GB2554582A

GB2554582A - Refrigerant leak detection device

Info

Publication number: GB2554582A
Application number: GB1717743.7A
Authority: GB
Inventors: Nasu Motoshi; Inoue Takuya
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2015-06-30
Filing date: 2015-06-30
Publication date: 2018-04-04
Also published as: JPWO2017002216A1; WO2017002216A1; GB201717743D0

Abstract

Provided is a highly reliable refrigerant leak detection device. The refrigerant leak detection device comprises: a plurality of detection circuits that detect outputs from a refrigerant sensor; and a control means that, on the basis of the outputs from the plurality of detection circuits, determines the presence of refrigerant leaks and determines the presence of errors in the plurality of detection circuits.

Description

(54) Title of the Invention: Refrigerant leak detection device Abstract Title: Refrigerant leak detection device (57) Provided is a highly reliable refrigerant leak detection device. The refrigerant leak detection device comprises: a plurality of detection circuits that detect outputs from a refrigerant sensor; and a control means that, on the basis of the outputs from the plurality of detection circuits, determines the presence of refrigerant leaks and determines the presence of errors in the plurality of detection circuits.

[010]

31.. . INDOOR UNIT

52a, 52b... REFRIGERANT SENSOR

72.. . ALARM

81.. . SHUTOFF VALVE

91.. . VENTILATION DEVICE

621a, 621b... DETECTION CIRCUIT

622.. . CONTROL MEANS

623.. . DRIVE CIRCUIT

624.. . POWER SUPPLY CIRCUIT

625.. . STORAGE MEANS

626.. . COMMUNICATIONS MEANS

627, 628, 629... SIGNAL OUTPUT MEANS AC... AC POWER SUPPLY σ>

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END

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DETECTIONS

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500 60 60 60

DESCRIPTION

Title of Invention

REFRIGERANT LEAKAGE DETECTION DEVICE

Technical Field [0001]

The present invention relates to a refrigerant leakage detection device configured to detect a leakage of refrigerant in a cooling-heating apparatus.

Background Art [0002]

A refrigerant leakage detection device is known to be provided in an airconditioning apparatus, a refrigerating apparatus, or other cooling-heating apparatus to detect a leakage of refrigerant from the cooling-heating apparatus. For example, in Patent Literature 1, it is disclosed that whether or not refrigerant has leaked is determined from a refrigerant concentration detected by a sensor. In Patent Literature 1, it is disclosed that, when it is determined that the refrigerant has leaked, a warning sound is issued from a warning buzzer, a cutoff valve is closed to cut off the flow of the refrigerant, and a ventilation fan is turned on to lower the refrigerant concentration in the room.

Citation List

Patent Literature [0003]

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2012-193884

Summary of Invention Technical Problem [0004]

The function of detecting a refrigerant leakage is an important function for safety. However, a leakage of refrigerant cannot be detected when a refrigerant leakage detection device or a refrigerant sensor is out of order.

[0005]

The present invention has been made to solve the problem described above, and an object of the present invention is therefore to provide a refrigerant leakage detection device high in reliability.

Solution to Problem [0006]

According to one embodiment of the present invention, there is provided a refrigerant leakage detection device including a plurality of detection circuits configured to detect output of at least one refrigerant sensor, and a control unit configured to determine whether or not refrigerant has leaked and whether or not an abnormality has occurred in the plurality of detection circuits on the basis of output from the plurality of detection circuits.

Advantageous Effects of Invention [0007]

In the refrigerant leakage detection device of one embodiment of the present invention, whether or not refrigerant has leaked and whether or not an abnormality has occurred in the plurality of detection circuits are determined on the basis of the output from the plurality of detection circuits, thereby enabling refrigerant leakage determination to be executed even when an abnormality has occurred in one of the plurality of detection circuits. In addition, the detection circuit in which an abnormality has occurred can be identified, thereby improving reliability.

Brief Description of Drawings [0008] [Fig. 1] Fig. 1 is a schematic block diagram of an air-conditioning system in

Embodiment 1 of the present invention.

[Fig. 2] Fig. 2 is a diagram for illustrating the internal configuration of a refrigerant leakage detection device according to Embodiment 1 and devices connected to the refrigerant leakage detection device.

[Fig. 3] Fig. 3 is a flow chart for illustrating the flow of refrigerant leakage detection processing in Embodiment 1.

[Fig. 4] Fig. 4 is an example of a layout map displayed on a centralized controller in Embodiment 1.

[Fig. 5] Fig. 5 is a diagram for illustrating devices that are placed in a residential room in a modification example of Embodiment 1.

[Fig. 6] Fig. 6 is a schematic block diagram of an air-conditioning system in Embodiment 2 of the present invention.

[Fig. 7] Fig. 7 is a diagram for illustrating the internal configuration of a refrigerant leakage detection device according to Embodiment 3 of the present invention and devices connected to the refrigerant leakage detection device.

[Fig. 8] Fig. 8 is a flow chart for illustrating a processing flow in an inspection mode of Embodiment 3.

[Fig. 9] Fig. 9 is a schematic side view of a refrigerant sensor and the refrigerant leakage detection device that are housed inside an indoor unit in Embodiment 3.

[Fig. 10] Fig. 10 is a diagram for illustrating the internal configuration of a refrigerant leakage detection device according to Embodiment 4 of the present invention and devices connected to the refrigerant leakage detection device.

[Fig. 11] Fig. 11 is a graph for showing transitions of output values of two refrigerant sensors in Embodiment 4.

[Fig. 12] Fig. 12 is a diagram for illustrating the internal configuration of a refrigerant leakage detection device according to Embodiment 5 of the present invention and devices connected to the refrigerant leakage detection device.

[Fig. 13] Fig. 13 is a diagram for illustrating the internal configuration of a refrigerant leakage detection device according to Embodiment 6 of the present invention and devices connected to the refrigerant leakage detection device.

[Fig. 14] Fig. 14 is a diagram for illustrating the internal configuration of a refrigerant leakage detection device according to Embodiment 7 of the present invention and devices connected to the refrigerant leakage detection device.

[Fig. 15] Fig. 15 is a schematic diagram of a modification example in which contacts of a plurality of refrigerant leakage detection devices are connected in series.

Description of Embodiments [0009]

Refrigerant leakage detection systems according to embodiments of the present invention are described in detail below with reference to the drawings. The following description deals with a refrigerant leakage detection system configured to detect a leakage of refrigerant in an air-conditioning system, which is given as an example of a cooling-heating system. Throughout the drawings of the embodiments, the same components are denoted by the same reference signs.

[0010]

Embodiment 1

Fig. 1 is a schematic block diagram of an air-conditioning system 10 in Embodiment 1 of the present invention. The air-conditioning system 10 of Embodiment 1 is configured to cool and heat the interior of a building 100 by vapor compression refrigeration cycle operation. The air-conditioning system 10 includes, as illustrated in Fig. 1, an outdoor unit 1 installed outside the building 100, a flow dividing controller 2 and a plurality of indoor units 31, 32, and 33 that are installed inside the building 100. In Fig. 1, solid lines that connect the components to one another represent refrigerant pipes and broken lines that connect the components to one another represent communication lines.

