Air conditioner

Abstract

To provide an air conditioner enabling a coolant detection sensor to be used for a long period while securing safety.SOLUTION: An air conditioner comprises an outdoor unit mounted with a compressor, an indoor unit, a coolant detection sensor which is installed inside the indoor unit and detects a leakage of a coolant, and a control section which controls operation of the coolant detection sensor. The control section controls an energization time rate of the coolant detection sensor.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present disclosure relates to an air conditioner.

Background Art

[0002] Conventionally, in an air conditioner, a technique for detecting refrigerant leakage has been known (see, for example, Patent Document 1). The air conditioner described in Patent Document 1 includes a semiconductor-type first refrigerant detection sensor that detects refrigerant leakage, a second refrigerant detection sensor that detects refrigerant leakage by a detection method different from that of the first refrigerant detection sensor, and a control unit that controls the operations of the first refrigerant detection sensor and the second refrigerant detection sensor. In Patent Document 1, the control unit controls to heat and operate the first refrigerant detection sensor during the operation of the air conditioner and to operate the second refrigerant detection sensor during the stop of the air conditioner. Thereby, in Patent Document 1, the deterioration over time of the semiconductor-type first refrigerant detection sensor is suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides an air conditioner that can ensure safety and enable the refrigerant detection sensor to be used for a long period of time.

Means for Solving the Problems

[0005] In the air conditioner according to the present disclosure, in an air conditioner including an outdoor unit having a compressor, an indoor unit, a refrigerant detection sensor provided in the indoor unit for detecting refrigerant leakage, and a control unit for controlling the operation of the refrigerant detection sensor, the control unit controls the energization time ratio to the refrigerant detection sensor The control unit executes intermittent energization control for intermittently energizing the refrigerant detection sensor, and the non-energization time of the refrigerant detection sensor in the intermittent energization control is within the time required to detect refrigerant leakage after the refrigerant leaks from the refrigerant pipe. .

Effects of the Invention

[0006] According to the present disclosure, it is possible to use a refrigerant detection sensor for a long period while ensuring safety.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0008] (Findings etc. underlying the present disclosure) When the inventors arrived at the present disclosure, there was a technique of suppressing the integrated energization time of each refrigerant detection sensor and suppressing the deterioration over time of the refrigerant detection sensor by providing a plurality of refrigerant detection sensors for detecting refrigerant leakage in an indoor unit and appropriately using the plurality of refrigerant detection sensors.

[0009] However, in the conventional technology, since a plurality of refrigerant detection sensors are required, the inventors have found that it is not a technique capable of achieving a long life in the case of detecting refrigerant leakage using a single refrigerant detection sensor, and in order to solve that problem, they have come to constitute the subject matter of the present disclosure. The present disclosure provides an air conditioner that can use a refrigerant detection sensor for a long period while ensuring safety.

[0010] Hereinafter, embodiments will be described in detail with reference to the drawings. However, the description may be omitted in more detail than necessary. For example, details of well-known matters may be omitted, or redundant descriptions of substantially the same configurations may be omitted. This is to avoid the following description from becoming overly redundant and to facilitate the understanding of those skilled in the art. Note that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0011] (Embodiment 1) Hereinafter, Embodiment 1 will be described with reference to FIGS. 1 to 8. FIG. 1 is a side cross-sectional view of the air conditioner in Embodiment 1. FIG. 2 is a plan view of the air conditioner in Embodiment 1.

[0012] [1-1. Configuration of Indoor Unit] As shown in FIGS. 1 and 2, the air conditioner 1 in the present embodiment includes an indoor unit 5. The indoor unit 5 includes a box-shaped housing 10. The housing 10 includes a top plate 11 and a bottom plate 12. The left side of the housing 10 in FIG. 1 is a blower chamber 13, and the right side of the housing 10 in FIG. 1 is a heat exchanger chamber 14 that houses the indoor heat exchanger 20. The blower chamber 13 and the heat exchanger chamber 14 are partitioned by a partition wall 15.

[0013] An intake port 16 for taking in indoor air is provided behind the blower chamber 13, and a plurality (three in the present embodiment) of scroll casings 31 that house sirocco fans 30 as indoor fans are provided inside the blower chamber 13. An air outlet 17 is provided on the front side of the indoor heat exchanger 20 in the heat exchanger chamber 14.

[0014] The scroll casing 31 is formed at both ends of the scroll casing 31, and includes a fan opening 32 that sucks in the air flowing in from the suction port 16 due to the rotation of the sirocco fan 30, and a blower passage 33 that discharges the air sucked from the fan opening 32 toward the heat exchanger chamber 14. An electric motor 34 is provided between the scroll casings 31. The electric motor 34 is connected to the rotating shaft 35 of the sirocco fan 30 and rotationally drives the sirocco fan 30.

