FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
AIRTIGHTNESS EVALUATION DEVICE;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
Technical Field
5 [0001] The present invention relates to a technique of evaluating airtightness in a
refrigeration cycle system.
Background Art
[0002] A refrigeration cycle system such as an air-conditioning device and a
refrigeration device, which utilizes a refrigeration cycle is widely used all over the
10 world and is indispensable for life of modern people. However, since a refrigerant
sealed in the refrigeration cycle has a greenhouse effect and is flammable, its adverse
effect caused by a leak poses an issue.
In Japan, "Act on Rational Use and Appropriate Management of CFCs" was
enforced in April 2015, making it mandatory to inspect and record a refrigerant leak and
15 to report a case of leak.
[0003] When sealing a refrigerant in a refrigeration cycle system in installation and
repair, it is necessary to make sure before sealing that there is no leak in the
refrigeration cycle.
Nitrogen pressure leak test is widely used as a method of determining whether
20 a leak exists or not. In the nitrogen pressure leak test, nitrogen is sealed and
pressurized in a refrigeration cycle before sealing a refrigerant. Airtightness of the
refrigeration cycle is evaluated based on a pressure change observed until a lapse of a
certain period of time. If the airtightness is higher than a reference, it is determined
that there is no leak.
25 [0004] In Patent Literature 1, a pipe inserter for connecting a nitrogen cylinder is used
3
to improve work efficiency of the nitrogen pressure leak test.
Citation List
Patent Literature
[0005] Patent Literature 1: JPH 07-286932 A
5 Summary of Invention
Technical Problem
[0006] In a nitrogen pressure leak test, in order to measure a pressure of pressurized
nitrogen, it is necessary to use a pressure gauge that can measure a high pressure. The
pressure gauge capable of measuring a high pressure has a low resolution and
10 accordingly cannot readily measure a small change in pressure. In the nitrogen
pressure leak test, when an amount of leakage is very small, it takes time before the
pressure drops sufficiently so that the drop can be definitely measured by the pressure
gauge. Therefore, in the nitrogen pressure leak test, it takes a long time such as one
day to evaluate airtightness after nitrogen is sealed and pressurized.
15 In Patent Literature 1, although a time taken until start of the pressurized leak
test can be reduced, it is impossible to shorten a time costed by the nitrogen pressurized
leak test itself which accounts for most of the total of a series of working hours.
An objective of the present invention is to enable evaluation of airtightness in a
refrigeration cycle system with using a simple and easy method.
20 Solution to Problem
[0007] An airtightness evaluation device for a refrigeration cycle system according to
the present invention includes:
a differential pressure gauge to output a pressure difference between two
spaces connected to two joints;
25 a system joint for connecting the refrigeration cycle system to one joint of the
4
differential pressure gauge;
a pressure vessel connected to the other joint of the differential pressure gauge;
a bypass circuit to connect the system joint and the pressure vessel to each
other with bypassing the differential pressure gauge;
5 a bypass valve to open/close the bypass circuit; and
a supply source joint for supplying a pressurization gas to the pressure vessel.
Advantageous Effects of Invention
[0008] In the present invention, airtightness of a refrigeration cycle system can be
evaluated on the basis of a differential pressure between a pressure vessel and a
10 refrigeration cycle system. To measure the differential pressure, a pressure gauge
capable of measuring a high pressure is not necessary, and a differential pressure gauge
that can measure a small differential pressure can be used. Therefore, it is possible to
evaluate the airtightness without requiring long-time waiting.
Brief Description of Drawings
15 [0009] Fig. 1 is a configuration diagram of an airtightness evaluation device 10 for a
refrigeration cycle system 50 according to Embodiment 1.
Fig. 2 is a diagram explaining how to connect the airtightness evaluation
device 10 to the refrigeration cycle system 50 according to Embodiment 1.
Fig. 3 is a flowchart illustrating operations of the airtightness evaluation device
20 10 according to Embodiment 1.
Fig. 4 is a diagram explaining how to connect an airtightness evaluation device
10 to a refrigeration cycle system 50 according to Modification 2.