[0011]

The outdoor unit 1 is configured to supply cooling energy or heating energy to the interior of the building 100, and is installed outside the building 100. The outdoor unit 1 makes up a part of a refrigerant circuit, and includes a compressor 11, an outdoor heat exchanger (not shown), a four-way valve (not shown), an expansion valve (not shown), a fan 12 configured to supply air to the outdoor heat exchanger, and a controller 13. The operation capacity of the compressor 11 and the rotation frequency of the fan 12 are controlled by the controller 13. The controller 13 is communicably connected to the flow dividing controller 2, a controller (not shown) each included in the indoor units 31 to 33, and a centralized controller 40.

[0012]

The flow dividing controller 2 is interposed between the outdoor unit 1 and the indoor units 31 to 33 to perform flow dividing control on the flow of refrigerant to the indoor units 31 to 33. The flow dividing controller 2 is placed in, for example, the ceiling space of a monitor room 101 in the building 100.

[0013]

The indoor units 31 to 33 make up the refrigerant circuit together with the outdoor unit 1, and each include an indoor heat exchanger (not shown) and a fan (not shown) configured to supply air to the indoor heat exchanger. The indoor unit 31 is installed to be embedded in the ceiling of a residential room 102, and cools and heats the residential room 102. The indoor unit 32 is installed to be embedded in the ceiling of a residential room 103, and cools and heats the residential room 103. The indoor unit 33 is installed on the floor of the residential room 103, and cools and heats the residential room 103 along with the indoor unit 32.

[0014]

The indoor units 31,32, and 33 include remote controllers 41,42, and 43, respectively. The activation, deactivation, operation mode, set temperature, and other settings of the indoor units 31 to 33 can be controlled by operating the remote controllers 41 to 43. The centralized controller 40 configured to perform overall control of the air-conditioning system 10 is placed in the monitor room 101. The centralized controller 40 communicates with the flow dividing controller 2 and the controllers (not shown) of the indoor units 31 to 33 via the outdoor unit 1 to obtain the running states and other types of information of the flow dividing controller 2 and the indoor units 31 to 33.

[0015]

The refrigerant leakage detection system in the air-conditioning system 10 of Embodiment 1 is described next. A plurality of refrigerant sensors 51,52, 53, and 54 configured to detect refrigerant are placed in the building 100 as illustrated in Fig. 1. The refrigerant sensors 51 to 54 are, for example, semiconductor gas detection sensors, and detect a gas that is the same as, or equivalent to, a refrigerant used in the refrigerant circuit of the air-conditioning system 10. The refrigerant sensor 51 is incorporated in the flow dividing controller 2 and is placed, for example, at a pipe junction inside around a product. The refrigerant sensor 52 is installed on the floor of or on a wall close to the floor of the residential room 102. The refrigerant sensor 53 is incorporated in the indoor unit 32 of the residential room 103 and is placed, for example, close to the indoor heat exchanger. The refrigerant sensor 54 is installed on the floor of, or on a wall close to the floor of, the residential room 103. The refrigerant sensors 51 to 54 may be detachably installed. In this manner, the refrigerant sensors 51 to 54 can be replaced in the event of failure or deterioration in responsiveness due to long-term use.

[0016]

Detection signals from the refrigerant sensors 51, 52, 53, and 54 are output to refrigerant leakage detection devices 61,62, 63, and 64, respectively. The refrigerant leakage detection devices 61 to 64 are configured to determine whether or not refrigerant has leaked on the basis of the detection signals from the refrigerant sensors 51 to 54 and, when it is determined that refrigerant has leaked, activate safety devices. The refrigerant leakage detection device 61 is placed in the monitor room 101 to determine whether or not refrigerant has leaked from the flow dividing controller 2 on the basis of the detection signal from the refrigerant sensor 51. The refrigerant leakage detection device 62 is placed in the residential room 102 to determine whether or not refrigerant has leaked from the indoor unit 31 on the basis of the detection signal from the refrigerant sensor 52. The refrigerant leakage detection device 63 is placed in the residential room 103 to determine whether or not refrigerant has leaked from the indoor unit 32 on the basis of the detection signal from the refrigerant sensor 53. The refrigerant leakage detection device 64 is placed in the residential room 103 to determine whether or not refrigerant has leaked from the indoor unit 33 on the basis of the detection signal from the refrigerant sensor 54.

The refrigerant leakage detection devices 61 to 64 may be provided independently of the flow dividing controller 2 and the indoor units 31 to 33, or may be incorporated in the flow dividing controller 2 and the indoor units 31 to 33.

[0017]

Alarms 71, 72, and 73 configured to inform users of a leakage of refrigerant are installed in the monitor room 101 and the residential rooms 102 and 103, respectively. The alarm 71 is installed in the monitor room 101 to issue a warning sound when a leakage of refrigerant is detected by the refrigerant leakage detection device 61.

The alarm 72 is installed in the residential room 102 to issue a warning sound when a leakage of refrigerant is detected by the refrigerant leakage detection device 62.

The alarm 73 is installed in the residential room 103 to issue a warning sound when a leakage of refrigerant is detected by the refrigerant leakage detection device 63 or 64. The alarm 73 may be set such that a different warning sound is issued for each refrigerant sensor that detects a leakage of refrigerant. Specifically, the alarm 73 may vary the pitch of a warning sound depending on which of the refrigerant sensor 53 and the refrigerant sensor 54 detects a leakage of refrigerant. This configuration enables a user to figure out from the pitch of the sound of the alarm 73 where the refrigerant leakage has occurred even when a plurality of refrigerant sensors are placed in the residential room 103. The alarms 71 to 73 may be each incorporated in a corresponding one of the refrigerant leakage detection devices 61 to 64.

[0018]

Cutoff valves 81,82, and 83 are placed as a safety device in refrigerant pipes that connect the flow dividing controller 2 to the indoor units 31, 32, and 33, respectively. The cutoff valve 81 is interposed between the flow dividing controller 2 and the indoor unit 31, and is closed when a leakage of refrigerant is detected by the refrigerant leakage detection device 62. The cutoff valve 82 is interposed between the flow dividing controller 2 and the indoor unit 32, and is closed when a leakage of refrigerant is detected by the refrigerant leakage detection device 63. The cutoff valve 83 is interposed between the flow dividing controller 2 and the indoor unit 33, and is closed when a leakage of refrigerant is detected by the refrigerant leakage detection device 64.