[0015] The sirocco fan 30 is a centrifugal fan. By operating the sirocco fan 30, air is sucked in from the suction port 16, flows into the scroll casing 31 from the direction of the rotating shaft 35 through the fan opening 32, is blown out from the blower passage 33 to the indoor heat exchanger 20, and the conditioned air that has undergone heat exchange in the indoor heat exchanger 20 is discharged into the room from the blowout port 17. A drain pan 21 is disposed at the lower part of the indoor heat exchanger 20 accommodated in the heat exchanger chamber 14 in FIG. 1.

[0016] Also, as shown in FIG. 2, in the present embodiment, a first partition plate 23 is provided in the heat exchanger chamber 14 to partition a heat exchange region 22 of the indoor heat exchanger 20 and a piping connection region where refrigerant pipes 47, 48 (see FIG. 4) from the outdoor unit 40 (see FIG. 4) are connected at one end side of the indoor heat exchanger 20. The piping connection region is a first region 24. Further, a second partition plate 25 is provided in the heat exchanger chamber 14 to partition the heat exchange region 22 and a bend portion region where the refrigerant pipes of the indoor heat exchanger 20 are folded back at the other end side of the indoor heat exchanger 20. The bend portion region is a second region 26.

[0017] A refrigerant duct 36 is provided in the heat exchanger chamber 14. The refrigerant duct 36 extends in the width direction of the heat exchanger chamber 14. An opening is provided at one end in the width direction of the refrigerant duct 36, and the refrigerant duct 36 is configured to communicate with the first region 24 from the first partition plate 23. Also, an opening is provided at the other end in the width direction of the refrigerant duct 36, and the refrigerant duct 36 is configured to communicate with the second region 26 from the second partition plate 25. Therefore, the first region 24 and the second region 26 are spatially connected through the refrigerant duct 36.

[0018] A refrigerant detection sensor 50 for detecting refrigerant leakage is disposed in the first region 24. The refrigerant detection sensor 50 can detect refrigerant leakage in the first region 24. Further, when refrigerant leakage occurs in the second region, the refrigerant detection sensor 50 can detect the refrigerant leakage based on the refrigerant flowing into the first region 24 through the refrigerant duct 36. The refrigerant detection sensor 50 may be provided inside the refrigerant duct 36. Further, the refrigerant detection sensor 50 may be provided in the second region 26.

[0019] FIG. 3 is a diagram schematically showing the refrigerant detection sensor 50 according to the first embodiment. The refrigerant detection sensor 50 can be composed of any sensor as long as it can detect the refrigerant, such as a semiconductor sensor or an infrared sensor. In the present embodiment, the case where the refrigerant detection sensor 50 is composed of a semiconductor sensor will be described. The refrigerant detection sensor 50 includes a circuit board 51 electrically connected to a control unit, a sensor element (detection unit) 52 provided on the circuit board 51, a heater 53 for heating the sensor element 52, and a cylindrical body (housing) 54 for housing the sensor element 52 and the heater 53 inside. Refrigerant can enter the inside of the cylindrical body 54 through the opening 54a of the cylindrical body 54, whereby the refrigerant can reach the sensor element 52. A heat insulating material 55 is provided on the outer peripheral portion of the cylindrical body 54. The heat insulating material 55 covers the cylindrical body 54. The heat insulating material 55 facilitates heat insulation between the inside and outside of the cylindrical body 54. The sensor element 52 is thermally insulated by the heat insulating material 55. Although it is desirable that the heat insulating material 55 is provided on the outer peripheral portion of the cylindrical body 54, it may be omitted.

[0020] [1-2. Configuration of the air conditioner] Next, the configuration of the air conditioner 1 will be described. FIG. 4 is a refrigeration cycle diagram showing the configuration of the air conditioner 1 according to the first embodiment. As shown in Fig. 4, the air conditioner 1 includes an outdoor unit 40 and an indoor unit 5. The outdoor unit 40 houses a compressor 41, a four-way valve 42 for switching the refrigerant flow path, an outdoor heat exchanger 43, an outdoor fan 44, and an outdoor throttle device 45. The compressor 41, the four-way valve 42, the outdoor heat exchanger 43, and the outdoor throttle device 45 are sequentially connected by a refrigerant pipe 46.

[0021] The indoor unit 5 houses an indoor heat exchanger 20, an indoor throttle device 27, and a sirocco fan 30 respectively. The indoor heat exchanger 20 and the indoor throttle device 27 are connected via a refrigerant pipe 28. The compressor 41 of the outdoor unit 40 and the indoor heat exchanger 20 of the indoor unit 5 are connected by a liquid refrigerant pipe 47 and a gas refrigerant pipe 48. Refrigerant shut-off valves 49 are provided near the indoor unit 5 of the liquid refrigerant pipe 47 and the gas refrigerant pipe 48 respectively.

[0022] [1-3. Control Configuration] Next, the control configuration of the present embodiment will be described. Fig. 5 is a block diagram showing the control configuration of the present embodiment. As shown in Fig. 5, the air conditioner 1 includes a control unit 60. The control unit 60 includes, for example, a processor that executes programs such as a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit), and memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The processor reads out the control program stored in the memory and executes processing, and various processes are executed by the cooperation of hardware and software.

