Patent Grant
11781795
This application is a U.S. National Stage Application of International Application No. PCT/JP2019/014638, filed on Apr. 2, 2019, the contents of which are incorporated herein by reference.
The present disclosure relates to an air-conditioning apparatus that uses combustible refrigerant.
In recent years, an air-conditioning apparatus is proposed that uses combustible refrigerant having a small global warming potential, such as R32, as refrigerant used in place of R410A. The specific gravity of combustible refrigerant is greater than the specific gravity of air and hence, refrigerant is likely to stagnate.
In some air-conditioning apparatus, a refrigerant leakage detection sensor may be provided to an indoor unit. When the refrigerant leakage detection sensor detects refrigerant leakage, a control unit closes the valve of a refrigerant pipe of a refrigeration cycle to prevent refrigerant from being supplied to the indoor unit where leakage is occurring (see Patent Literature 1, for example).
In some technique, when a refrigerant leakage detection sensor detects leakage of refrigerant, a control unit closes the valve of a refrigerant pipe of a refrigeration cycle. With such an operation, the air-conditioning apparatus is configured to retain refrigerant in the outdoor unit. As a result, it is possible to eliminate leakage of refrigerant from the indoor unit.
Usually, refrigerant that cycles through the refrigeration cycle is filled in the outdoor unit. Depending on the number of indoor units connected and the length of the refrigerant pipe, additional refrigerant may be required and, in such a case, the amount of refrigerant sealed may exceed the amount of refrigerant filled in the outdoor unit.
As a result, the amount of refrigerant in the air-conditioning apparatus may exceed the amount of refrigerant shipped with the air-conditioning apparatus. When the amount of refrigerant in the air-conditioning apparatus is increased as described above, there is a problem in that all the refrigerant cannot be retained in the outdoor unit. Further, when the valve of the refrigerant pipe is rapidly opened, the concentration of leaked refrigerant in the indoor space is drastically increased.
The present disclosure has been made in view of the above-mentioned circumstances, and it is an object of the present disclosure to provide an air-conditioning apparatus configured to reduce the concentration of leaked refrigerant in the indoor space at a low level even in the case where refrigerant cannot be retained in the outdoor unit.
According to a first aspect, an air-conditioning apparatus of an embodiment includes a first indoor unit included in a single refrigeration cycle and an outdoor unit connected to the first indoor unit via a first refrigerant pipe, and the outdoor unit is included in the single refrigeration cycle. The first indoor unit is provided with a first refrigerant leakage sensor configured to detect leakage of refrigerant flowing through the first refrigerant pipe and a concentration of leaked refrigerant, and the outdoor unit includes a compressor configured to compress the refrigerant flowing through the first refrigerant pipe, a first flow control valve configured to adjust a flow rate of the refrigerant flowing through the first refrigerant pipe, and a control unit configured to stop the compressor and fully close the first flow control valve in a case where leakage of the refrigerant flowing through the first refrigerant pipe is detected by the first refrigerant leakage sensor, and configured to change, after the compressor is stopped and the first flow control valve is fully closed, an opening speed of the first flow control valve to a speed less than an opening speed of the first flow control valve adopted before the leakage of the refrigerant is detected.
According to an embodiment of the present disclosure, a rate at which refrigerant leaks from the first indoor unit is caused to reduce and, as a result, the concentration of leaked refrigerant in the indoor space is caused to reduce at a low level. Further, the amount of refrigerant retained in the outdoor unit is caused to reduce.
Hereinafter, a variable refrigerant flow system according to an embodiment will be described with reference to drawings. In the drawings, identical elements are given the same reference signs, and repeated description will be made only when the repeated description is necessary.
1-1 Configuration
As shown in
In this refrigeration cycle, refrigerant compressed by a compressor 11 of the outdoor unit 2 is caused to cycle to an indoor heat exchanger 21a via an outdoor heat exchanger 12 and a flow control valve 14a, and is caused to return to the compressor 11 again. The refrigerant compressed by the compressor 11 is also caused to cycle to an indoor heat exchanger 21b via the outdoor heat exchanger 12 and a flow control valve 14b, and is caused to return to the compressor 11 again. Further, the refrigerant compressed by the compressor 11 is caused to cycle to an indoor heat exchanger 21c via the outdoor heat exchanger 12 and a flow control valve 14c, and is caused to return to the compressor 11 again. By making use of this refrigeration cycle, the variable refrigerant flow system 1 maintains an indoor unit space at a constant temperature by the state change of cycling refrigerant, that is, by transfer of heat when refrigerant is liquefied and gasified.