[0019]

Ventilation devices 90, 91, and 92 are installed as another safety device in the monitor room 101 and the residential rooms 102 and 103, respectively. The ventilation devices 90 to 92 are, for example, propeller fans driven by fan motors (not shown). The ventilation device 90 is installed on a wall between the monitor room 101 and the residential room 102, and is activated when a leakage of refrigerant is detected by the refrigerant leakage detection device 61 to exhaust the refrigerant in the monitor room 101. The ventilation device 90 may instead be placed on a wall of the monitor room 101 that faces the outside to exhaust the refrigerant in the monitor room 101 to the outside. The ventilation device 91 is installed on a wall of the residential room 102, and is activated when a leakage of refrigerant is detected by the refrigerant leakage detection device 62 to exhaust the refrigerant in the residential room 102 to the outside. The ventilation device 92 is installed on a wall of the residential room 103, and is activated when a leakage of refrigerant is detected by the refrigerant leakage detection device 63 or 64 to exhaust the refrigerant in the residential room 103 to the outside.

[0020]

Fig. 2 is a diagram for illustrating the internal configuration of the refrigerant leakage detection device 62 and devices connected to the refrigerant leakage detection device 62. The internal configurations of the refrigerant leakage detection devices 61,63, and 64 are substantially the same as the internal configuration of the refrigerant leakage detection device 62, which is described here as a representative of the rest. The refrigerant leakage detection device 62 includes, as illustrated in Fig. 2, a detection circuit 621 configured to detect output from the refrigerant sensor 52, a control unit 622 configured to perform overall control of the refrigerant leakage detection device 62, a drive circuit 623 configured to drive safety devices, a power circuit 624 configured to supply power to the components of the refrigerant leakage detection device 62, a storage unit 625, a communication unit 626 configured to communicate with the indoor unit 31, and signal output units 627, 628, and 629 connected to the safety devices.

[0021]

The detection circuit 621 is configured to detect the detection signal from the refrigerant sensor 52, convert an alternating current into a direct current on the detection signal, and output the signal to the control unit 622 as an output value that is a direct current voltage value or other value. The control unit 622 is configured to control the components of the refrigerant leakage detection device 62 and includes, for example, a microcomputer. The detection circuit 621 may be included in the control unit 622 in another embodiment. The drive circuit 623 is configured to drive the signal output units 627, 628, and 629 in response to a control signal from the control unit 622. The alarm 72 is connected to the signal output unit 627. The cutoff valve 81 is connected to the signal output unit 628. The ventilation device 91 is connected to the signal output unit 629. The refrigerant leakage detection device 62 may further include signal output units that are connected to devices other than the alarm 72, the cutoff valve 81, and the ventilation device 91.

[0022]

The power circuit 624 is configured to convert, for example, power from an alternating current source AC that is a commercial power source into direct current power of DC I 2 V, DC 5 V, and other voltages, and supply the converted power to the drive circuit 623 and the control unit 622. In Embodiment 1, the refrigerant leakage detection device 62 is supplied with power independently of the indoor unit 31 to be active all the time. In another embodiment, the refrigerant leakage detection device 62 may instead be supplied with power from a power circuit of the indoor unit 3 to be activated in conjunction with the indoor unit 31. The storage unit 625 includes, for example, a semiconductor memory, and is configured to store various types of data and programs that are used to control the refrigerant leakage detection device 62.

The communication unit 626 is configured to transmit and receive data to and from the controller (not shown) of the indoor unit 31 through wired or wireless communication. The communication unit 626 is communicable with the remote controller 41 and the centralized controller 40 via the indoor unit 31. Alternatively, the communication unit 626 may directly communicate with the centralized controller 40 or the remote controller 41.

[0023]

Fig. 3 is a flow chart for illustrating the flow of refrigerant leakage detection processing of the refrigerant leakage detection device 62. In this processing, the detection signal from the refrigerant sensor 52 is first obtained by the detection circuit 621, and is converted into an output value to be output to the control unit 622 (S1). The control unit 622 next compares the output value to a set value that serves as a reference for determining refrigerant leakage (S2). The set value is a value defined in standards of the industry or other reference, and is stored in the storage unit 625. The set value may instead be a variable value that is adjusted to the situation of a site where the refrigerant leakage detection device 62 is installed. Ill-advised loosening of the sensitivity of refrigerant leakage detection is prevented by employing a mechanism that keeps a general user from adjusting the set value. When the output value is less than the set value (S2, NO), it is determined that refrigerant has not leaked, and the processing returns to Step S1.

[0024]

When the output value is equal to or more than the set value (S2, YES), on the other hand, it is determined that a leakage of refrigerant has occurred, and a leakage signal is transmitted from the control unit 622 to the drive circuit 623. The drive circuit 623 receives the leakage signal and drives the signal output unit 627 to activate the alarm 72 (S3). This operation causes the alarm 72 to issue a warning sound. The drive circuit 623 also drives the signal output units 628 and 629 to activate the other safety devices (S4). Specifically, the cutoff valve 81 connected to the signal output unit 628 is closed, and the ventilation device 91 connected to the signal output unit 629 is driven. In the case of the refrigerant leakage detection device 61 to which no cutoff valve is connected, a signal that instructs the outdoor unit 1 to stop the compressor 11 is transmitted instead of activating a cutoff valve.

This operation stops the flow of refrigerant to the flow dividing controller 2.

[0025]

The control unit 622 then transmits a signal that notifies the occurrence of a leakage of refrigerant to the indoor unit 31 via the communication unit 626 (S5). The notification signal is transmitted from the indoor unit 31 to the centralized controller 40 via the outdoor unit 1. The control unit 622 also stores, in the storage unit 625, a time and date at which the leakage of refrigerant has occurred and an output value of the refrigerant sensor 52 at that time (S6).

[0026]

In this manner, when a leakage of refrigerant is detected by the refrigerant sensor 52, the alarm 72 issues a warning sound to inform a user of the refrigerant leakage, and the cutoff valve 81 and the ventilation device 91 are activated to stop the flow of refrigerant to the indoor unit 31 and exhaust the refrigerant leaked into the residential room 102 to the outside of the room.

[0027]

The transmission of the signal notifying the detection of a refrigerant leakage from the refrigerant leakage detection device 62 to the centralized controller 40 via the indoor unit 31 enables the centralized controller 40 to find out the occurrence of refrigerant leakage. In the air-conditioning system 10 of Embodiment 1, unique addresses are set not only to the outdoor unit 1, the flow dividing controller 2, and the indoor units 31 to 33, but also to the refrigerant sensors 51 to 54, the refrigerant leakage detection devices 61 to 64, the alarms 71 to 73, the cutoff valves 81 to 83, and the ventilation devices 90 to 92. The centralized controller 40 can keep track of the states of the refrigerant sensors 51 to 54, the refrigerant leakage detection devices 61 to 64, the alarms 71 to 73, the cutoff valves 81 to 83, and the ventilation devices 90 to 92, as well as the running states of the indoor units 31 to 33, and the states and the running states can be displayed in a layout map.

