switches
the control mode to the refrigerant leakage determination mode. Subsequently, the
mode control unit 53 clears the filled refrigerant amount determination completion
flag 515 and the filled refrigerant amount shortage discrimination flag 516.
[0098] On the other hand, when the filled refrigerant amount shortage discrimination flag
516 is not raised in the state of the filled refrigerant amount determination completion
flag 515 having been raised in the filled refrigerant amount determination mode, the
mode control unit 53 switches the control mode to the normal operation mode. Subsequently,
the mode control unit 53 clears the filled refrigerant amount determination completion
flag 515.
(4-4) Actuator control unit 54
[0099] The actuator control unit 54 controls, in accordance with the control program, the
operation of the actuators (for example, the compressor 11, the heat source-side expansion
valve 15, the injection valve 16, the utilization-side expansion valve 32 and the
like) included in the refrigeration apparatus 100 (the heat source unit 10 and the
utilization unit 30) depending on the situation. The actuator control unit 54 discriminates
the control mode that has been changed to by referring to the control mode discrimination
flag 513, and controls the operation of each actuator on the basis of the control
mode that has been changed to.
[0100] For example, in the normal operation mode, the actuator control unit 54 controls
in real time the operating capacity of the compressor 11, the rotation frequency of
the heat source-side fan 20 and the utilization-side fan 36, and the opening degree
of the heat source-side expansion valve 15 and the injection valve 16 so that the
cooling operation is performed in accordance with the set temperature and the detection
values of the various sensors.
[0101] The actuator control unit 54 also controls the operation of each actuator so that
the refrigerant collection operation is performed during the filled refrigerant amount
determination mode. The refrigerant collection operation is an operation of collecting
a portion of the refrigerant in the refrigerant circuit RC to the heat source unit
10 (especially the receiver 13). Specifically, during the refrigerant collection operation,
the actuator control unit 54 sets the heat source-side expansion valve 15 and the
injection valve 16 to a closed state that blocks flow of the refrigerant, and causes
the compressor 11 to operate at the rotational frequency for the refrigerant collection
operation. Thereby, a portion of the refrigerant in the refrigerant circuit RC is
collected to the heat source unit 10. In the present embodiment, the rotational frequency
of the compressor 11 during the refrigerant collection operation is set to the maximum
rotational frequency so that refrigerant collection may be completed in a shortest
time.
[0102] The actuator control unit 54, after the start of the refrigerant collection operation,
completes the refrigerant collection operation on the occasion of a state having arisen
in which the refrigerant collection is presumed to have been ended (specifically,
the state in which the intake pressure LP is less than a predetermined threshold value
ΔTh). The actuator control unit 54 then stops the compressor 11 and raises the refrigerant
collection completion flag 514. Note that the threshold value ΔTh is set to a value
that does not go below atmospheric pressure on the basis of the refrigerant amount
enclosed in the refrigerant circuit RC and the refrigerant circulation amount determined
from the characteristics of the compressor 11. In the present embodiment, the threshold
value ΔTh is set to 0.3 MPa.
(4-5) Filled refrigerant amount shortage discriminating unit 55
[0103] When the refrigerant collection completion flag 514 is raised during the filled refrigerant
amount determination mode (that is, when the refrigerant collection operation is completed),
the filled refrigerant amount shortage discriminating unit 55 performs determination
of the filled refrigerant amount that determines whether or not the refrigerant amount
filled in the refrigerant circuit RC is suitable. Specifically, the filled refrigerant
amount shortage discriminating unit 55, in the filled refrigerant amount determination,
refers to the detection value of the liquid level detection sensor 25 stored in the
storage unit 51 (liquid level height Lh) and determines whether the liquid level height
Lh is less than the predetermined reference value Sh.
[0104] When the liquid level height Lh is equal to or greater than the reference value Sh,
the filled refrigerant amount shortage discriminating unit 55 raises the filled refrigerant
amount determination completion flag 515 indicating that determination of the suitability
of the filled refrigerant amount is completed. On the other hand, when the liquid
level height Lh is less than the reference value Sh, the filled refrigerant amount
shortage discriminating unit 55 raises the filled refrigerant amount determination
completion flag 515 and also raises the filled refrigerant amount shortage discrimination
flag 516 indicating that the refrigerant amount filled in the refrigerant circuit
RC is insufficient
(4-6) Display control unit 56
[0105] The display control unit 56 is a function part that controls operation of the remote
controller 40 as a display device. The display control unit 56 causes the remote controller
40 to output predetermined information for displaying information concerning the operational
state or situation to the user. For example, the display control unit 56 causes the
remote controller 40 to display various information such as a set temperature during
the cooling operation in the normal mode.
[0106] The display control unit 56 causes the remote controller 40 to display various information
indicating that the refrigerant collection operation is being performed during the
refrigerant collection operation in the filled refrigerant amount determination mode.
[0107] The display control unit 56 displays information urging the user a predetermined
action during the refrigerant leakage determination mode.
[0108] For example, the display control unit 56 causes the remote controller 40 to display
text information requesting the user to switch the liquid-side closing valve 17 and
the gas-side closing valve 18 to the closed state (closing valve close switching request
information) when a bit in the control mode discrimination flag 513 identifying a
switch to the refrigerant leakage determination mode has been raised (that is, when
changed to the refrigerant leakage determination mode).
[0109] The display control unit 56 also causes the remote controller 40 to display text
information requesting the user to switch the gas-side closing valve 18 to the open
state (gas-side closing valve open switching request information) when a bit in the
identifying process progress flag 517 indicating that a first identifying process
(described below) is completed has been raised and a bit in the refrigerant leakage
spot discrimination flag 518 identifying that a refrigerant leakage has occurred in
the first flow path RP1 has not been raised (that is, when it is assumed that the
first identifying process has ended and that a refrigerant leakage has not occurred
in the first flow path RP1) during the refrigerant leakage determination mode.
[0110] The display control unit 56 also causes the remote controller 40 to display text
information requesting the user to switch the liquid-side closing valve 17 to the
open state (liquid-side closing valve open switching request information) when a bit
in the identifying process progress flag 517 indicating that a third identifying process
(described below) is completed has been raised and a bit in the refrigerant leakage
spot discrimination flag 518 identifying that a refrigerant leakage has occurred in
the third flow path RP3 has not been raised (that is, when it is assumed that the
third identifying process has ended and that a refrigerant leakage has not occurred
in the third flow path RP3) during the refrigerant leakage determination mode.
[0111] The display control unit 56, when any bit of the refrigerant leakage spot discrimination
flag 518 has been raised, also causes the remote controller 40 to display information
for reporting that a refrigerant leakage has occurred in accordance with the spot
corresponding to the raised bit (refrigerant leakage spot reporting information) and
information requesting that a serviceman be notified.
[0112] The controller 50 also causes the remote controller 40 to display information reporting
that the filled refrigerant amount in the refrigerant circuit RC is not suitable (insufficient)
(filled refrigerant amount shortage reporting information) when any bit of the refrigerant
leakage spot discrimination flag 518 has not been raised in the case of the identifying
process progress flag 517 having indicated that the third identifying process is completed
(that is, when a refrigerant leakage spot is not identified in the case of the refrigerant
leakage spot identifying process being completed).