Fig. 5 is a configuration diagram of an airtightness evaluation device 10 for a
refrigeration cycle system 50 according to Modification 4.
25 Fig. 6 is a diagram explaining how to connect the airtightness evaluation
5
device 10 to the refrigeration cycle system 50 according to Modification 4.
Fig. 7 is a configuration diagram of an airtightness evaluation device 10 for a
refrigeration cycle system 50 according to Embodiment 2.
Description of Embodiments
5 [0010] Embodiment 1.
*** Description of Configurations ***
A configuration of an airtightness evaluation device 10 for a refrigeration cycle
system 50 according to Embodiment 1 will be described with referring to Fig. 1.
The airtightness evaluation device 10 is provided with a differential pressure
10 gauge 11, a system joint 12, a pressure vessel 13, a bypass circuit 14, a supply source
joint 15, a bypass valve 161, a pressure adjusting valve 162, a gas supply valve 163, a
source-pressure gauge 171, an adjusted-pressure gauge 172, an applied-pressure gauge
173, a thermometer 18, pipes 21, 22, and 23, and a control device 40.
[0011] The differential pressure gauge 11 outputs a pressure difference between two
15 spaces connected to two joints. The system joint 12 for connecting the refrigeration
cycle system 50 is connected to one joint 111 of the differential pressure gauge 11 via
the pipe 21. The system joint 12 has two joints; a joint 121 and a joint 122 which are
to be connected to different positions of the refrigeration cycle system 20. The
pressure vessel 13 is connected to the other joint 112 of the differential pressure gauge
20 11 via the pipe 22.
[0012] The bypass circuit 14 connects the system joint 12 and the pressure vessel 13
to each other with bypassing the differential pressure gauge 11. Specifically, the
bypass circuit 14 connects a connection point 31 of the pipe 21 and a connection point
32 of the pipe 22 to each other, the pipe 21 connecting the differential pressure gauge 11
25 and the system joint 12 to each other, the pipe 22 connecting the differential pressure
6
gauge 11 and the pressure vessel 13 to each other.
The bypass circuit 14 has the bypass valve 161 which opens/closes the bypass
circuit 14.
[0013] The supply source joint 15 for supplying a pressurization gas to the pressure
5 vessel 13 is connected, via the pipe 23, to a connection point 33 of the pipe 22 that
connects the differential pressure gauge 11 and the pressure vessel 13 to each other. A
gas cylinder or the like in which the pressurization gas is sealed is connected to the
supply source joint 15.
The pipe 23 has the pressure adjusting valve 162 for adjusting a pressure of the
10 gas to be supplied to the pressure vessel 13, and the gas supply valve 163 for switching
supply on/off of the gas to the pressure vessel 13.
[0014] The source-pressure gauge 171 is designed to measure a pressure in the pipe
23 between the supply source joint 15 and the pressure adjusting valve 162. That is,
the source-pressure gauge 171 measures the pressure of the gas supplied from the
15 supply source joint 15. The adjusted-pressure gauge 172 is designed to measure the
pressure in the pipe 23 between the pressure adjusting valve 162 and the gas supply
valve 163. That is, the adjusted-pressure gauge 172 measures the pressure of the gas
having passed through the pressure adjusting valve 162. The applied-pressure gauge
173 is designed to measure the pressure in the pipe 23 between the gas supply valve 163
20 and the connection point 33. That is, the applied-pressure gauge 173 measures the
pressure applied to the pressure vessel 13 and the refrigeration cycle system 50.
A configuration formed of the pressure adjusting valve 162, the sourcepressure gauge 171, and the adjusted-pressure gauge 172 is the same as a configuration
generally referred to as a pressure adjusting unit (regulator).
25 [0015] The differential pressure gauge 11 is different from the source-pressure gauge
7
171, the adjusted-pressure gauge 172, and the applied-pressure gauge 173 in terms of a
range of a pressure to measure.