[0028]

Fig. 4 is an example of a layout map displayed on the centralized controller 40. The centralized controller 40 includes a display unit 410, which includes a liquid crystal display or a similar display. The display unit 410 is configured to display the layout of the building 100, and icons representing the refrigerant leakage detection devices 61 to 64, the refrigerant sensors 51 to 54, the alarms 71 to 73, the cutoff valves 81 to 83, and the ventilation devices 90 to 92, which are placed in the corresponding rooms. The centralized controller 40 receives a signal that notifies the detection of refrigerant leakage, and then displays icons representing a refrigerant sensor from which the refrigerant leakage has been detected, and an alarm, a cutoff valve, and a ventilation device that are activated due to the refrigerant leakage, in a different color, or flashes the icons. The display unit 410 thus recognizably displays an area where refrigerant has leaked. The area of refrigerant leakage can be identified as a result, which is helpful in evacuation guidance and speedy repair work at the time of the refrigerant leakage. The display unit 410 only needs to display at least one of icons representing ones in a corresponding room from the refrigerant leakage detection devices 61 to 64, the refrigerant sensors 51 to 54, the alarms 71 to 73, the cutoff valves 81 to 83, and the ventilation devices 90 to 92.

[0029]

As described above, according to Embodiment 1, the site, scale, or other aspect of a refrigerant leakage can be found out quickly even when a plurality of refrigerant sensors 51 to 54 and a plurality of refrigerant leakage detection devices 61 to 64 are placed in the building 100. This configuration helps in guiding evacuation appropriately and improves safety.

[0030]

While one refrigerant sensor is connected to one refrigerant leakage detection device in Embodiment 1, the present invention is not limited to this configuration, and a plurality of refrigerant sensors may be connected to one refrigerant leakage detection device. Fig. 5 is a diagram for illustrating devices that are placed in the residential room 102 in a modification example of Embodiment 1. In the example of Fig. 5, a refrigerant sensor 55 incorporated in the indoor unit 31 is provided in addition to the refrigerant sensor 52, which is placed close to the floor of the residential room 102. The refrigerant leakage detection device 62 receives a detection signal from the refrigerant sensor 52 and a detection signal from the refrigerant sensor 55 separately, and compares each received detection signal to the set value. When even one of the received detection signals is equal to or more than the set value, the refrigerant leakage detection device 62 determines that a leakage of refrigerant has occurred.

[0031]

When a refrigerant sensor is placed in the ceiling and on the floor each as in the example of Fig. 5, the speed and amount of refrigerant leakage can be estimated by calculating a difference between the time in which one refrigerant sensor is active and the time in which the other refrigerant sensor is active. For example, when the difference in active time between the refrigerant sensor 52 and the refrigerant sensor 55 is small, refrigerant may have leaked at high speed and in large amount. In this case, it is determined that immediate evacuation is necessary, and a warning is issued from the alarm 72 to advise immediate evacuation. When the difference in active time between the refrigerant sensor 52 and the refrigerant sensor 55 is large, or when the detection signal from only one of the refrigerant sensors 52 and 55 is equal to or more than the set value, refrigerant may have leaked at low speed and in small amount. In this case, it is determined that immediate evacuation is not necessary, and a visual or audio instruction may be given for maintenance work instead of issuing a warning sound from the alarm 72. The sound and volume of the alarm 72 may be varied corresponding to the speed and amount of the refrigerant leakage.

[0032]

Embodiment 2

Embodiment 2 of the present invention is described next. Embodiment 2 differs from Embodiment 1 in that an air-conditioning system 10A includes a heat source apparatus 1A in place of the outdoor unit 1. Fig. 6 is a schematic block diagram of the air-conditioning system 10A in Embodiment 2. The heat source apparatus 1A is placed in a machine room 104 inside the building 100 as illustrated in Fig. 6. The heat source apparatus 1A is configured to supply cooling energy or heating energy to the interior of the building 100, and includes the compressor 11, a water heat exchanger 14, a four-way valve (not shown), an expansion valve (not shown), and the controller 13. A cooling tower 15 and a water pump 16, which are used to supply water to the water heat exchanger 14, are placed outside the machine room 104.

[0033]

A refrigerant sensor 56, a refrigerant leakage detection device 65, an alarm 74, and a ventilation device 93 are provided in the machine room 104 to detect a leakage of refrigerant from the heat source apparatus 1 A. The configurations of the refrigerant sensor 56, the refrigerant leakage detection device 65, the alarm 74, and the ventilation device 93 are the same as the configurations of the refrigerant sensors 51 to 54, the refrigerant leakage detection devices 61 to 64, the alarms 71 to 73, and the ventilation devices 90 to 92 in Embodiment 1. The refrigerant leakage detection device 65 executes refrigerant leakage detection processing similar to the one of Embodiment 1 illustrated in Fig. 3. In the refrigerant leakage detection device 65, however, the ventilation device 93 is activated and the running of the compressor 11 is stopped in Step S4 of Fig. 3.

[0034]

Addresses are set to the refrigerant sensor 56, the refrigerant leakage detection device 65, the alarm 74, and the ventilation device 93 as well. The states of the refrigerant sensor 56, the refrigerant leakage detection device 65, the alarm 74, and the ventilation device 93 are displayed in the layout map of the centralized controller 40.

[0035]

As described above, according to Embodiment 2, when the heat source apparatus 1A is included inside the building 100, the centralized controller 40 can quickly find out a leakage of refrigerant in the heat source apparatus 1 A.

[0036]

Embodiment 3

Embodiment 3 of the present invention is described next. Embodiment 3 differs from Embodiment 1 in that the control units of the refrigerant leakage detection devices execute a normal mode in which refrigerant leakage detection is conducted in a normal state, and an inspection mode in which whether or not the refrigerant leakage detection system operates normally is checked. The following description takes as an example a case in which a refrigerant leakage detection device 62A according to Embodiment 3 and the refrigerant sensor 52, the alarm 72, the cutoff valve 81, and the ventilation device 91 that are connected to the refrigerant leakage detection device 62A are inspected.

[0037]

Fig. 7 is a diagram for illustrating the internal configuration of the refrigerant leakage detection device 62A according to Embodiment 3 and devices connected to the refrigerant leakage detection device 62A. As illustrated in Fig. 7, the refrigerant leakage detection device 62A includes a display unit 631 and an operation unit 632 in addition to the detection circuit 621, the control unit 622, the drive circuit 623, the power circuit 624, the storage unit 625, the communication unit 626, and the signal output units 627 to 629, which are the same as those in Embodiment 1. The display unit 631 includes, for example, an LED. The operation unit 632 includes, for example, a slide switch.

[0038]

Detection signals from a flow rate sensor 810 and of a wind velocity sensor 910 are input to the detection circuit 621 in Embodiment 3 in addition to the detection signal from the refrigerant sensor 52. The flow rate sensor 810 is arranged on the downstream side of the cutoff valve 81, and is configured to detect the flow rate of refrigerant on the downstream side of the cutoff valve 81. The wind velocity sensor 910 is mounted to the ventilation device 91, and is configured to detect the wind velocity of the ventilation device 91.