(4-7) Refrigerant leakage spot identifying unit 57
[0113] The refrigerant leakage spot identifying unit 57 executes a refrigerant leakage spot
identifying process when a bit is raised in the control mode discrimination flag 513
identifying a switch to the refrigerant leakage determination mode (that is, a transition
to the refrigerant leakage determination mode).
[0114] The first identifying process, a second identifying process, and the third identifying
process are mainly included in the refrigerant leakage spot identifying process. The
first identifying process is a process for discriminating whether or not there is
a leakage of the refrigerant in the first flow path RP1 (refer to FIG. 2). The second
identifying process is a process for discriminating whether or not there is a leakage
of the refrigerant in the second flow path RP2 (refer to FIG. 2). The third identifying
process is a process for discriminating whether or not there is a leakage of the refrigerant
in the third flow path RP3 (refer to FIG. 2).
[0115] Specifically, the refrigerant leakage spot identifying unit 57 refers to the command
discrimination flag 519 during the refrigerant leakage determination mode, and upon
discriminating that a closing valve close notification command has been received,
executes the first identifying process. Here, the situation of the closing valve close
notification command being received is a situation presumed as the liquid-side closing
valve 17 and the gas-side closing valve 18 having been switched to the closed state
by the user, and a situation presumed as the first flow path RP1, the second flow
path RP2 and the third flow path RP3 each being in a divided state.
[0116] In the first identifying process, the refrigerant leakage spot identifying unit 57
determines whether or not there is a leakage of the refrigerant in the first flow
path RP1 by referring to the detection value of the intake pressure sensor 21 (intake
pressure LP) and also referring to the detection value of the discharge pressure sensor
22 (discharge pressure HP). More specifically, in the first identifying process, the
refrigerant leakage spot identifying unit 57 determines whether there is a leakage
of the refrigerant in the second heat source-side gas refrigerant pipe P3 (low-pressure
side) by referring to the detection value of the intake pressure sensor 21 (intake
pressure LP) and determining whether or not a fluctuation in the intake pressure LP
by a percentage exceeding a predetermined threshold is continuous. The refrigerant
leakage spot identifying unit 57 determines whether or not there is a leakage of the
refrigerant in the first heat source-side gas refrigerant pipe P1 and the heat source-side
liquid refrigerant pipe P2 (high-pressure side) by referring to the detection value
of the discharge pressure sensor 22 (discharge pressure HP) and determining whether
or not a fluctuation in the discharge pressure HP by a percentage exceeding a predetermined
threshold is continuous.
[0117] The refrigerant leakage spot identifying unit 57, upon determining that a refrigerant
leakage has occurred in the first flow path RP1 as a result of the first identifying
process, raises a bit corresponding to the first flow path RP1 in the refrigerant
leakage spot discrimination flag 518 so as to indicate that information. In that event,
the refrigerant leakage spot identifying unit 57 raises the bit corresponding to the
low-pressure side of the first flow path RP1 when a refrigerant leakage has occurred
on the low-pressure side of the first flow path RP1, and raises the bit corresponding
to the high-pressure side of the first flow path RP1 when a refrigerant leakage has
occurred on the high-pressure side.
[0118] The refrigerant leakage spot identifying unit 57, upon discriminating the reception
of the gas-side closing valve open notification command, executes the second identifying
process. Here, the situation of the gas-side closing valve open notification command
being received is a situation presumed as the gas-side closing valve 18 having been
switched to the open state by the user, and a situation presumed as the inlet side
of the first flow path RP1 and the outlet side of the second flow path RP2 being in
a state of communication with each other, and the inlet side of the second flow path
RP2 and the outlet side of the third flow path RP3 being in the divided state. The
refrigerant leakage spot identifying unit 57, in the second identifying process, determines
whether or not there is a leakage of the refrigerant in the second flow path RP2 by
referring to the detection value of the intake pressure sensor 21 (intake pressure
LP) and determining whether or not a fluctuation in the intake pressure LP by a percentage
exceeding a predetermined threshold is continuous. The refrigerant leakage spot identifying
unit 57, upon determining that a refrigerant leakage has occurred in the second flow
path RP2 based on the result of the second identifying process, raises the bit corresponding
to the second flow path RP2 in the refrigerant leakage spot discrimination flag 518
so as to indicate that information.
[0119] The refrigerant leakage spot identifying unit 57, in the event of having determined
that a refrigerant leakage has not occurred in the second flow path RP2 upon completion
of the second identifying process, after setting the utilization-side expansion valve
32 to a predetermined opening degree to switch the utilization-side expansion valve
32 from the closed state to the open state, executes the third identifying process.
Here, the situation of the utilization-side expansion valve 32 being switched to the
open state after completion of the second identifying process is a situation presumed
as the state of the inlet side of the second flow path RP2 (in greater detail, the
first flow path RP1) and the outlet side of the third flow path RP3 being in communication
with each other, and the outlet side of the first flow path RP1 and the inlet side
of the third flow path RP3 being divided. In the third identifying process, the refrigerant
leakage spot identifying unit 57 determines whether or not there is a leakage of the
refrigerant in the third flow path RP3 by referring to the detection value of the
intake pressure sensor 21 (intake pressure LP) and determining whether or not a fluctuation
in the intake pressure LP by a percentage exceeding a predetermined threshold is continuous.
The refrigerant leakage spot identifying unit 57, upon determining that a refrigerant
leakage has occurred in the third flow path RP3 based on the result of the third identifying
process, raises the bit corresponding to the third flow path RP3 in the refrigerant
leakage spot discrimination flag 518 so as to indicate that information.
[0120] The threshold values used in the first identifying process, the second identifying
process, and the third identifying process are suitably set in accordance with the
design specifications and installation environment. For example, the refrigerant leakage
spot identifying unit 57 sets the threshold values based on the pressure reference
value table stored in the pressure reference value storage region 512. In the control
program, the threshold values may be set beforehand.
[0121] In the refrigerant leakage spot identifying processes performed in the above manner,
the determination of whether or not there is leakage of the refrigerant in the second
flow path RP2 and the third flow path RP3 is performed on the basis of the detection
value of the intake pressure sensor 21 (refrigerant state detection sensor) disposed
in the first flow path RP1. That is, it is possible to individually determine whether
or not there is a leakage of the refrigerant in each refrigerant flow path even without
disposing a refrigerant state detection sensor such as a pressure sensor or temperature
sensor in each refrigerant flow path.
(5) Processing flow of controller 50
[0122] An example of the processing flow of the controller 50 will be described below while
referring to FIG. 4 and FIG. 5. FIG. 4 and FIG. 5 are flowcharts that show an example
of the processing flow of the controller 50.
[0123] When power is turned on, the controller 50 performs processing by the flow shown
from Steps S101 to S125 in FIG. 4 and FIG. 5. In FIG. 4 and FIG. 5, processing in
the case of transition to the normal operation mode is shown from Steps S102 to S104,
processing in the case of transition to the filled refrigerant amount determination
mode is shown from Steps S105 to S110, and processing in the case of transition to
the refrigerant leakage determination mode is shown from Steps S111 to S125. In greater
detail, it is shown that the cooling operation is performed in Step S104, the refrigerant
collection operation is performed in Steps S106 and S107, the filled refrigerant amount
determination is performed in Steps S109 and S110, and the refrigerant leakage spot
identifying process is performed from Steps S111 to S124.