In the embodiment, a combustible refrigerant is used as refrigerant. A combustible refrigerant is a refrigerant that combusts when the concentration of refrigerant relative to air falls within a particular range and an ignition source is present Examples of the combustible refrigerant may be a single component refrigerant or a mixed refrigerant of HFO-1234yf (CF3CF═CH2), or a hydrocarbon refrigerant, such as propane (R290). A refrigerant referred to as a slightly flammable refrigerant is also included in the combustible refrigerant in the embodiment.
The outdoor unit 2 includes the compressor 11, the outdoor heat exchanger 12, an outdoor fan 13, and flow control valves 14a to 14c.
The compressor 11 is connected to the refrigerant pipes 10 extending from the respective indoor units 3a to 3c. The compressor 11 compresses refrigerant flowing through the refrigerant pipes 10, extending from the respective indoor units 3a to 3c, and discharges the refrigerant to the outdoor heat exchanger 12.
The outdoor heat exchanger 12 exchanges heat with the outside by using the compressed refrigerant, and discharges the refrigerant that is subjected to heat exchange to the refrigerant pipes 10 connected to the respective indoor units 3a to 3c.
The outdoor fan 13 blows heat generated at the time of exchanging heat by the outdoor heat exchanger 12.
The flow control valves 14a to 14c are also referred to as expansion valves. The flow control valves 14a to 14c are provided to the plurality of respective refrigerant pipes 10 connected to the respective indoor units 3a to 3c. The flow control valve 14a adjusts the flow rate of refrigerant flowing through the refrigerant pipe 10 connected to the indoor unit 3a by changing the opening degree of the valve. The flow control valve 14b adjusts the flow rate of refrigerant flowing through the refrigerant pipe 10 connected to the indoor unit 3b by changing the opening degree of the valve. The flow control valve 14c adjusts the flow rate of refrigerant flowing through the refrigerant pipe 10 connected to the indoor unit 3c by changing the opening degree of the valve. The flow control valves 14a to 14c reduce the pressure of refrigerant compressed by the compressor 11. In the variable refrigerant flow system of the embodiment, the opening degrees of the flow control valves 14a to 14c are individually controlled by a control unit of the outdoor unit 2 described later on the basis of the operation situations of the indoor units.
The flow control valves 14a to 14c are opened at a normal opening speed of the valves. In the embodiment, the normal opening speed of the valves is greater than the opening speed of the flow control valves 14a to 14c adopted after leakage of refrigerant is detected by a refrigerant leakage sensor 31 described later.
The indoor unit 3a includes the indoor heat exchanger 21a, an indoor fan 22a, and a warning unit 32a. The indoor unit 3b includes the indoor heat exchanger 21b, an indoor fan 22b, and a warning unit 32b. The indoor unit 3c includes the indoor heat exchanger 21c, an indoor fan 22c, and a warning unit 32c. The indoor unit 3b further includes the refrigerant leakage sensor 31.
The indoor heat exchanger 21a exchanges heat between refrigerant reduced in pressure by the flow control valve 14a and air in the indoor space around the indoor heat exchanger 21a. The indoor heat exchanger 21b exchanges heat between refrigerant reduced in pressure by the flow control valve 14b and air in the indoor space around the indoor heat exchanger 21b. The indoor heat exchanger 21c exchanges heat between refrigerant reduced in pressure by the flow control valve 14c and air in the indoor space around the indoor heat exchanger 21c. The refrigerant that is subjected to heat exchange is caused to return to the compressor 11 via the respective refrigerant pipes 10 of the indoor units 3a to 3c.
The indoor fan 22a blows air that is in the indoor space and from which heat is removed by the indoor heat exchanger 21a. The indoor fan 22b blows air that is in the indoor space and from which heat is removed by the indoor heat exchanger 21b. The indoor fan 22c blows air that is in the indoor space and from which heat is removed by the indoor heat exchanger 21c.
The warning units 32a to 32c are buzzers or lamps that issue a warning, for example. The warning unit 32a issues a warning in accordance with instructions from a control unit 30a of the indoor unit 3a described later. The warning unit 32b issues a warning in accordance with instructions from a control unit 30b of the indoor unit 3b described later. The warning unit 32c issues a warning in accordance with instructions from a control unit 30c of the indoor unit 3c described later.