[0039]

The control unit 622 executes a normal mode in which refrigerant leakage detection is conducted in a normal state, and an inspection mode in which whether or not the refrigerant leakage detection system operates normally is checked. In the normal mode, the refrigerant leakage detection processing (Fig. 3) of Embodiment 1 is executed. The control unit 622 includes, as function units used in the inspection mode, a mode switching unit 21, an inspection instruction unit 22, a determination unit 23, a display control unit 24, and a clock unit 25, which are illustrated in Fig. 7. The function units are implemented on software by, for example, executing a program with the use of the control unit 622.

[0040]

The mode switching unit 21 is configured to switch the normal mode and the inspection mode in response to operation performed on the operation unit 632. Alternatively, the mode switching unit 21 may switch the normal mode and the inspection mode on the basis of an operation signal that is received from the centralized controller 40 or the remote controller 41 via the communication unit 626. When a switch to the inspection mode is made, the mode switching unit 21 transmits a signal that instructs the indoor unit 31 to stop the fan 310 to the indoor unit 31 via the communication unit 626.

[0041]

The inspection instruction unit 22 is configured to transmit, when a switch to the inspection mode is made, an inspection signal that instructs inspection to the drive circuit 623. The determination unit 23 is configured to determine from an output value of the detection circuit 621 whether or not the components of the refrigerant leakage detection device 62A operate normally. The result of the inspection that is issued by the determination unit 23 is stored in the storage unit 625 along with the time and date of inspection. The display control unit 24 is configured to control the display unit 631 so that a prompt for inspection and an indicator indicating that the current mode is the inspection mode are displayed. The clock unit 25 is configured to measure time that has elapsed from a switch to the inspection mode.

[0042]

The refrigerant leakage detection device 62A and the refrigerant sensor 52, the alarm 72, the cutoff valve 81, and the ventilation device 91 that are connected to the refrigerant leakage detection device 62A are inspected periodically. For example, warning issuance inspection of the alarm 72 is conducted once a month or more, and inspection of the other devices is conducted once a year or more. The display control unit 24 in Embodiment 3 displays a prompt for inspection on the display unit 631 when an inspection time limit approaches. The timing of displaying a prompt for inspection is variable and can be set to, for example, two weeks before the legal inspection time limit, to thereby remind the user to arrange for an inspector. The display control unit 24 may instruct, via the communication unit 626, the remote controller 41 or the centralized controller 40 to display a prompt for inspection, or may prompt inspection by e-mail over an Internet line. When a maintenance and inspection person is set as the destination of the e-mail, an order for inspection is placed automatically by sending the e-mail.

[0043]

Fig. 8 is a flow chart for illustrating a processing flow in the inspection mode. This processing is started when a switch to the inspection mode is made by the mode switching unit 21. In this processing, the centralized controller 40 or the remote controller 41 first displays an indicator indicating that the current mode is the inspection mode in accordance with instruction from the display control unit 24 (S21). Specifically, inspecting may be displayed on the remote controller 41 or the centralized controller 40, or an LED that indicates the inspection mode may be lit.

The fact that the inspection mode is being executed can be notified to the outside in this manner. When the centralized controller 40 or the remote controller 41 is not connected, the indicator of the inspection mode may be displayed on a display unit of the indoor unit 31 or other devices, or may be displayed on the display unit 631 of the refrigerant leakage detection device 62A. Measures other than display, such as sound, may be used to inform that the current mode is the inspection mode.

[0044]

Next, the fan 310 of the indoor unit 31 is stopped in accordance with instruction from the mode switching unit 21 (S22). It is difficult to detect refrigerant when the fan 310 of the indoor unit 31 operates because the fan 310 disperses the refrigerant and lowers the concentration of refrigerant. Refrigerant detection is facilitated in the inspection mode by stopping the fan 310.

[0045]

The refrigerant leakage detection device 62A, the refrigerant sensor 52, the alarm 72, the cutoff valve 81, and the ventilation device 91 are then inspected (S23). The inspection may be conducted for each of the devices individually, or all of the devices may be inspected in conjunction with one another. For example, when many refrigerant sensors are connected to the refrigerant leakage detection device 62A, the inspection count can be reduced by separating the alarm 72, the cutoff valve 81, and the ventilation device 91 from the rest and inspecting the separated devices individually. In addition, the cutoff valve 81 does not have to be activated each time a refrigerant sensor is inspected, and hence the indoor unit 31 can be kept running. The following description deals with a case where the refrigerant leakage detection device 62A, the refrigerant sensor 52, the alarm 72, the cutoff valve 81, and the ventilation device 91 are inspected individually.

[0046] (Inspection of the Refrigerant Sensor 52)

In the inspection of the refrigerant sensor 52, refrigerant is blown onto the refrigerant sensor 52 and, when the determination unit 23 determines that the output value of the refrigerant sensor 52 is equal to or more than a reference value, it is determined that the refrigerant sensor 52 and the refrigerant leakage detection device 62A operate normally. The output value of the refrigerant sensor 52 may be displayed on the display unit 631, the remote controller 41, the centralized controller 40, or other devices to determine whether or not the output value is a proper value. The refrigerant blown onto the refrigerant sensor 52 is the same as or equivalent to the refrigerant that is used in the refrigerant circuit of the air-conditioning system 10. However, a refrigerant that has a low concentration may be used to check the operation of the refrigerant sensor 52 in the inspection mode.

[0047]

When a refrigerant sensor to be inspected is incorporated in the indoor unit 32 as is the case for the refrigerant sensor 53 illustrated in Fig. 1, an exterior panel of the indoor unit 32 needs to be removed with the use of a tool or an instrument to blow refrigerant onto the refrigerant sensor 53, which is very laborious. An opening may therefore be formed in a casing (for example, the exterior panel) of the indoor unit 32 to blow gas onto the refrigerant sensor 53 through the opening. Fig. 9 is a schematic side view of the refrigerant sensor 53 and the refrigerant leakage detection device 63 that are housed inside the indoor unit 32. In the example of Fig. 9, a casing 321 of the indoor unit 32 serves as the casing of the refrigerant leakage detection device 63 and the refrigerant sensor 53. The indoor unit 32 is placed with the casing 321 embedded in the ceiling. An opening 322 is formed in a place in the casing 321 that faces the refrigerant sensor 53. The opening 322 is a small-sized hole that is open enough to insert a nozzle through which refrigerant gas is blown.

The opening 322 is normally closed and can be opened without a tool during inspection. In this manner, the inspection can be conducted without removing the exterior panel of the indoor unit 32 when the refrigerant sensor 53 is incorporated in the indoor unit 32, and work efficiency is improved.