[0124] Note that the processing flows shown in FIG. 4 and FIG. 5 are merely exemplary and
may be suitably modified. For example, the order of the steps may be changed within
a scope in which contradictions do not arise, and some steps may be executed in parallel
with other steps.
[0125] In Step S101, the controller 50 advances to Step S105 when a refrigerant amount determination
start command has been input. In contrast, when a refrigerant amount determination
start command has not been input, the process advances to Step S102.
[0126] In Step S102, the controller 50 transitions to the normal operation mode. Thereafter,
the process advances to Step S103.
[0127] In Step S103, the controller 50 returns to Step S101 when an operation command (operation
start instruction) has not been input. In contrast, when an operation command has
been input, the process advances to Step S104.
[0128] In Step S104, the controller 50 performs the cooling operation by controlling in
real time the state of each actuator in accordance with the set temperature that has
been set and the detection values of the various sensors (20 to 25). Also, the controller
50 causes various information such as the set temperature to be displayed in the remote
controller 40. Thereafter, the process returns to Step S101.
[0129] In Step S105, the controller 50 transitions to the filled refrigerant amount determination
mode. Thereafter, the process advances to Step S106.
[0130] In Step S106, the controller 50 starts the refrigerant collection operation, which
collects the refrigerant in the refrigerant circuit RC in the receiver 13, by performing
control to put the heat source-side expansion valve 15 and the injection valve 16
into a closed state, and causing the compressor 11 to operate at a predetermined rotational
frequency (here, the maximum rotational frequency). Then, the process advances to
Step S107.
[0131] In Step S107, the controller 50 determines whether or not the intake pressure LP
is less than the threshold value ΔTh. As a result of the determination, when the intake
pressure LP is equal to or greater than the threshold value ΔTh, the determination
is repeated in Step S107. On the other hand, when the intake pressure LP is less than
the threshold value ΔTh, the process advances to Step S108.
[0132] In Step S108, in response to the situation having arisen in which it is presumed
that the intake pressure LP is less than the threshold value ΔTh, and the refrigerant
collection to the receiver 13 is completed, the controller 50 stops the compressor
11 to complete the refrigerant collection operation. Then, the process advances to
Step S109.
[0133] In Step S109, the controller 50 starts the filled refrigerant amount determination
that determines whether or not the refrigerant amount filled in the refrigerant circuit
RC is suitable, and whether or not a refrigerant leakage has occurred in the refrigerant
circuit RC. Then the process advances to Step S110.
[0134] In Step S110, the controller 50 determines whether or not the liquid level height
Lh is equal to or greater than the reference value Sh. As a result of the determination,
when the liquid level height Lh is equal to or greater than the reference value Sh,
the process returns to Step S102. On the other hand, when the liquid level height
Lh is less than the reference value Sh, the process advances to Step Sill.
[0135] In Step Sill, the controller 50 transitions to the refrigerant leakage determination
mode. Then, the process advances to Step S112.
[0136] In Step S112, the controller 50 switches the utilization-side expansion valve 32
to the closed state. Also, the controller 50 causes the remote controller 40 to display
closing valve close switching request information requesting the user to switch (information
that requests switching of the closing valve, so that the user is requested) the liquid-side
closing valve 17 and the gas-side closing valve 18 to the closed state. Then, the
process advances to Step S113.
[0137] In Step S113, when the closing valve close notification command has not been input
to the remote controller 40 by the user (that is, when it is presumed that the switch
to the closed state of the liquid-side closing valve 17 and the gas-side closing valve
18 has not been performed), the controller 50 advances to Step S125. On the other
hand, when the closing valve close notification command has been input to the remote
controller 40 by the user (that is, when it is presumed that the switch to the closed
state of the liquid-side closing valve 17 and the gas-side closing valve 18 is completed),
the controller 50 advances to Step S114.
[0138] In Step S114, the controller 50 starts the first identifying process in the refrigerant
leakage spot identifying process. Specifically, the controller 50 determines whether
or not there is a leakage of the refrigerant in the first flow path RP1 by determining
whether or not the intake pressure LP is fluctuating by a percentage exceeding a predetermined
threshold value, and whether or not the discharge pressure HP is fluctuating by a
percentage exceeding a predetermined threshold value. Then, the controller 50 advances
to Step S115.
[0139] In Step S115, when as a result of the first identifying process a refrigerant leakage
is presumed to have occurred in the first flow path RP1 (that is, when the intake
pressure LP or the discharge pressure HP is fluctuating by a percentage exceeding
the predetermined threshold value), the controller 50 advances to Step S124. On the
other hand, when as a result of the first identifying process a refrigerant leakage
is presumed to have not occurred in the first flow path RP1 (that is, when the intake
pressure LP or the discharge pressure HP is not fluctuating by a percentage exceeding
the predetermined threshold value), the controller 50 advances to Step S116.
[0140] In Step S116, the controller 50 causes the remote controller 40 to display gas-side
closing valve open switching request information requesting the user to switch the
gas-side closing valve 18 to the open state. Then, the controller 50 advances to Step
S117.
[0141] In Step S117, when the gas-side closing valve open notification command has not been
input to the remote controller 40 by the user (that is, when it is presumed that the
switch to the open state of the gas-side closing valve 18 has not been performed),
the controller 50 advances to Step S125. On the other hand, when the gas-side closing
valve open notification command has been input to the remote controller 40 by the
user (that is, when it is presumed that the switch to the open state of the gas-side
closing valve 18 is completed), the controller advances to Step S118.
[0142] In Step S118, the controller 50 starts the second identifying process in the refrigerant
leakage spot identifying process. Specifically, the controller 50 determines whether
or not there is a leakage of the refrigerant in the second flow path RP2 by determining
whether or not the intake pressure LP is fluctuating by a percentage exceeding a predetermined
threshold value. Then, the controller 50 advances to Step S119.
[0143] In Step S119, when as a result of the second identifying process a refrigerant leakage
is presumed to have occurred in the second flow path RP2 (that is, when the intake
pressure LP is fluctuating by a percentage exceeding the predetermined threshold value),
the controller 50 advances to Step S124. On the other hand, when as a result of the
second identifying process a refrigerant leakage is presumed to have not occurred
in the second flow path RP2 (that is, when the intake pressure LP is not fluctuating
by a percentage exceeding the predetermined threshold value), the controller 50 advances
to Step S120.
[0144] In Step S120, the controller 50 sets the utilization-side expansion valve 32 to a
predetermined opening degree to switch the utilization-side expansion valve 32 from
the closed state to the open state. Then the controller 50 advances to Step S121.
[0145] In Step S121, the controller starts the third identifying process in the refrigerant
leakage spot identifying process. Specifically, the controller 50 determines whether
or not there is a leakage of the refrigerant in the third flow path RP3 by determining
whether or not the intake pressure LP is fluctuating by a percentage exceeding a predetermined
threshold value. Then, the controller 50 advances to Step S122.