Each of the source-pressure gauge 171, the adjusted-pressure gauge 172, and
the applied-pressure gauge 173 is required to be able to measure a pressure to be applied
5 to the refrigeration cycle system 50 when evaluating the airtightness. In evaluation of
the airtightness of the refrigeration cycle system 50, a pressure zone of 2 to 10 MPa
(megapascal) is used.
As opposed to this, the differential pressure gauge 11 is not required to be able
to measure the pressure to be applied to the refrigeration cycle system 50 when
10 evaluating the airtightness, since the differential pressure gauge 11 measures a pressure
difference between the refrigeration cycle system 50 and the pressure vessel 13. The
differential pressure gauge 11 may be able to measure a pressure that is 1/5 or less and
1/50 or more of the pressure to be applied to the refrigeration cycle system 50 when
evaluating the airtightness. In other words, a maximum value of the pressure that can
15 be measured by the differential pressure gauge 11 may be 1/5 or less and 1/50 or more
of a pressure that can be measured by the source-pressure gauge 171, the adjustedpressure gauge 172, and the applied-pressure gauge 173. For example, when the
maximum value of the pressure that can be measured by the source-pressure gauge 171,
the adjusted-pressure gauge 172, and the applied-pressure gauge 173 is 5 MPa, the
20 maximum value of the pressure that can be measured by the differential pressure gauge
11 may be 250 kPa (kilopascal).
[0016] The pipes 21, 22, and 23 are made of copper or aluminum that can withstand
the pressure applied to the refrigeration cycle system 50 when evaluating the
airtightness. The pipes 21, 22, and 23 may be constituted of a hose or the like that can
25 withstand the pressure applied to the refrigeration cycle system 50 when evaluating the
8
airtightness.
[0017] The control device 40 is a computer such as a microcomputer. The control
device 40 is provided with a valve control unit 41 and a measurement unit 42 as
function constituent elements. Functions of the valve control unit 41 and measurement
5 unit 42 are implemented by software. Alternatively, the functions of the valve control
unit 41 and measurement unit 42 may be implemented by hardware such as a Field
Programmable Gate Array (FPGA).
[0018] How to connect the airtightness evaluation device 10 to the refrigeration cycle
system 50 according to Embodiment 1 will be described with referring to Fig. 2.
10 In Embodiment 1, the refrigeration cycle system 50 is an air-conditioning
system provided with an outdoor unit 51 and an indoor unit 52 that constitute a vapor
compression type refrigeration cycle. The outdoor unit 51 and the indoor unit 52 are
connected to each other via a liquid pipe 53 through which a liquid refrigerant flows,
and via a gas pipe 54 through which a gas refrigerant flows.
15 The outdoor unit 51 is provided with a compressor, a heat exchanger, and so
on which are connected in series via a refrigerant pipe. The outdoor unit 51 has a lowpressure service port 511 in a low-pressure pipe which is on a suction side of the
compressor, and a high-pressure service port 512 in a high-pressure pipe which is on a
discharge side of the compressor. The low-pressure service port 511 and the high20 pressure service port 512 are utilized for connecting a pressure gauge to measure an
internal pressure, and for connecting a gas cylinder to inject a gas into the outdoor unit
51.
Also, the outdoor unit 51 has a liquid operating valve 513 near a connecting
portion with the liquid pipe 53, and a gas operating valve 514 near a connecting portion
25 with the gas pipe 54.
9
[0019] Of the airtightness evaluation device 10, the joint 121 and the joint 122 are
connected to the low-pressure service port 511 and the high-pressure service port 512,
respectively, via connecting parts 55 and 56 such as hoses and pipes. By doing so, the
airtightness evaluation device 10 is connected to the refrigeration cycle system 50.
5 The supply source joint 15 of the airtightness evaluation device 10 is
connected to a nitrogen cylinder 60 via a connecting part 57 such as a hose and a pipe.
Nitrogen is sealed in the nitrogen cylinder 60.
[0020] *** Description of Operations ***
Operations of the airtightness evaluation device 10 according to Embodiment 1
10 will be described with referring to Fig. 3.
An operation procedure of the airtightness evaluation device 10 according to
Embodiment 1 corresponds to an airtightness evaluation method according to
Embodiment 1.