The refrigerant leakage sensor 31 is provided in the indoor unit 3b. The refrigerant leakage sensor 31 may be provided on the outside of the indoor unit 3b. The refrigerant leakage sensor 31 detects leakage of refrigerant from a refrigerant circuit forming the refrigeration cycle. Specifically, the refrigerant leakage sensor 31 detects leakage of refrigerant flowing through the refrigerant pipe of the indoor unit 3b. The refrigerant leakage sensor 31 is an oxygen concentration sensor or a combustible gas detection sensor, for example. The refrigerant leakage sensor 31 also detects the concentration of leaked refrigerant.
As shown in
The control unit 5 of the outdoor unit 2 controls the entire variable refrigerant flow system 1. Specifically, the control unit 5 controls the compressor 11, the outdoor fan 13, and the flow control valves 14a to 14c of the outdoor unit 2, and performs processing to achieve the action according to the embodiment.
The control unit 5 is communicably connected to the control units 30a to 30c of the indoor units 3a to 3c. For example, upon receipt of an operation signal transmitted from the control unit 30a, 30b, 30c of the indoor unit 3a, 3b, 3c, the control unit 5 controls the compressor 11, the outdoor fan 13, and the flow control valves 14a to 14c of the outdoor unit 2. Further, the control unit 5 stores a set concentration 5a, which is used in processing of detecting refrigerant leakage.
The control units 30a, 30b, 30c respectively exercise overall control of the indoor units 3a, 3b, 3c. Specifically, the control units 30a, 30b, 30c respectively control the indoor fans 22a, 22b, 22c and the warning units 32a, 32b, 32c, and perform processing to achieve the action according to the embodiment. The control units 30a, 30b, 30c each receive an operation instruction from a remote control or an operation button of the corresponding one of the indoor units 3a, 3b, 3c. The control units 30a, 30b, 30c each output an operation instruction signal to the control unit 5 together with an ID of the corresponding one of the indoor units 3a, 3b, 3c.
Further, when leakage of refrigerant is detected by the refrigerant leakage sensor 31, the control unit 30b of the indoor unit 3b outputs a refrigerant leakage detection signal to the control unit 5.
Each of the control unit 5 of the outdoor unit 2 and the control units 30a to 30c of the indoor units 3a to 3c includes a memory that stores programs and other data, and a central processing unit (CPU). Such a component may be achieved by the CPU executing the program, or may be achieved by a hardware circuit.
The indoor unit 3b corresponds to a first indoor unit. The refrigerant leakage sensor 31 corresponds to a first refrigerant leakage sensor. The flow control valve 14b corresponds to a first flow control valve. The refrigerant pipe 10 connected to the indoor unit 3b corresponds to a first refrigerant pipe. The warning unit 32b corresponds to a first warning unit. The indoor unit 3a, 3c corresponds to a second indoor unit. The flow control valve 14a, 14c corresponds to a second flow control valve. The refrigerant pipe 10 connected to the indoor unit 3a, 3c corresponds to a second refrigerant pipe. The warning unit 32a, 32c corresponds to a second warning unit.
1-2 Action
Next, the action of the refrigerant system of the variable refrigerant flow system according to the embodiment will be described.
After the operation of the indoor units 3a to 3c is started, the control unit 5 determines whether leakage of refrigerant is detected by the refrigerant leakage sensor 31 (S1). Specifically, when the refrigerant leakage sensor 31 detects leakage of refrigerant, the control unit 30b of the indoor unit 3b transmits a refrigerant leakage detection signal to the control unit 5. When the control unit 5 receives the refrigerant leakage detection signal from the control unit 30b, the control unit 5 detects leakage of refrigerant.
When leakage of refrigerant is detected in step S1 (YES in S1), the control unit 5 controls the outdoor unit 2 and the indoor units 3a to 3c. When leakage of refrigerant is not detected in step S1, detection of leakage of refrigerant is continued (NO in S1).
Regarding control of the outdoor unit 2, the operation of the compressor 11 is stopped, the flow control valves 14a to 14c are fully closed, and the operation of the outdoor fan 13 is stopped (S2). Subsequently, the opening speed of the flow control valves 14a to 14c is changed to a speed less than the speed adopted before leakage of refrigerant is detected, and the flow control valves 14a to 14c are opened at the changed speed (S3). That is, in the embodiment, when leakage is detected, the flow control valves 14a to 14c are controlled such that the flow control valves 14a to 14c fully close and then the opening degrees of the flow control valves 14a to 14c gradually increase.