[0146] In Step S122, when as a result of the third identifying process a refrigerant leakage
is presumed to have occurred in the third flow path RP3 (that is, when the intake
pressure LP is fluctuating by a percentage exceeding the predetermined threshold value),
the controller 50 advances to Step S124. On the other hand, when as a result of the
third identifying process a refrigerant leakage is presumed to have not occurred in
the third flow path RP3 (that is, when the intake pressure LP is not fluctuating by
a percentage exceeding the predetermined threshold value), the controller 50 advances
to Step S123.
[0147] In Step S123, in response to a refrigerant leakage spot not being identified as a
result of the refrigerant leakage spot identifying process, the controller 50 causes
filled refrigerant amount shortage reporting information reporting that the filled
refrigerant amount in the refrigerant circuit RC is not suitable (insufficient) to
be displayed in the remote controller 40 and then stands by.
[0148] In Step S124, in response to a refrigerant leakage spot being identified as a result
of the refrigerant leakage spot identifying process, the controller 50 causes the
refrigerant leakage spot reporting information reporting the spot where the refrigerant
leakage has occurred to be displayed in the remote controller 40 and then stands by.
[0149] In Step S125, in response to the presumption that the closing valve close notification
command has not been input to the remote controller 40 by the user in spite of closing
valve close switching request information is displayed (that is, switching of the
liquid-side closing valve 17 and the gas-side closing valve 18 to the closed state
not being performed), or that the gas-side closing valve open notification command
has not been input to the remote controller 40 by the user in spite of gas-side closing
valve open switching request information is displayed (that is, switching of the gas-side
closing valve 18 to the open state not being performed), the controller 50 causes
error information to be displayed in the remote controller 40 reporting that the refrigerant
leakage spot identifying process cannot be executed and then stands by.
(6) The operation state of each unit of the refrigeration apparatus 100
[0150] Here, the operation of each unit of the refrigeration apparatus 100 in the filled
refrigerant amount determination mode and the refrigerant leakage determination mode
is described. FIG. 6 is a sequence diagram that schematically shows the operation
of each unit of the refrigeration apparatus 100 in the filled refrigerant amount determination
mode. FIG. 7 is a sequence diagram that schematically shows the operation of each
unit of the refrigeration apparatus 100 in the refrigerant leakage determination mode.
FIG. 6 and FIG. 7 show that the filled refrigerant amount determination is performed
in period S1, the first identifying process is performed in period S2, the second
identifying process is performed in period S3, and the third identifying process is
performed in period S4.
(6-1) Period S1
[0151] In period S1, the control mode of the controller 50 transitions to the filled refrigerant
amount determination mode on the occasion of the refrigerant amount determination
start command being input to the remote controller 40.
[0152] As a process related to the filled refrigerant amount determination mode, the controller
50 outputs a drive signal to heat source-side expansion valve 15 (and the injection
valve 16) to switch the heat source-side expansion valve 15 (and the injection valve
16) to the closed state. In response, the heat source-side expansion valve 15 (and
the injection valve 16) is switched to the closed state.
[0153] The controller 50 outputs a drive signal to the compressor 11 to cause the compressor
11 to be driven at a predetermined rotational frequency (maximum rotational frequency).
In response, the compressor 11 is driven at the maximum rotational frequency.
[0154] Next, the controller 50 sends an instruction to the remote controller 40 to cause
the remote controller 40 to display that the filled refrigerant amount determination
operation is underway. In response, the remote controller 40 displays that the filled
refrigerant amount determination operation is underway.
[0155] Then, the controller 50, in response to the intake pressure LP being less than the
threshold value ΔTh, determines that the refrigerant collection is completed and outputs
a stop signal to the compressor 11 in order to stop the compressor 11. In response,
the compressor 11 stops driving.
[0156] The controller 50 executes the filled refrigerant amount determination, and as a
result of the determination, determines that the filled refrigerant amount is insufficient.
As a result, the controller 50 transitions to the refrigerant leakage determination
mode.
(6-2) Period S2
[0157] In period S2, the controller 50, after transition to the refrigerant leakage determination
mode, outputs a drive signal to the utilization-side expansion valve 32 to switch
the utilization-side expansion valve 32 to the closed state. In response, the utilization-side
expansion valve 32 is switched to the closed state.
[0158] The controller 50 also sends an instruction to the remote controller 40 to display
closing valve close switching request information for dividing the first flow path
RP1, the second flow path RP2, and the third flow path RP3. In response, the remote
controller 40 displays the closing valve close switching request information.
[0159] After the closing valve close switching request information is displayed, the user
switches the liquid-side closing valve 17 and the gas-side closing valve 18 to the
closed state, and inputs the closing valve close notification command to the remote
controller 40.
[0160] Subsequently, the controller 50 executes the first identifying process for discriminating
whether or not there is a leakage of the refrigerant in the first flow path RP1.
[0161] In this way, in period S2, after a step (first step) is performed in which the refrigerant
circuit RC is divided into the plurality of refrigerant flow paths by setting each
of the valves (32, 17 and 18) to the closed state in the state of the compressor 11
being stopped, a step (second step) is performed for determining whether or not there
is a leakage of the refrigerant by detecting a change in the state of the refrigerant
in the first flow path RP1.
(6-3) Period S3
[0162] In period S3, following the completion of the first identifying process, the controller
50, in response to a result that a refrigerant leakage spot has not been identified,
sends an instruction to the controller 40 to display gas-side closing valve open switching
request information for putting the inlet side (gas side) of the first flow path RP1
and the outlet side of the second flow path RP2 into communication. In response, the
remote controller 40 displays gas-side closing valve open switching request information.
[0163] After the gas-side closing valve open switching request information is displayed,
the user switches the gas-side closing valve 18 to the open state, and inputs the
gas-side closing valve open notification command to the remote controller 40.
[0164] Subsequently, the controller 50 executes the second identifying process for discriminating
whether or not there is a leakage of refrigerant in the second flow path RP2.
[0165] In this way, in period S3, a change in the state of the refrigerant in the second
flow path RP2 is detected by switching the gas-side closing valve 18, which divides
the first flow path RP1 with the intake pressure sensor 21 (refrigerant state detection
sensor) being disposed and the second flow path RP2 without the intake pressure sensor
21, to the open state, and detecting a change in the intake pressure LP by the intake
pressure sensor 21 in the state of the first flow path RP1 and the second flow path
RP2 being put in communication with each other.
(6-4) Period S4
[0166] In period S4, following the completion of the second identifying process, the controller
50, in response to a result that a refrigerant leakage spot has not been identified,
in order to set the utilization-side expansion valve 32 to a predetermined opening
degree to switch the utilization-side expansion valve 32 to an open state and put
the inlet side (gas side) of the first flow path RP1 and the outlet side of the third
flow path RP3 into communication. In response, the utilization-side expansion valve
32 is switched to the open state.
[0167] Next, the controller 50 executes the third identifying process for discriminating
whether or not there is a leakage of the refrigerant in the third flow path RP3.