[0021] Note that the liquid operating valve 513 and gas operating valve 514 in the
15 outdoor unit 51 have been opened by an operator or the like. Also, note that the
bypass valve 161, the pressure adjusting valve 162, and the gas supply valve 163 are in
a closed state before the following operations are started.
[0022] In step S11, the valve control unit 41 of the control device 40 opens the bypass
valve 161 and the gas supply valve 163. By doing so, the pressure vessel 13 of the
20 airtightness evaluation device 10 communicates with the outdoor unit 51 and indoor
unit 52 of the refrigeration cycle system 50.
In step S12, the measurement unit 42 measures the pressure with the adjustedpressure gauge 172. Then, the valve control unit 41 adjusts an opening of the pressure
adjusting valve 162 such that the pressure measured by the adjusted-pressure gauge 172
25 is slightly higher than a target pressure. For example, if the target pressure is 2 MPa,
10
the valve control unit 41 adjusts the opening of the pressure adjusting valve 162 such
that the pressure measured by the adjusted-pressure gauge 172 is 2.2 MPa.
In step S13, at a lapse of a predetermined period of time, when nitrogen gas is
supplied from the nitrogen cylinder 60 to the pressure vessel 13, the outdoor unit 51,
5 and the indoor unit 52, the valve control unit 41 closes the gas supply valve 163.
[0023] In step S14, the measurement unit 42 measures the pressure with the appliedpressure gauge 173. If the pressure measured by the applied-pressure gauge 173 is
lower than the target pressure, the measurement unit 42 advances processing to step
S15. On the other hand, if the pressure measured by the applied-pressure gauge 173 is
10 equal to or higher than the target pressure, the measurement unit 42 advances the
processing to step S16.
In step S15, the valve control unit 41 opens the gas supply valve 163 to supply
the nitrogen gas from the nitrogen cylinder 60 to the pressure vessel 13, the outdoor unit
51, and the indoor unit 52 again. Then, at a lapse of a predetermined period of time,
15 the valve control unit 41 brings the processing back to step S13 to close the gas supply
valve 163. With the processing of step S13 to step S15, the pressures in the pressure
vessel 13, outdoor unit 51, and indoor unit 52 can be set to be equal to or higher than the
target pressure.
[0024] In step S16, the control device 40 waits until a wait time of 10 minutes or so
20 elapses, to equalize the pressures in the pressure vessel 13, outdoor unit 51, and indoor
unit 52.
In step S17, the valve control unit 41 closes the bypass valve 161. By doing
so, the pressure vessel 13 of the airtightness evaluation device 10 is disconnected from
the refrigeration cycle system 50. Accordingly, if a nitrogen gas leak exists on the
25 refrigeration cycle system 50 side, a differential pressure is measured by the differential
11
pressure gauge 11.
[0025] In step S18, the measurement unit 42 measures the differential pressure
between the pressure vessel 13 and the refrigeration cycle system 50 with the
differential pressure gauge 11. As for the differential pressure to be measured, the
5 pressure of the pressure vessel 13 serves as a reference. That is, if a nitrogen gas leak
exists on the refrigeration cycle system 50 side, the differential pressure takes a positive
value. If a nitrogen gas leak exists on the pressure vessel 13 side, the differential
pressure takes a negative value.
The measurement unit 42 determines whether or not the measured differential
10 pressure is higher than 0 MPa. If the measured differential pressure is higher than 0
MPa, the measurement unit 42 advances the processing to step S19. On the other
hand, if the measured differential pressure is equal to or lower than 0 MPa, the
measurement unit 42 advances the processing to step S20.
[0026] In step S19, the measurement unit 42 determines that a nitrogen gas leak exists
15 on the refrigeration cycle system 50 side. On the other hand, in step S20, the
measurement unit 42 determines that a nitrogen gas leak does not exist on the
refrigeration cycle system 50 side.