[0048] (Inspection of Alarm 72)

In the inspection of the alarm 72, an inspection signal is transmitted from the inspection instruction unit 22 to the drive circuit 623, and whether or not the alarm 72 and the refrigerant leakage detection device 62A operate normally is checked on the basis of the warning issuance of the alarm 72. Specifically, the drive circuit 623 receives the inspection signal and drives the signal output unit 627 to activate the alarm 72. When the alarm 72 issues a warning sound, it is determined that the alarm 72 operates normally. Alternatively, a microphone may be mounted to the alarm 72 and connected to the refrigerant leakage detection device 62A so that the operation of the alarm 72 is checked by the determination unit 23 on the basis of an output value of the microphone. The alarm 72 may also be provided with an activation switch to check whether or not operation of the activation switch causes the alarm 72 to issue a warning. The alarm 72 in this case can be inspected independently of even the refrigerant leakage detection device 62A.

[0049]

The drive circuit 623 may activate the alarm 72 to issue a warning in the inspection mode at a sound volume lower than in the normal mode. This configuration prevents the alarm 72 from issuing a warning at a sound volume higher than necessary during inspection.

[0050] (Inspection of Cutoff Valve 81)

In the inspection of the cutoff valve 81, an inspection signal is transmitted from the inspection instruction unit 22 to the drive circuit 623, and whether or not the cutoff valve 81 and the refrigerant leakage detection device 62A operate normally is checked on the basis of an output value of the flow rate sensor 810. Specifically, the drive circuit 623 receives the inspection signal and drives the signal output unit 628 to activate the cutoff valve 81. When the cutoff valve 81 is closed normally, the flow rate detected by the flow rate sensor 810 drops. The determination unit 23 determines whether the cutoff valve 81 operates normally on the basis of the output value that is output from the flow rate sensor 810 when the cutoff valve 81 is opened or closed.

[0051]

As another embodiment, a pressure sensor may be arranged on the downstream side of the cutoff valve 81 in place of the flow rate sensor 810 to check the operation of the cutoff valve 81 on the basis of a change in pressure. Flow rate sensors or pressure sensors may be arranged on the upstream and downstream of the cutoff valve 81 to check the operation of the cutoff valve 81 on the basis of a difference in flow rate or pressure between the upstream and downstream of the cutoff valve 81.

[0052] (Inspection of Ventilation Device 91)

In the inspection of the ventilation device 91, an inspection signal is transmitted from the inspection instruction unit 22 to the drive circuit 623, and whether or not the ventilation device 91 and the refrigerant leakage detection device 62A operate normally is checked on the basis of the output value of the wind velocity sensor 910. Specifically, the drive circuit 623 receives the inspection signal and drives the signal output unit 629 to activate the ventilation device 91. When the ventilation device 91 is activated normally, the wind velocity detected by the wind velocity sensor 910 rises. The determination unit 23 determines whether the ventilation device 91 operates normally on the basis of the output value of the wind velocity sensor 910.

[0053]

As another embodiment, whether or not the ventilation device 91 rotates may be checked visually after an inspection signal is transmitted from the inspection instruction unit 22 to the drive circuit 623. A flow rate sensor may be mounted to the ventilation device 91 in place of the wind velocity sensor 910 to check the operation of the ventilation device 91 from a change in flow rate.

[0054]

The methods of inspecting the devices are not limited to the ones described above, and various modifications can be made. Not all of the refrigerant sensor 52, the alarm 72, the cutoff valve 81, and the ventilation device 91 need to be inspected, and devices to be inspected may be selected from the refrigerant sensor 52, the alarm 72, the cutoff valve 81, and the ventilation device 91. When all of the devices are inspected in conjunction with one another, refrigerant is blown onto the refrigerant sensor 52, and whether the alarm 72, the cutoff valve 81, and the ventilation device 91 turn active may be checked when an output value of the refrigerant sensor 52 reaches a predetermined concentration.

[0055]

The result of the inspection that is issued by the determination unit 23 and the output values of the sensors may be displayed on the display unit 631, the remote controller 41, or the centralized controller 40.

[0056]

Whether or not the inspection mode is ended is determined next (S24). In this step, whether or not the inspection mode has been switched to the normal mode is determined on the basis of the operation performed on the operation unit 632, or on the centralized controller 40 or the remote controller 41. When the inspection mode is ended (S24, YES), the inspection date, or the time and date of inspection, and the inspection result are stored in the storage unit 625 (S26). The inspection result stored in this step is, for example, whether or not normal operation has been confirmed for the refrigerant sensor 52, the alarm 72, the cutoff valve 81, and the ventilation device 91, or output values of the refrigerant sensor 52, the flow rate sensor 810, the wind velocity sensor 910, and the microphone. The precision of sensing can be recorded as well by storing a concentration of the refrigerant gas that has been used in the inspection in association with an actual measured value of the refrigerant sensor 52.

[0057]

The time and date of inspection and the inspection result may be stored in an SD card (trademark) or other external memories in addition to the storage unit 625. Alternatively, the inspection result and the time and date of inspection may be transmitted via the communication unit 626 to the remote controller 41, the centralized controller 40, or other external devices. The time and date of inspection and the inspection result may be output as a form. A form may be output by providing the refrigerant leakage detection device 62A with a form outputting unit, or by transmitting via the communication unit 626 the time and date of inspection and the inspection result to an external device that has a form output function and instructing the external device to output the time and date of inspection and the inspection result as a form.

[0058]

When the inspection mode is not ended (S24, NO), on the other hand, whether or not an inspection period has passed is determined (S25). When the inspection period has not passed (S25, NO), the processing returns to Step S24. The inspection period is a length of time required to conduct inspection, and is set in advance to be stored in the storage unit 625. When the inspection period has passed (S25, YES), the processing proceeds to Step S26, and the time and date of inspection and the inspection result are stored in the storage unit 625 (S26). A failure to remember switching to the normal mode can be prevented by ending the inspection mode automatically at the elapse of a given length of time in this manner. At the time the inspection period expires, the return to the normal mode may be informed by display or sound. The inspection period may be extended to continue the inspection by prompting the user to input a length of time by which the inspection period is extended and receiving the input for extending the inspection period.

[0059]

The fan 310 of the indoor unit 31 is then activated (S27), the display of an indicator on the remote controller 41, the centralized controller 40, or the display unit 631 that indicates that the current mode is the inspection mode is turned off (S28), and the inspection mode is ended. At the same time as the display of an indicator indicating the inspection mode is turned off, the return to the normal mode may be informed by display or sound. This operation enables the inspector to recognize the return to the normal mode.

[0060]

The inspection mode may be ended in the middle of inspection of Step S23.

In this case, how far the inspection has progressed may be stored in the storage unit 625 so that, when the inspection mode is selected the next time, the inspection can be resumed from that point.

[0061]

As described above, according to Embodiment 3, an time and date of inspection and an inspection result in the inspection mode can be saved and displayed in the form of data, or can be output as a form. The fact that inspection has been reliably conducted and the specifics of the inspection can thus be confirmed.

[0062]

While inspection is conducted for one refrigerant sensor 52 in Embodiment 2, the present invention is not limited to this configuration. For example, the refrigerant sensors 51 to 54 in the air-conditioning system 10 may be removed, put in a container together, and blown with an inspection-use refrigerant to check the sensors' reaction to the refrigerant. This configuration makes the inspection work efficient when many refrigerant sensors are provided.