[0168] In this way, in period S4, a change in the state of the refrigerant in the third
flow path RP3 is detected by switching the utilization-side expansion valve 32, which
divides the first flow path RP1 with the intake pressure sensor 21 (refrigerant state
detection sensor) from the third flow path RP3 without the intake pressure sensor
21, to the open state, and detecting a change in the intake pressure LP by the intake
pressure sensor 21 in the state of the first flow path RP1 and the third flow path
RP3 being put in communication with each other.
[0169] Subsequently, in accordance with the result of the third identifying process (refrigerant
leakage spot identifying process), the controller 50 sends an instruction to the remote
controller 40 to display predetermined information (refrigerant leakage spot reporting
information or filled refrigerant amount shortage reporting information). In response,
the remote controller 40 displays the instructed information.
(7) Characteristics of the refrigeration apparatus 100
(7-1)
[0170] According to the method of identifying a refrigerant leakage spot of the embodiment,
it is possible to provide a method of identifying a refrigerant leakage spot that
is capable of identifying a refrigerant leakage spot when a refrigerant leakage has
occurred in a refrigerant circuit RC while restraining an increase in cost.
[0171] That is, in an apparatus that has a refrigerant circuit, when a refrigerant leakage
occurs for reasons such as damage to the pipe and degradation of components, it is
necessary to quickly detect that a refrigerant leakage has occurred from the standpoint
of ensuring the safety of humans. Depending on the installation environment of the
apparatus, when a refrigerant leakage has occurred, since minimizing the number of
repair steps, a quick restoration, and clarification of the cause and the spot of
responsibility become necessary, it is necessary to quickly identify not only the
fact that a refrigerant leakage has occurred but also the spot where the refrigerant
leakage has occurred.
[0172] However, while it is possible to determine the fact that a refrigerant leakage has
occurred according to previously proposed methods, it is not possible to concretely
identify the spot where a refrigerant leakage has occurred. In addition, while it
is possible to identify not only that a refrigerant leakage has occurred but also
the spot where the refrigerant leakage has occurred, since installation of a plurality
of refrigerant leakage sensors is required, increasing cost becomes a concern.
[0173] On this point, the method of identifying a refrigerant leakage spot of the aforedescribed
embodiment includes: a step (first step) in which the refrigerant circuit RC is divided
into the plurality of refrigerant flow paths by each of the valves (the liquid-side
closing valve 17, the gas-side closing valve 18, and the utilization-side expansion
valve 32) being set to the closed state in the state of the compressor 11 being stopped;
and a step (second step) for determining whether or not there is leakage of the refrigerant
in each refrigerant flow path (RP1, RP2, RP3) by detecting a change in the pressure
of the refrigerant in each refrigerant flow path.
[0174] Thereby, the refrigerant circuit RC is divided into the plurality of refrigerant
flow paths (RP1, RP2, RP3), and whether or not there is a leakage of the refrigerant
in each refrigerant flow path is determined. As a result, a refrigerant leakage spot
can be identified without installing a plurality of refrigerant leakage sensors. Therefore,
it is possible to identify a refrigerant leakage spot when a refrigerant leakage has
occurred while restraining an increase in cost.
(7-2)
[0175] The method of identifying a refrigerant leakage spot of the aforedescribed embodiment
identifies whether or not there is a leakage of the refrigerant in each refrigerant
flow path by detecting a change in the pressure of the refrigerant in each refrigerant
flow path (RP1, RP2, RP3). In the steps, the pressure of the refrigerant in the first
flow path RP1 in which a pressure sensor (intake pressure sensor 21 or discharge pressure
sensor 22) is disposed is detected by the pressure sensor. Then, the gas-side closing
valve 18 that divides the first flow path RP1 and the second flow path RP2, or the
utilization-side expansion valve 32 that divides the first flow path RP1 from the
third flow path RP3 is switched from the closed state to the open state by the user.
In the state of the first flow path RP1 and the second flow path RP2 or the third
flow path RP3 being in communication with each other, a change in the pressure of
the refrigerant in the second flow path RP2 or the third flow path RP3 in which a
pressure sensor is not disposed is detected by the intake pressure sensor 21 disposed
in the first flow path RP1.
[0176] Thereby, it becomes possible to detect the state of the refrigerant in the second
flow path RP2 and the third flow path RP3 in which a refrigerant state detection sensor
such as a pressure sensor or a temperature sensor is not disposed. As a result, a
refrigerant leakage spot in the refrigerant circuit RC can be identified without disposing
a refrigerant state detection sensor in each refrigerant flow path. Therefore, it
is possible to identify a refrigerant leakage spot when a refrigerant leakage has
occurred while restraining an increase in cost.
(7-3)
[0177] A method of identifying a refrigerant leakage spot of the aforedescribed embodiment
includes a step for collecting a portion of the refrigerant in the refrigerant circuit
RC in a receiver 13 that is capable of storing the refrigerant, and after the completion
of the step that collects the refrigerant, the refrigerant circuit RC is divided into
a plurality of refrigerant flow paths by switching each of the valves (the liquid-side
closing valve 17, the gas-side closing valve 18, and the utilization-side expansion
valve 32) to a closed state after the compressor 11 is stopped. Thereby, it becomes
possible to detect a change in the state of the gas refrigerant that exists in each
refrigerant flow path (RP1, RP2, and RP3) after collecting the liquid refrigerant
in the receiver 13. That is, in the step for determining whether or not there is a
leakage of the refrigerant in each refrigerant flow path by detecting a change in
the pressure of the refrigerant, it becomes possible to detect a change in the pressure
of a gas refrigerant, in which the change in pressure when a refrigerant leakage has
occurred is more noticeable (earlier) than a liquid refrigerant. Therefore, it is
possible to perform the determination with high precision, and it is possible to perform
the determination in a shorter time compared to the case of performing the determination
by detecting a change in pressure of a liquid refrigerant.
(7-4)
[0178] In the method of identifying a refrigerant leakage spot of the aforedescribed embodiment,
on the occasion of the filled refrigerant amount being determined to be unsuitable
in the filled refrigerant amount determination operation, a step is performed that
stops the compressor 11 and switches each of the valves (the liquid-side closing valve
17, the gas-side closing valve 18, and the utilization-side expansion valve 32) to
a closed state to divide the refrigerant circuit RC into a plurality of refrigerant
flow paths.
[0179] Thereby, after it is determined that the filled refrigerant amount in the refrigerant
circuit RC is insufficient, a step for stopping the compressor 11 and dividing the
refrigerant circuit RC into a plurality of refrigerant flow paths and a step for determining
whether or not there is a leakage of the refrigerant in any of the refrigerant flow
paths (that is, a step for determining a refrigerant leakage spot) are performed.
That is, a configuration that does not require the compressor 11 to be stopped each
time to determine whether or not there is a leakage of the refrigerant decreases degradation
of components that are subject to temperature control and restrains a decrease in
comfort.
(7-5)
[0180] The method of identifying a refrigerant leakage spot of the aforedescribed embodiment
includes a step for outputting to the remote controller 40 refrigerant leakage spot
reporting information that reports the refrigerant flow path (RP1, RP2, and RP3) where
it was determined that a leakage of the refrigerant has occurred.