[0027] In the above description, in step S18, 0 MPa is used as a reference value, and
whether a leak exists or not is determined in accordance with whether the differential
20 pressure is larger than the reference value or not. However, the measurement unit 42
may correct the reference value in accordance with a temperature in the pressure vessel
13 measured by the thermometer 18.
[0028] How the reference value is corrected will be described.
For example, with a gas like nitrogen that exhibits behavior close to that of an
25 ideal gas, the temperature and the pressure follow a Boyle-Charles' law. The Boyle-
12
Charles' law is given by expression (1) using a pressure P, a volume V, a temperature T,
and a constant k.
Expression (1) P = kꞏT/V
[0029] Assume that a pressure in an equal-pressure state realized in step S16 is
5 expressed as P0 and that a temperature measured by the thermometer 18 in the equalpressure state is expressed as T0. Here, assume that during a transition from step S16
to step S18, the pressure vessel 13 is influenced by a surrounding temperature change
and accordingly the temperature measured by the thermometer 18 changes to T1. The
pressure vessel 13 has a smaller internal volume and a smaller heat capacity when
10 compared to the refrigeration cycle system 50 with which the pressure is to be
compared, and accordingly the pressure vessel 13 tends to be influenced by the
temperature change.
Now, about a pressure P1 in the pressure vessel 13, expression (2) holds.
Expression (2) P1 = P0ꞏT1/T0
15 [0030] Therefore, even if there is no nitrogen gas leak, a differential pressure Tc
measured by the differential pressure gauge 11 satisfies expression (3).
Expression (3) Tc = P0 - P1 = P0∙( T0 - T1)/T0
[0031] In view of this, the measurement unit 42 decides Tc, not 0 MPa, as the
reference value to be used in step S18. This enables high-accuracy airtightness
20 evaluation regardless of a temperature change that occurs the operations of the
airtightness evaluation device 10.
[0032] *** Effect of Embodiment 1 ***
As described above, the airtightness evaluation device 10 according to
Embodiment 1 evaluates airtightness of the refrigeration cycle system 50 on the basis of
25 the differential pressure with respect to the pressure vessel 13. To measure the
13
differential pressure, a pressure gauge capable of measuring a high pressure is not
necessary, and a differential pressure gauge that can measure a small differential
pressure can be used. Therefore, it is possible to evaluate the airtightness without
requiring long-time waiting.
5 [0033] Also, the airtightness evaluation device 10 according to Embodiment 1
corrects the refence value used for airtightness evaluation in accordance with the
internal temperature of the pressure vessel 13. Hence, high-accuracy airtightness
evaluation is possible regardless of a temperature change that occurs during the
operations of the airtightness evaluation device 10.
10 [0034] Also, in the airtightness evaluation device 10 according to Embodiment 1,
instruments such as the differential pressure gauge 11 and the pressure vessel 13 are
integrated. Therefore, the airtightness of the airtightness evaluation device 10 can be
improved by, for example, welding connecting portions of the instruments. Hence,
high-accuracy airtightness evaluation is possible.
15 On a site where airtightness evaluation is performed with using instruments
such as the differential pressure gauge 11 and the pressure vessel 13 as different
configurations that are not integrated, flare-processed pipes may be connected. In this
case, however, the airtightness in the constituent elements of the airtightness evaluation
device 10 decreases, and the accuracy of the airtightness evaluation decreases. Also, a
20 number of work man-hours at the site increases.
[0035] There is a case where the refrigeration cycle system 50 has a solenoid valve or
a check valve. Then, if a pressure is applied only from either one or the other of the
low-pressure side and the high-pressure side, it may be difficult to equalize the pressure.
Even in a case where a solenoid valve or a check valve is not provided, when an
25 opening of an expansion valve is small at the time the refrigeration cycle system 50
14
stops operating, if a pressure is applied only from either one or the other of the lowpressure side and the high-pressure side, it takes time before the pressure is equalized.
The joint 121 and the joint 122 in the airtightness evaluation device 10
according to Embodiment 1 are connected to the low-pressure service port 511 and the
5 high-pressure service port 512, respectively. This makes it possible to equalize the
pressure in the refrigeration cycle system 50 even if a solenoid valve or a check valve is
provided. Also, even if the opening of the expansion valve is small at the time the
refrigeration cycle system 50 stops operating, it is possible to equalize the pressure in
the refrigeration cycle system 50 within a short period of time.