[0063]

The refrigerant sensor 52 may be calibrated on the basis of the output value of the refrigerant sensor 52. Specifically, the concentration of refrigerant blown onto the refrigerant sensor 52 and an actual measured value of the refrigerant sensor 52 are displayed on the remote controller 41, the centralized controller 40, or the display unit 631. The detection level of the refrigerant sensor 52 is then raised or dropped by operating the remote controller 41, the centralized controller 40, or the operation unit 632 while looking at the display. The refrigerant sensor 52 can be calibrated in this manner. The refrigerant sensor 52 may instead be calibrated by bringing a concentration meter that has separately been calibrated, and adjusting values through comparison. Another option is to connect two refrigerant sensors that are placed in the same location to the refrigerant leakage detection device 62A and compare output values of the two refrigerant sensors.

[0064]

A mechanism that causes a leakage of a small amount of refrigerant from the indoor unit 31 may be included to use the refrigerant leaked from the indoor unit 31 for the inspection of the refrigerant sensor 52 in the inspection mode. In this case, inspection can be conducted automatically without needing to blow refrigerant onto the refrigerant sensor 52.

[0065]

While the fan 310 of the indoor unit 31 is stopped in Step S22 of the inspection mode in Embodiment 2, the running of the indoor unit 31 may be stopped instead. Specifically, the flow of refrigerant to the indoor unit 31 may be stopped by closing the cutoff valve 81 in Step S22. The indoor unit 32 or 33 may be stopped in addition to the indoor unit 31. Alternatively, the outdoor unit 1, the flow dividing controller 2, and the indoor units 31 to 33, which belong to the same refrigerant system, may be stopped. When a plurality of outdoor units (heat source apparatus) form parts of a plurality of refrigerant systems, all refrigerant systems may be stopped completely. The inspector may be allowed to select how many units or systems are to be stopped. [0066]

Embodiment 4

Embodiment 4 of the present invention is described next. Embodiment 4 differs from Embodiment 1 in that refrigerant sensors and detection circuits are doubled in number. Fig. 10 is a diagram for illustrating the internal configuration of a refrigerant leakage detection device 62B according to Embodiment 4 and devices connected to the refrigerant leakage detection device 62B. As illustrated in Fig. 10, the refrigerant leakage detection device 62B according to Embodiment 4 includes two detection circuits 621a and 621b, to which refrigerant sensors 52a and 52b are connected respectively. The two detection circuits 621a and 621 b are circuits having the same specifications.

[0067]

The refrigerant sensors 52a and 52b are placed in the same location (for example, on the floor of or on a wall close to the floor of the residential room 102).

The refrigerant sensor 52a is an expensive, high-precision sensor, whereas the refrigerant sensor 52b is an inexpensive, low-precision sensor. The control unit 622 separately compares output values of the detection circuits 621a and 621 b to the set value, and determines that refrigerant has leaked when even one ofthe output values is equal to or more than the set value. By doubling refrigerant sensors and detection circuits in number in this manner, a leakage of refrigerant can be detected even when one of the refrigerant sensors or one of the detection circuits is in an abnormal state. [0068]

Fig. 11 is a graph for showing transitions of output values of the refrigerant sensors 52a and 52b. The axis of ordinate represents the sensor output value and the axis of abscissa represents time in Fig. 11. The output value of the refrigerant sensor 52a is represented by the solid line, and the output value of the refrigerant sensor 52b is represented by the broken line. When an abnormality occurs in the refrigerant sensor 52a or the detection circuit 621a, the output value is fixed or fluctuates only minutely. When the output value of the refrigerant sensor 52a is fixed or fluctuates only minutely whereas the output value of the refrigerant sensor 52b is fluctuating, it can be determined that an abnormality has occurred in the refrigerant sensor 52a or the detection circuit 621a.

[0069]

As described above, according to Embodiment 4, doubling refrigerant sensors and detection circuits in number ensures detection of a leakage of refrigerant even when one of the refrigerant sensors or one of the detection circuits is in an abnormal state. Reliability is improved as a result. In addition, which of the refrigerant sensors or which of the detection circuits is in the abnormal state can be determined by comparing output values of the two refrigerant sensors.

[0070]

Embodiment 5

Embodiment 5 of the present invention is described next. Embodiment 5 differs from Embodiment 4 in that detection circuits are doubled in number for one refrigerant sensor. Fig. 12 is a diagram for illustrating the internal configuration of a refrigerant leakage detection device 62C according to Embodiment 5 and devices connected to the refrigerant leakage detection device 62C. As illustrated in Fig. 12, the refrigerant leakage detection device 62C according to Embodiment 5 includes two detection circuits 621a and 621b associated with one refrigerant sensor 52.

[0071]

The control unit 622 separately compares output values of the detection circuits 621a and 621b to the set value, and determines that refrigerant has leaked when even one of the output values is equal to or more than the set value. By doubling detection circuits in number in this manner, a leakage of refrigerant can be detected even when one of the refrigerant sensor or one of the detection circuits is in an abnormal state. In addition, as in Embodiment 4, which of the detection circuits is in the abnormal state can be determined on the basis of fluctuations in the output values of the detection circuits 621a and 621b.

[0072]

As described above, according to Embodiment 5, doubling detection circuits in number ensures detection of a leakage of refrigerant even when one of the detection circuits is in an abnormal state. Reliability is improved as a result. The number of parts and cost can also be reduced by using one refrigerant sensor that relatively hardly has an abnormality.

[0073]

Embodiment 6

Embodiment 6 of the present invention is described next. Embodiment 6 differs from Embodiment 1 in that whether or not an abnormality occurs in a detection circuit is determined during normal operation. Fig. 13 is a diagram for illustrating the internal configuration of a refrigerant leakage detection device 62D according to Embodiment 6 and devices connected to the refrigerant leakage detection device 62D. As illustrated in Fig. 13, the refrigerant leakage detection device 62D according to Embodiment 6 additionally includes an input switching circuit 630. A detection signal from the refrigerant sensor 52 and a reference voltage (for example, 2.5 V) from the power circuit 624 are input to the input switching circuit 630. The input switching circuit 630 is configured to periodically switch the detection signal from the refrigerant sensor 52 and the reference voltage under control of the control unit

622, and output the detection signal or the reference voltage to the detection circuit 621.

[0074]

The control unit 622 monitors the output value of the detection circuit 621.

When the output value that is output by the detection circuit 621 when the reference voltage is input differs from the reference voltage, the control unit 622 determines that the detection circuit 621 is out of order. When determining that the detection circuit 621 is out of order, the control unit 622 transmits a failure signal to the drive circuit

623. The drive circuit 623 receives the failure signal, drives the signal output unit 628 to close the cutoff valve 81, and drives the signal output unit 627 to activate the alarm 72 and to issue a warning that informs of the failure.

[0075]

As described above, according to Embodiment 6, an abnormality in a detection circuit can be found quickly, which improves the reliability.