[0181] Thereby, when a leakage of the refrigerant has occurred, the refrigerant leakage
spot reporting information that identifies the spot where a leakage of the refrigerant
has occurred is displayed in the remote controller 40. As a result, when a leakage
of the refrigerant has occurred, it becomes easy for the user to recognize the fact
that a leakage of the refrigerant has occurred and the spot where the leakage of the
refrigerant has occurred, and the user is prompted to take action. Thereby, safety
with regard to refrigerant leakages is enhanced.
(8) Modifications
[0182] The aforedescribed embodiment can be suitably modified as indicated by the following
modifications. The modifications may be combined with or applied to other modifications
within a scope in which contradictions do not arise.
(8-1) Modification A
[0183] In the aforedescribed embodiment, the manual gas-side closing valve 18 is used as
a valve for dividing the inlet side (gas side) of the first flow path RP1 from the
outlet side of the second flow path RP2, and the manual liquid-side closing valve
17 is used as a valve for dividing the outlet side (liquid side) of the first flow
path RP 1 and the inlet side of the third flow path RP3.
[0184] However, a solenoid valve that is switchable to an open state or a closed state by
being energized, or a motor-operated valve whose opening degree (including closed
state) is switchable by the supply of a predetermined drive voltage may be used as
the liquid-side closing valve 17 and/or the gas-side closing valve 18.
[0185] In this case, in the process according to the refrigerant leakage determination mode
the need is eliminated to switch the liquid-side closing valve 17 or the gas-side
closing valve 18 to the closed state or open state by the user, and the need is eliminated
to display the closing valve open switching request information or the gas-side closing
valve open switching request information in the remote controller 40. Therefore, Step
S112 of FIG. 5 may be configured so as to switch the liquid-side closing valve 17
and the gas-side closing valve 18 constituted by a motor-operated valve or a solenoid
valve to the closed state by supplying or blocking a predetermined drive voltage to
the liquid-side closing valve 17 and the gas-side closing valve 18, instead of causing
closing valve close switching request information to be displayed in the remote controller
40. Also, Step S116 of FIG. 5 may be configured so as to switch the gas-side closing
valve 18 to the open state by supplying or blocking a predetermined drive voltage
to the gas-side closing valve 18 constituted by a motor-operated valve or a solenoid
valve, instead of causing gas-side closing valve open switching request information
to be displayed in the remote controller 40.
[0186] As a result, it is possible to execute the step for identifying a refrigerant leakage
spot without manual intervention. That is, the method of identifying a refrigerant
leakage spot of the embodiment is automatically executed. In this case, the refrigeration
apparatus 100 functions as a refrigerant leakage spot identifying apparatus that is
capable of automatically identifying a refrigerant leakage spot.
(8-2) Modification B
[0187] The method of identifying a refrigerant leakage spot of the aforedescribed embodiment
was applied to the refrigeration apparatus 100 that performs cooling of the compartment
of a refrigerating warehouse or a store showcase. However, the present invention,
without being limited thereto, can also be applied to other refrigeration apparatuses.
For example, the present invention may also be applied to an air conditioning system
(air-conditioner) that achieves air conditioning by performing cooling and other in
a building. The present invention can also be applied to for example a refrigeration
apparatus that is constituted so as to have the utilization-side heat exchanger 33
function as a radiator or condenser of refrigerant by disposing a four-way switching
valve or rearranging the refrigerant pipe in the refrigerant circuit RC in FIG. 1
so as to perform a heating operation or room heating operation of a space in which
the utilization unit 30 is disposed.
[0188] Alternatively, the method of identifying a refrigerant leakage spot of the present
invention may be applied to a refrigeration apparatus 200 for example as shown in
FIG. 8. The refrigeration apparatus 200 is a refrigeration apparatus that performs
cooling in a transport container (in a compartment). Hereinbelow, the parts of the
refrigeration apparatus 200 differing from the refrigeration apparatus 100 will be
described.
[0189] The refrigeration apparatus 200 has a heat source unit 10a that functions as an outdoor
unit in place of the heat source unit 10, and a utilization unit 30a that functions
has an indoor unit in place of the utilization unit 30. A refrigerant circuit RC1
is constituted in place of the refrigerant circuit RC in the refrigeration apparatus
200.
[0190] The refrigeration apparatus 200 has, in the heat source unit 10a, a third heat source-side
gas refrigerant pipe P8 that branches off from the first heat source-side gas refrigerant
pipe P1 and has a fourth heat source-side gas refrigerant pipe P9 that branches off
from the third heat source-side gas refrigerant pipe P8. The refrigeration apparatus
200 also has a third utilization-side liquid refrigerant pipe P10 in the utilization
unit 30a.
[0191] The liquid-side closing valve 17 and the gas-side closing valve 18 are omitted from
the refrigeration apparatus 200. A first gas-side on/off valve 71 (valve) that connects
one end of the second heat source-side gas refrigerant pipe P3 and one end of the
utilization-side gas refrigerant pipe P7 is disposed in the refrigeration apparatus
200. A second gas-side on/off valve 72 (valve) that connects one end of the third
heat source-side gas refrigerant pipe P8 and one end of the second utilization-side
liquid refrigerant pipe P6 is disposed in the refrigeration apparatus 200. A third
gas-side on/off valve 73 (valve) that connects one end of the fourth heat source-side
gas refrigerant pipe P9 and one end of the third utilization-side liquid refrigerant
pipe P10 is disposed in the refrigeration apparatus 200. The first gas-side on/off
valve 71, the second gas-side on/off valve 72, and the third gas-side on/off valve
73 are solenoid valves that are switched between the open state and the closed state
by being energized.
[0192] A capillary tube 32a is disposed as a low-pressure means in place of the utilization-side
expansion valve 32 of the refrigeration apparatus 200. In addition, the heating pipe
31 is included in the third utilization-side liquid refrigerant pipe P10 of the refrigeration
apparatus 200.
[0193] The refrigerant circuit RC1 that is constituted in the refrigeration apparatus 200
is mainly divided into a first flow path RP1' and a second flow path RP2' as shown
in FIG. 9. FIG. 9 is a diagram that schematically shows the first flow path RP1' and
the second flow path RP2' included in the refrigerant circuit RC1.
[0194] The first flow path RP1' (first refrigerant flow path) is a refrigerant flow path
that is constituted in the heat source unit 10a. Specifically, the first flow path
RP1' is a refrigerant flow path that is constituted by the first heat source-side
gas refrigerant pipe P1, the heat source-side liquid refrigerant pipe P2, the second
heat source-side gas refrigerant pipe P3, the injection pipe P4, the third heat source-side
gas refrigerant pipe P8, and the fourth heat source-side gas refrigerant pipe P9.
[0195] The second flow path RP2' (second refrigerant flow path) is a refrigerant flow path
that is constituted in the utilization unit 30a. Specifically, the second flow path
RP2' is a refrigerant flow path that is constituted by the first utilization-side
liquid refrigerant pipe P5, the second utilization-side liquid refrigerant pipe P6,
the third utilization-side liquid refrigerant pipe P10, and the utilization-side gas
refrigerant pipe P7. That is, the second flow path RP2' is a refrigerant flow path
that includes the heating pipe 31, the capillary tube 32a, and the utilization-side
heat exchanger 33.