10 [0036] *** Other Configurations ***
< Modification 1 >
In Embodiment 1, airtightness evaluation is performed in a state where the
liquid operating valve 513 and the gas operating valve 514 are open. As the liquid
operating valve 513 and the gas operating valve 514 are open, the outdoor unit 51 and
15 the indoor unit 52 communicate with each other. Therefore, whether nitrogen gas
leaks or not from at least either one or the other of the outdoor unit 51 and the indoor
unit 52 is determined.
If it is determined that a leak exists, the liquid operating valve 513 and the gas
operating valve 514 may be closed, and after that the processing illustrated in Fig. 3
20 may be executed. By closing the liquid operating valve 513 and the gas operating
valve 514, the outdoor unit 51 and the indoor unit 52 are disconnected from each other.
Thus, the liquid operating valve 513 and the gas operating valve 514 are closed, and
after that the processing illustrated in Fig. 3 is executed, so that whether nitrogen gas
leaks or not from the outdoor unit 51 can be determined.
25 [0037] < Modification 2 >
15
In Embodiment 1, the airtightness evaluation device 10 is connected to the
low-pressure service port 511 and high-pressure service port 512 of the refrigeration
cycle system 50.
If it is determined that a leak exists, the airtightness evaluation device 10 may
5 be connected to the liquid operating valve 513 and gas operating valve 514 of the
refrigeration cycle system 50, then the liquid operating valve 513 and the gas operating
valve 514 may be closed, as illustrated in Fig. 4, and after that the processing illustrated
in Fig. 3 may be performed. The liquid operating valve 513 and the gas operating
valve 514 have ports for measuring the pressure. When the liquid operating valve 513
10 and the gas operating valve 514 are closed, the ports communicate with the indoor unit
52 side. Thus, the airtightness evaluation device 10 is connected to the liquid
operating valve 513 and the gas operating valve 514 and then the liquid operating valve
513 and the gas operating valve 514 are closed, and after that the processing illustrated
in Fig. 3 is executed, so that whether nitrogen gas leaks or not from the indoor unit 52
15 can be determined.
[0038] In a case where a service port for measuring the pressure and a valve for
dividing the refrigeration cycle are formed at various positions of the refrigeration cycle
system 50, the connecting positions of the airtightness evaluation device 10 and the
dividing positions of the refrigeration cycle are changed, and after that the processing
20 illustrated in Fig. 3 is executed, so that a location where the leak exists can be limited.
[0039] < Modification 3 >
In Embodiment 1, the refrigeration cycle system 50 is an air-conditioning
system. However, the refrigeration cycle system 50 is not limited to an airconditioning system, but can be a refrigeration system such as a refrigerator.
25 [0040] < Modification 4 >
16
In Embodiment 1, the system joint 12 has the two joints: the joint 121 and the
joint 122 which are to be connected to different positions. However, if a solenoid
valve or a check valve is not installed in the refrigeration cycle system 50, the system
joint 12 may have only one joint 123, as illustrated in Fig. 5. In this case, the joint 123
5 is connected to the low-pressure service port 511 of the refrigeration cycle system 50, as
illustrated in Fig. 6. Alternatively, the joint 123 may be connected to the high-pressure
service port 512 of the refrigeration cycle system 50.
With this configuration, it may take time before the pressure in the
refrigeration cycle system 50 is equalized.
10 [0041] Embodiment 2.
A pressure vessel 13 is implemented by a pipe 22. In this respect,
Embodiment 2 is different from Embodiment 1. In Embodiment 2, this difference will
be described, and the same features will not be described.
[0042] In Embodiment 1, the pressure vessel 13 is connected to the differential
15 pressure gauge 11 via the pipe 22. However, in Embodiment 2, a closed space defined
by a pipe 22 is utilized as a pressure vessel 13, as illustrated in Fig. 7. More precisely,
a region in the pipe 22 between a differential pressure gauge 11 and a gas supply valve
163 is utilized as the pressure vessel 13.