In contrast, regarding the indoor units 3a to 3c, when the control unit 5 receives a refrigerant leakage detection signal from the control unit 30b of the indoor unit 3b, the control unit 5 outputs an abnormality detection signal to each of the control units 30a to 30c of the indoor units 3a to 3c (S4).
When the control units 30a to 30c of the indoor units 3a to 3c receive the abnormality detection signal (YES in S11), the control units 30a to 30c control the warning units 32a to 32c such that a warning is output from each of the warning units 32a to 32c (S12).
In contrast, when the abnormality detection signal is not received in step S11 (NO in S11), monitoring for the receipt of an abnormality detection signal is continued.
As shown in
In such a state, the operation of an outdoor unit is “ON”, a compressor is “ON”, an outdoor fan is “ON”, and flow control valves are “FULLY OPEN”. The opening degree of the flow control valves fluctuates in accordance with the operation from the indoor unit.
When an abnormality occurs at time t2 and refrigerant leakage is detected at time t3, the operation of the outdoor unit is switched to “OFF”, the compressor is switched to “OFF”, the outdoor fan is switched to “OFF”, and the flow control valves are “FULLY CLOSED”. Even after the compressor is stopped, the flow control valves maintain a “FULLY CLOSED” state and hence, there is no possibility that refrigerant flows into the indoor unit.
When an abnormality occurs at time t2 and refrigerant leakage is detected at time t3, the operation of the outdoor unit is switched to “OFF”, the compressor is switched to “OFF”, and the outdoor fan is switched to “OFF” in the same manner as
1-3 Advantageous Effects
According to the embodiment, after refrigerant leakage is detected by the refrigerant leakage sensor 31, the operation of the compressor 11 is stopped, and the flow control valves 14a to 14c are “FULLY CLOSED”. Subsequently, the opening speed of the flow control valves 14a to 14c is changed to a speed less than the speed adopted before leakage of refrigerant is detected. With such an operation, the rate of leakage from the indoor unit where leakage is occurring is caused to reduce. As a result, the concentration of leaked refrigerant in the indoor space is caused to reduce to a low level.
2 Modification
2-1 Modification 1
In the embodiment, when leakage of refrigerant is detected, the flow control valves 14a to 14c are “FULLY CLOSED” and, subsequently, the opening speed of the flow control valves 14a to 14c may be decided on the basis of the concentration of leaked refrigerant.
As shown in
Next, the flow control valves 14a to 14c are opened at the decided speed (S22).
With such operations, the rate of leakage from the indoor unit where leakage is occurring is caused to be set to an appropriate rate. As a result, the concentration of leaked refrigerant in the indoor space is caused to reduce to a low level.
2-2 Modification 2
In the embodiment, when leakage of refrigerant is detected, the flow control valves 14a to 14c are “FULLY CLOSED” and, subsequently, the opening speed of the flow control valves 14a to 14c may be decided on the basis of the set concentration.
As shown in
When the concentration of leaked refrigerant is lower than the set concentration (NO in S31), the flow control valves 14a to 14c are opened at a first speed (S32). When the concentration of leaked refrigerant is higher than or equal to the set concentration (YES in S31), the flow control valves 14a to 14c are opened at a second speed (S33). The second speed is greater than the first speed.
With such operations, the rate of leakage from the indoor unit where leakage is occurring is caused to be set to an appropriate rate. As a result, the concentration of leaked refrigerant in the indoor space is caused to reduce to a low level.
2-3 Modification 3
In the embodiment, when leakage of refrigerant is detected, the flow control valves 14a to 14c are “FULLY CLOSED” and, subsequently, the opening speed of the flow control valves 14a to 14c may be controlled such that the concentration of leaked refrigerant is equal to a set concentration.
As shown in
When it is determined in step S41 that the concentration of leaked refrigerant is the set concentration (YES in S41), the operation of the outdoor unit 2 is stopped. In contrast, when it is determined in step S41 that the concentration of leaked refrigerant is not the set concentration (NO in S41), the opening speed of the flow control valves 14a to 14c is decided such that the concentration of leaked refrigerant is equal to the set concentration (S42). Then, the flow control valves 14a to 14c are opened at the decided speed (S43), and the processing returns to step S41.
With such operations, it is possible to maintain a constant concentration of leaked refrigerant in the indoor space, and the concentration of leaked refrigerant in the indoor space is caused to reduce to a low level.
2-4 Modification 4
In the embodiment, when leakage of refrigerant is detected, an operation signal for operation or other performance transmitted from the indoor unit 3a, 3b, 3c may be overridden.