[0196] That is, the refrigerant circuit RC1 is divided into the plurality of refrigerant
flow paths (RP1' and RP2') by each of the valves (specifically, the first gas-side
on/off valve 71, the second gas-side on/off valve 72, the third gas-side on/off valve
73, and the heat source-side expansion valve 15) being set to the closed state.
[0197] In the refrigerant leakage determination mode of the refrigeration apparatus 200,
the first gas-side on/off valve 71, the second gas-side on/off valve 72, and the third
gas-side on/off valve 73 can be set to the closed state by switching the energized
states thereof, instead of causing the remote controller 40 to display closing valve
open switching request information or gas-side closing valve open switching request
information or the like. The first gas-side on/off valve 71 can be set to the open
state by switching the energized state thereof instead of causing the remote controller
40 to display gas-side closing valve open switching request information.
[0198] By performing this processing in the refrigerant leakage determination mode, it is
possible to apply the method of identifying a refrigerant leakage spot according to
an embodiment of the present invention also to the refrigeration apparatus 200, thereby
exhibiting the same effect as the aforedescribed embodiment.
(8-3) Modification C
[0199] In the aforedescribed embodiment, the refrigerant collection operation was configured
to be completed when the refrigerant collection is treated as completed by the detection
value (intake pressure LP) of the intake pressure sensor 21 being less than the predetermined
threshold value ΔTh (refer to Step S107 and Step S108 in FIG. 4). However, the trigger
for completion of the refrigeration collection operation may be suitably changed in
accordance with the design specifications and installation environment.
[0200] For example, the refrigerant collection operation may be configured to be completed
when the refrigerant collection is treated as completed by the detection value of
the discharge pressure sensor 22 (discharge pressure HP) being less than a predetermined
value.
[0201] For example the refrigerant collection operation may also be configured to be completed
on the occasion of the passage of a preset predetermined time after the start of the
refrigerant collection operation.
[0202] In the aforedescribed embodiment, the threshold value ΔTh was set to 0.3 Mpa but
is not necessarily limited to 0.3 MPa, and may be set to a suitable value in accordance
with the design specifications and installation environment. For example, the threshold
value ΔTh may be set to 0.1 MPa, or may be set to 0.4 MPa.
(8-4) Modification D
[0203] In the aforedescribed embodiment, the controller 50 determined the suitability of
the filled refrigerant amount in the refrigerant circuit RC (whether or not there
is a leakage of the refrigerant) by comparing the detection value of the liquid level
detection sensor 25 (liquid level height Lh) and the reference value Sh. However,
the method of determining the suitability of the filled refrigerant amount in the
refrigerant circuit RC is not necessarily limited thereto, and may be any method provided
it is a method capable of determining the suitability of the filled refrigerant amount
in the refrigerant circuit RC. For example, the suitability of the filled refrigerant
amount in the refrigerant circuit RC may be determined using the detection value of
the intake pressure sensor 21 (intake pressure LP), the detection value of the discharge
pressure sensor 22 (discharge pressure HP), or the detection value of the receiver
outlet temperature sensor 23 (receiver outlet temperature TL).
[0204] A refrigerant leakage sensor capable of detecting a refrigerant leakage by detecting
refrigerant that has leaked may be disposed in either of the heat source unit 10 or
the utilization unit 30, and on the basis of the detection result of the refrigerant
leakage sensor, whether or not there is a leakage of the refrigerant in the refrigerant
circuit RC may be determined. In this case, the transition to the refrigerant leakage
determination mode is made on the occasion of the refrigerant leakage sensor detecting
a refrigerant leakage. That is, the refrigerant circuit RC is divided into the plurality
of refrigerant flow paths, and whether or not there is a leakage of the refrigerant
in each of the refrigerant flow paths is determined on the occasion of the refrigerant
leakage sensor having detected a refrigerant leakage.
(8-5) Modification E
[0205] In the aforedescribed embodiment, in accordance with the input of a refrigerant leakage
determination command, the transition to the filled refrigerant amount determination
mode occurs, and determination of the filled refrigerant amount is performed. However,
the event serving as the trigger for determination of the filled refrigerant amount
being performed is not necessarily limited thereto and can be suitably changed in
accordance with the design specifications and installation environment.
[0206] For example, the determination of the filled refrigerant amount may be performed
at the time of a trial run during construction or maintenance, or during a regular
inspection. That is, it is not always necessary to transit to the filled refrigerant
amount determination mode during operation. The transition to the filled refrigerant
amount determination mode may occur on the occasion of the input of a predetermined
command when operation is stopped, whereby the filled refrigerant amount determination
may be performed.
[0207] Alternatively, with the arrangement of a counter capable of measuring time, the controller
50 (mode control unit 53) may be configured to switch from the normal mode to the
filled refrigerant amount determination mode on the occasion of the passage of a predetermined
time t1 from after the transition to the normal operation mode. In this case, the
controller 50 periodically transitions to the filled refrigerant amount determination
mode. The predetermined time t1 is suitably set in accordance with the design specifications
and installation environment.
(8-6) Modification F
[0208] In the aforedescribed embodiment, for identifying the refrigerant leakage spot in
the refrigerant circuit RC, whether or not there is a leakage of the refrigerant in
the first flow path RP1, the second flow path RP2, and the third flow path RP3 is
determined by detecting a fluctuation in the intake pressure LP.
[0209] However, whether or not there is a leakage of the refrigerant in the first flow path
RP1, the second flow path RP2, and the third flow path RP3 need not be determined
on the basis of the intake pressure LP, and may be determined on the basis of another
value. For example, whether or not there is a leakage of the refrigerant in the first
flow path RP1, the second flow path RP2, and the third flow path RP3 may be determined
by detecting whether or not the discharge pressure HP fluctuates by a percentage exceeding
a predetermined threshold value.
[0210] Alternatively, whether or not there is a leakage of the refrigerant in the first
flow path RP1, the second flow path RP2, and the third flow path RP3 may also be determined
by for example disposing a temperature sensor in the heat source unit 10 for detecting
the temperature of the refrigerant drawn into the compressor 11 (intake temperature
LT) or the temperature of the refrigerant discharged from the compressor 11 (discharge
temperature HT), and detecting whether or not the intake temperature LT or discharge
temperature HT fluctuates by a percentage exceeding a predetermined threshold value.
[0211] Alternatively, a refrigerant state detection sensor that detects the state of the
refrigerant (for example, a pressure sensor that detects the pressure of the refrigerant,
or a temperature sensor that detects the temperature of the refrigerant) may be disposed
in the second flow path RP2 and/or the third flow path RP3, and whether or not there
is a leakage of the refrigerant in the second flow path RP2 and/or the third flow
path RP3 may be determined in accordance with the detection result of the refrigerant
state detection sensor.