[0043] Since the pressure vessel 13 is implemented by the pipe 22 as described above,
20 an airtightness evaluation device 10 can be made compact. Thus, the operation
workability at a site where airtightness evaluation is performed can be improved.
[0044] Since the pressure vessel 13 becomes compact, it tends to be influenced by a
surrounding temperature change. However, by correcting a reference value in
accordance with a temperature measured by a thermometer 18, high-accuracy
25 airtightness evaluation can be performed.
17
[0045] Embodiments and modifications of the present invention have been described
above. Some of the embodiments and modifications may be practiced by combination.
Also, one or some of the embodiments and modifications may be practiced partly.
Note that the present invention is not limited to the above embodiments and
5 modifications, but various changes can be made to the present invention as needed.
Reference Signs List
[0046] 10: airtightness evaluation device; 11: differential pressure gauge; 111: joint;
112: joint; 12: system joint; 121: joint; 122: joint; 123: joint; 13: pressure vessel; 14:
bypass circuit; 15: supply source joint; 161: bypass valve; 162: pressure adjusting valve;
10 163: gas supply valve; 171: source-pressure gauge; 172: adjusted-pressure gauge; 173:
applied-pressure gauge; 18: thermometer; 21: pipe; 22: pipe; 23: pipe; 31: connection
point; 32: connection point; 33: connection point; 40: control device; 41: valve control
unit; 42: measurement unit; 50: refrigeration cycle system; 51: outdoor unit; 511: lowpressure service port; 512: high-pressure service port; 513: liquid operating valve; 514:
15 gas operating valve; 52: indoor unit; 53: liquid pipe; 54: gas pipe; 55: connecting part;
56: connecting part; 57: connecting part; 60: nitrogen cylinder.
18
We Claim :
[Claim 1] An airtightness evaluation device for a refrigeration cycle system, the
airtightness evaluation device comprising:
a differential pressure gauge to output a pressure difference between two
5 spaces connected to two joints;
a system joint for connecting the refrigeration cycle system to one joint of the
differential pressure gauge;
a pressure vessel connected to the other joint of the differential pressure gauge;
a bypass circuit to connect the system joint and the pressure vessel to each
10 other with bypassing the differential pressure gauge;
a bypass valve to open/close the bypass circuit; and
a supply source joint for supplying a pressurization gas to the pressure vessel.
[Claim 2] The airtightness evaluation device for the refrigeration cycle system
according to claim 1,
15 wherein the system joint has two joints to be connected to different positions
of the refrigeration cycle system.
[Claim 3] The airtightness evaluation device for the refrigeration cycle system
according to claim 2,
wherein the two joints are connected, one to a high-pressure side and the other
20 to a low-pressure side, of the refrigeration cycle system.
[Claim 4] The airtightness evaluation device for the refrigeration cycle system,
according to any one of claims 1 to 3,
wherein pressure vessel is a pipe connected to the other joint of the differential
pressure gauge.
25 [Claim 5] The airtightness evaluation device for the refrigeration cycle system
19
according to any one of claims 1 to 4, the airtightness evaluation device for the
refrigeration cycle system further comprising
a pressure adjusting valve for adjusting a pressure of the gas to be supplied to
the pressure vessel, and a gas supply valve for switching supply on/off of the gas to the
5 pressure vessel, the pressure adjusting valve and the gas supply valve being provided
between the supply source joint and the pressure vessel.
[Claim 6] The airtightness evaluation device for the refrigeration cycle system
according to any one of claims 1 to 5, the airtightness evaluation device for the
refrigeration cycle system further comprising
10 a thermometer to measure a temperature of the gas accumulated in the pressure
vessel.
[Claim 7] The airtightness evaluation device for the refrigeration cycle system
according to any one of claims 1 to 6,
wherein the differential pressure gauge has a measurement range with a
15 maximum value that is 1/5 or less of a pressure of the gas to be supplied to the pressure
vessel.