As shown in
When it is determined in step S45 that the operation signal for operation or other performance is received from the control unit 30a, 30b, 30c of the indoor unit 3a, 3b, 3c (YES in S45), the control unit 5 overrides the received operation signal (S46). That is, even when the control unit 5 receives the operation signal, the control unit 5 does not exercise control in accordance with the operation signal. In contrast, when the operation signal is not received (NO in S45), the control unit 5 stops the operation of the outdoor unit 2.
With such operations, it is possible to reduce the amount of refrigerant flowing into an indoor unit having leakage due to operation of the outdoor unit and hence, the concentration of leaked refrigerant in the indoor space is caused to reduce to a low level.
2-5 Modification 5
In the embodiment, a configuration may be adopted where, in addition to the indoor unit 3b, the refrigerant leakage sensor 31, used as a second refrigerant leakage sensor, is also provided to each of the indoor units 3a, 3c to specify an indoor unit where refrigerant leakage occurs, the opening speed of the flow control valve of the refrigerant pipe 10 of the specified indoor unit is changed, and the operation of the other indoor units is continued.
After the operation of the indoor units 3a to 3c is started, the control unit 5 determines whether leakage of refrigerant is detected by one of the refrigerant leakage sensors 31 provided to the indoor units 3a to 3c (S51).
When it is determined in step S51 that leakage of refrigerant is detected by one of the refrigerant leakage sensors 31 provided to the indoor units 3a to 3c (YES in S51), the control unit 5 specifies the refrigerant leakage sensor 31 that has detected leakage of refrigerant (S52). For example, the control unit 5 specifies which indoor unit includes the refrigerant leakage sensor by the ID applied to a refrigerant leakage detection signal.
In contrast, when it is determined that leakage of refrigerant is not detected by any of the refrigerant leakage sensors 31 provided to the indoor units 3a to 3c (NO in S51), monitoring for leakage of refrigerant is continued.
Next, the control unit 5 controls the outdoor unit 2 and the indoor units 3a to 3c.
Regarding control of the outdoor unit 2, the flow control valve of the indoor unit including the specified refrigerant leakage sensor is fully closed (S53).
Subsequently, the opening speed of the flow control valve corresponding to the specified refrigerant leakage sensor is changed to a speed less than the speed adopted before leakage of refrigerant is detected, and the flow control valve corresponding to the specified refrigerant leakage sensor is opened at the changed speed (S54). That is, in the embodiment, when leakage is detected, the flow control valve of the indoor unit including the specified refrigerant leakage sensor is fully closed, and the opening degree of the flow control valve is controlled such that the opening degree of the flow control valve gradually increases.
In contrast, when the control unit 5 receives a refrigerant leakage detection signal, the control unit 5 outputs an abnormality detection signal to the control units of the other indoor units except for the specified indoor unit (S55).
Next, it is determined whether an operation signal for operation or other performance is received from another indoor unit (S56). When it is determined that the operation signal is received (YES in S56), the received operation signal is overridden (S57). That is, even when the control unit 5 receives an operation signal, the control unit 5 does not exercise control in accordance with the operation signal. In contrast, when the operation signal is not received (NO in S56), the processing returns to step S51.
With such operations, even if refrigerant leakage occurs in a specific indoor unit, the other indoor units are configured to continue the operation.
In the embodiment, the variable refrigerant flow system has been described. However, the embodiment is also applicable to an air-conditioning apparatus including one indoor unit and one outdoor unit.
An embodiment is presented for the sake of example, and is not intended to limit the scope of the embodiment. Various modifications of the embodiment are conceivable, and various omissions, substitutions, and changes may be made without departing from the gist of the embodiment. These embodiments and modifications of the embodiments are also included in the scope and gist of the embodiment.
1: variable refrigerant flow system, 2: outdoor unit, 3a, 3b, 3c: indoor unit, 5: control unit, 5a: set concentration, 10: refrigerant pipe, 11: compressor, 12: outdoor heat exchanger, 13: outdoor fan, 14a, 14b, 14c: flow control valve, 21a, 21b, 21c: indoor heat exchanger, 22a, 22b, 22c: indoor fan, 30a, 30b, 30c: control unit, 31: refrigerant leakage sensor, 32a, 32b, 32c: warning unit
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2019/014638 | 4/2/2019 | WO |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2020/202465 | 10/8/2020 | WO | A |
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| Number | Date | Country | |
|---|---|---|---|
| 20220120485 A1 | Apr 2022 | US |