(8-7) Modification G
[0212] In the aforedescribed embodiment, the liquid-side closing valve 17 was disposed in
the refrigerant circuit RC as a valve for dividing the first flow path RP1 from the
third flow path RP3, but the heat source-side expansion valve 15 may be made to function
as a valve for dividing the first flow path RP1 and the third flow path RP3. In this
case, it is possible to omit the liquid-side closing valve 17.
(8-8) Modification H
[0213] In the aforedescribed embodiment, the controller 50, which controls the operation
of the refrigeration apparatus 100, was constituted by the heat-source-unit control
unit 26 and each utilization-unit control unit 38 being connected via the communication
line cb1 in the refrigeration apparatus 100. However, the configuration embodiment
of the controller 50 is not necessarily limited thereto and can be suitably changed
in accordance with the design specifications and installation environment. For example,
some or all of the elements included in the controller 50 (the storage unit 51, the
communication unit 52, the mode control unit 53, the actuator control unit 54, the
filled refrigerant amount shortage discriminating unit 55, the display control unit
56, and the refrigerant leakage spot identifying unit 57) do not necessarily need
to be disposed in the heat source unit 10 and/or the utilization unit 30, and may
be arranged in another apparatus in a remote place connected by a communication network,
or may be independently arranged. That is, provided the components included in the
controller 50 (the storage unit 51, the communication unit 52, the mode control unit
53, the actuator control unit 54, the filled refrigerant amount shortage discriminating
unit 55, the display control unit 56, and the refrigerant leakage spot identifying
unit 57) are achievable, the configuration embodiment of the controller 50 is not
particularly limited.
(8-9) Modification I
[0214] In the aforedescribed embodiment, the controller 50 caused the remote controller
40 to output predetermined information as an "information output unit". In particular,
the controller 50 caused the remote controller 40 to output the refrigerant leakage
spot reporting information. On this point, when a refrigerant leakage has occurred,
provided the refrigerant leakage spot reporting information is reportable to the user,
a unit other than the remote controller 40 may be made to function as the "information
output unit".
[0215] For example, by arranging a speaker capable of outputting audio and causing the speaker
to output a predetermined alarm sound or message voice, the speaker may be made to
function as an "information output unit" that outputs the refrigerant leakage spot
reporting information. Also, by arranging a light source such as an LED lamp or the
like and causing the light source to blink or turn on, the light source may be made
to function as an "information output unit" that outputs the refrigerant leakage spot
reporting information. In addition, by arranging a unit capable of outputting the
refrigerant leakage spot reporting information in an apparatus such as a central processing
device disposed at a remote spot separated from the facility or site where the refrigeration
apparatus 100 is applied, the unit may be made to function as the "information output
unit".
(8-10) Modification J
[0216] In the aforedescribed embodiment, only one each of the heat source unit 10 and the
utilization unit 30 were included in the refrigeration apparatus 100. However, the
number of the heat source unit 10 and/or the utilization unit 30 is not limited thereto,
and there may also be a plurality.
[0217] In the aforedescribed embodiment, there was one compressor 11 disposed in the refrigerant
circuit RC. However, the number of the compressor 11 is not limited thereto and there
may also be a plurality thereof.
(8-11) Modification K
[0218] In the aforedescribed embodiment, in the refrigeration apparatus 100, a motor-operated
valve was adopted for the utilization-side expansion valve 32, but the type of valve
is not limited thereto, and for example a temperature sensitive type expansion valve
that operates in accordance with the temperature change of temperature sensitive cylinder
may also be adopted. In this case, a solenoid valve or motor-operated valve may be
disposed in the front stage or rear state of the utilization-side expansion valve
32, and the solenoid valve or motor-operated valve may be switched to the closed state,
so as to divide the second flow path RP2 from the third flow path RP3.
(8-12) Modification L
[0219] In the aforedescribed embodiment, R32 was used as the refrigerant that circulates
in the refrigerant circuit RC. However, the refrigerant used in the refrigerant circuit
RC is not particularly limited. For example, HFO1234yf, HFO1234ze(E), and a mixture
of these refrigerants may be used in place of R32 in the refrigerant circuit RC. An
HFC-type refrigerant such as R407C or R410A may also be used in the refrigerant circuit
RC.
INDUSTRIAL APPLICABILITY
[0220] The present invention can be used as a method of identifying a refrigerant leakage
spot that identifies a refrigerant leakage spot in a refrigeration apparatus including
a refrigerant circuit.
REFERENCE SIGNS LIST
[0221]
- 10, 10a:
- heat source unit
- 11:
- compressor
- 12:
- heat source-side heat exchanger
- 13:
- receiver
- 14:
- supercooler
- 15:
- heat source-side expansion valve (valve)
- 16:
- injection valve
- 17:
- liquid-side closing valve (valve)
- 18:
- gas-side closing valve
- 19:
- check valve
- 20:
- heat source-side fan
- 21:
- intake pressure sensor (refrigerant state detection sensor)
- 22:
- discharge pressure sensor (refrigerant state detection sensor)
- 23:
- receiver outlet temperature sensor (refrigerant state detection sensor)
- 24:
- heat source-side air sensor
- 25:
- liquid level detection sensor (refrigerant state detection sensor)
- 26:
- heat-source-unit control unit
- 30, 30a:
- utilization unit
- 31:
- heating pipe
- 32:
- utilization-side expansion valve (valve)
- 32a:
- capillary tube
- 33:
- utilization-side heat exchanger
- 34:
- drain pan
- 36:
- utilization-side fan
- 38:
- utilization-unit control unit
- 40:
- remote controller (information output unit)
- 50:
- controller
- 51:
- storage unit
- 52:
- communication unit
- 53:
- mode control unit
- 54:
- actuator control unit
- 55:
- filled refrigerant amount shortage discriminating unit
- 56:
- display control unit
- 57:
- refrigerant leakage spot identifying unit
- 71:
- first gas-side on/off valve (valve)
- 72:
- second gas-side on/off valve (valve)
- 73:
- third gas-side on/off valve (valve)
- 100, 200:
- refrigeration apparatus
- G1:
- gas refrigerant communication pipe
- L1:
- liquid refrigerant communication pipe
- P1:
- first heat source-side gas refrigerant pipe
- P2:
- heat source-side liquid refrigerant pipe
- P3:
- second heat source-side gas refrigerant pipe
- P4:
- injection pipe
- P5:
- first utilization-side liquid refrigerant pipe
- P6:
- second utilization-side liquid refrigerant pipe
- P7:
- utilization-side gas refrigerant pipe
- P8:
- third heat source-side gas refrigerant pipe
- P9:
- fourth heat source-side gas refrigerant pipe
- P10:
- third utilization-side liquid refrigerant pipe
- RC, RC1:
- refrigerant circuit
- RP1, RP1':
- first flow path (first refrigerant flow path)
- RP2, RP2':
- second flow path (second refrigerant flow path)
- RP3:
- third flow path (second refrigerant flow path)
- cb1:
- communication line
CITATION LIST
PATENT LITERATURE
[0222]
<Patent Document 1> Japanese Laid-open Patent Publication No. 2014-95514
<Patent Document 2> Japanese Laid-open Patent Publication No. 2011-226704
<Patent Document 3> Japanese Laid-open Patent Publication No. 2013-40730