[0076]

Embodiment 7

Embodiment 7 of the present invention is described next. Embodiment 7 differs from Embodiment 6 in that the detection signal from the refrigerant sensor 52 and the reference voltage are each input as two parallel inputs, and in that input switching circuits and detection circuits are doubled in number. Fig. 14 is a diagram for illustrating the internal configuration of a refrigerant leakage detection device 62E according to Embodiment 7 and devices connected to the refrigerant leakage detection device 62E. As illustrated in Fig. 14, the refrigerant leakage detection device 62E according to Embodiment 7 includes the two detection circuits 621a and

621 b and two input switching circuits 630a and 630b. The detection signal from the refrigerant sensor 52 and the reference voltage (for example, 2.5 V) from the power circuit 624 are input to each of the input switching circuits 630a and 630b. The input switching circuits 630a and 630b are configured to periodically switch the detection signal from the refrigerant sensor 52 and the reference voltage under control of the control unit 622, and output the detection signal or the reference voltage to the detection circuits 621a and 621b, respectively. In Fig. 14, communication lines between the control unit 622 and the input switching circuits 630a and 630b are omitted.

[0077]

The control unit 622 monitors the output values of the detection circuits 621a and 621b. When the output value that is output by the detection circuit 621 a or 621 b when the reference voltage is input differs from the reference voltage, the control unit

622 determines that the detection circuit 621a or 621 b is out of order. When determining that the detection circuit 621a or 621 b is out of order, the control unit 622 transmits a failure signal to the drive circuit 623. The drive circuit 623 receives the failure signal, drives the signal output unit 628 to close the cutoff valve 81, and drives the signal output unit 627 to activate the alarm 72 and to issue a warning that informs of the failure.

[0078]

As described above, according to Embodiment 7, an abnormality in a detection circuit can be found quickly. In addition, doubling detection circuits in number ensures detection of a leakage of refrigerant even when one of the detection circuits is out of order, which improves the reliability even more.

[0079]

This concludes the description on embodiments of the present invention. However, the present invention is not limited to the configurations of the embodiments described above, and various modifications can be made to the embodiments, or the embodiments can be combined with one another, within the technical concept of the present invention. For example, whether or not refrigerant has leaked is determined in Embodiment 1 and Embodiment 2 on the basis of the output value of the refrigerant sensor 52, which directly detects refrigerant gas. Instead of the output value of the refrigerant sensor 52, an output value of a pressure sensor, a temperature sensor, or a similar sensor may be used to determine whether or not refrigerant has leaked. Specifically, the control unit 622 may use a known method to determine whether or not refrigerant has leaked on the basis of a refrigerant temperature detected by a temperature sensor or a refrigerant pressure detected by a pressure sensor.

[0080]

The refrigerant leakage detection device according to Embodiment 3 to Embodiment 7 may be used in a room air-conditioning apparatus, a refrigerator, or other stand-alone cooling-heating apparatus, as well as in the air-conditioning system 10 or other cooling-heating systems. While refrigerant sensors or detection circuits are doubled in number in Embodiment 4, Embodiment 5, and Embodiment 6, the number of refrigerant sensors or detection circuits may be three or more.

[0081]

The present invention may also employ a configuration in which a plurality of refrigerant leakage detection devices placed in a plurality of rooms are connected to one another and a detection system is used to manage the refrigerant leakage detection devices. The premise of connecting a plurality of refrigerant leakage detection devices has been that a contact is closed in the event of leakage or failure, and is opened in normal operation and power outage. However, this configuration requires connecting contacts in parallel and results in poor workability. When the contacts are connected in parallel, the logic results in signal = Open' = 'normal' even when some contacts are skipped by mistake in the connecting work. The present invention may therefore employ a configuration in which the contact logic in the event of leakage is set to open and a plurality of contacts are connected in series. Fig. 15 is a schematic diagram in which contacts of a plurality of refrigerant leakage detection devices 60 are connected in series. In the example of Fig. 15, a leakage turns the contact output to open and stops the excitation of a signal output unit X in a detection system 500, thereby supplying electricity to a contact Y. This operation turns on an alarm 510.

Reference Signs List [0082] outdoor unit 1A heat source apparatus 2 flow dividing controller

10, 10A air-conditioning system 11 compressor 12,310 fan 13 controller 14 water heat exchanger 15 cooling tower 16 water pump 21 mode switching unit 22 inspection instruction unit 23 determination unit 24 display control unit 25 clock unit 31,32,33 indoor unit 40 centralized controller 41,42, 43 remote controller 51, 52, 52a, 52b, 53, 54, 55, 56 refrigerant sensor 60, 61,62, 62A, 62B, 62C, 62D, 62E, 63, 64, 65 refrigerant leakage detection device 71,72, 73, 74 alarm 81, 82, 83 cutoff valve 90, 91, 92,93 ventilation device 100 building 101 monitor room 102,103 residential room 104 machine room 321 casing322 opening 410,631 display unit 500 detection system 510 alarm 621,621a, 621b detection circuit

622 control unit 623 drive circuit 624 power circuit 625 storage unit 626 communication unit627, 628, 629, X signal output unit 630, 630a,

630b input switching circuit 632 910 wind velocity sensor operation unit 810 flow rate sensor AC alternating current source Y contact

Claims

CLAIMS [Claim 1]

A refrigerant leakage detection device, comprising: a plurality of detection circuits configured to detect output of at least one refrigerant sensor; and a control unit configured to determine whether or not refrigerant has leaked and whether or not an abnormality has occurred in the plurality of detection circuits on a basis of output from the plurality of detection circuits.
[Claim 2]

The refrigerant leakage detection device of claim 1, wherein the at least one refrigerant sensor comprises a plurality of refrigerant sensors, and the plurality of detection circuits are each configured to detect output of a corresponding one of the plurality of refrigerant sensors, and wherein the control unit is configured to determine whether or not an abnormality has occurred in the plurality of detection circuits or in the plurality of refrigerant sensors on a basis of output from the plurality of detection circuits.
[Claim 3]

The refrigerant leakage detection device of claim 2, wherein the plurality of refrigerant sensors each configured to output to a corresponding one of the plurality of detection circuits differ from one another in precision.
[Claim 4]

A refrigerant leakage detection device, comprising:

at least one detection circuit configured to detect output of a refrigerant sensor and a reference voltage alternatingly; and a control unit configured to determine whether or not an abnormality has occurred in the at least one detection circuit on a basis of output from the at least one detection circuit, and to activate a safety device when an abnormality is determined to have occurred in the at least one detection circuit.
[Claim 5]

The refrigerant leakage detection device of claim 4,

5 wherein the at least one detection circuit comprises a plurality of detection circuits, and wherein the control unit is configured to determine whether or not an abnormality has occurred in the plurality of detection circuits on a basis of output from the plurality of detection circuits, and to activate the safety device when an

10 abnormality is determined to have occurred in one of the plurality of detection circuits.