[0023] The control unit 60 controls the compressor 41, the outdoor throttle device 45, the outdoor fan 44, the sirocco fan 30 of the indoor unit 5, and the indoor throttle device 27 of the outdoor unit 40 respectively based on the control program. Based on the detection signal of the refrigerant detection sensor 50 in the indoor unit 5, the control unit 60 detects refrigerant leakage. Also, based on the detection signal of the refrigerant detection sensor 50, the control unit 60 controls the opening and closing of the refrigerant shut-off valve 49 and the indoor throttling device 27.

[0024] The control unit 60 of the present embodiment controls the operation of the refrigerant detection sensor 50. The control unit 60 controls the energization and non-energization of the refrigerant detection sensor 50 to control the operation of the refrigerant detection sensor 50.

[0025] Generally, the refrigerant detection sensor 50 deteriorates as the integrated energization time, which is the cumulative energization time, becomes longer. Therefore, when refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5, the control unit 60 controls the energization time ratio of the refrigerant detection sensor 50 to be larger than when refrigerant is not flowing through the refrigerant pipe 28 in the indoor unit 5. The energization time ratio of the refrigerant detection sensor 50 is, for example, "energization time to the refrigerant detection sensor 50÷(energization time to the refrigerant detection sensor 50 + non-energization time to the refrigerant detection sensor 50)".

[0026] When refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5, the refrigerant pressure in the indoor unit 5 increases, and the concentration increase rate of the leaked refrigerant when the refrigerant pipe 28 is damaged becomes faster. Therefore, by increasing the energization time ratio of the refrigerant detection sensor 50, the leaked refrigerant can be detected quickly. On the other hand, when refrigerant is not flowing through the refrigerant pipe 28 in the indoor unit 5, the refrigerant pressure in the indoor heat exchanger 20 decreases, and the concentration increase rate of the leaked refrigerant when the refrigerant pipe 28 is damaged becomes slower. Therefore, when refrigerant is not flowing through the refrigerant pipe 28 in the indoor unit 5, the control unit 60 reduces the energization time ratio of the refrigerant detection sensor 50 to detect refrigerant leakage while suppressing the integrated energization time of the refrigerant detection sensor 50.

[0027] Here, when refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5, for example, there is a cooling operation or a heating operation. Also, when refrigerant is not flowing through the refrigerant pipe 28 in the indoor unit 5, for example, there is an air conditioning operation stop state, a thermo-off operation, or a blowing operation. The thermo-off operation is an operation in which, since the room temperature has reached the set temperature, the cooling operation and the heating operation are not performed, and the sirocco fan 30 is driven.

[0028] Also, as a method of increasing the energization time ratio of the refrigerant detection sensor 50, for example, there is continuous energization control in which the refrigerant detection sensor 50 is continuously energized. Also, as a method of decreasing the energization time ratio of the refrigerant detection sensor 50, for example, there is intermittent energization control in which the refrigerant detection sensor 50 is repeatedly energized and de-energized.

[0029] In the present embodiment, a configuration will be described in which the control unit 60 executes continuous energization control during the operation of the compressor 41 and executes intermittent energization control during the stop of the compressor 41.

[0030] FIG. 6 is a timing chart of the operation of the compressor 41 and the energization control of the refrigerant detection sensor 50. The intermittent energization control of the present embodiment periodically repeats energization and de-energization. Specifically, when starting the intermittent energization control, the control unit 60 continuously energizes the refrigerant detection sensor 50 for a predetermined energization time Ton. When the energization time Ton has elapsed, the control unit 60 stops the energization of the refrigerant detection sensor 50 for a predetermined de-energization time Toff. Also, when the de-energization time Toff has elapsed, the control unit 60 continuously energizes the refrigerant detection sensor 50 for the energization time Ton. In this way, during the stop (OFF) of the compressor 41, the control unit 60 executes intermittent energization control by periodically repeating energization for the energization time Ton and de-energization for the de-energization time Toff with a period P. The period P is the sum of the energization time Ton and the de-energization time Toff. In FIG. 6, due to the operation (ON) and stop (OFF) of the compressor 41, the period C1 in which continuous energization control is executed and the period C2 in which intermittent energization control is executed are switched.

[0031] FIG. 7 is a diagram for explaining the non - energization time Toff. The non - energization time Toff is set based on various requirements. Specifically, in the air conditioner 1, when refrigerant leakage above a certain concentration occurs, it is required to detect the refrigerant leakage within a predetermined specified time (first time) T1 after the refrigerant leakage occurs. The specified time T1 is, for example, a time predetermined by JRA (Japan Refrigeration and Air - Conditioning Industry Association) or EN (European Telecommunications Standards Institute).

[0032] Also, the refrigerant detection sensor 50 requires warm - up until it can detect refrigerant leakage. That is, the refrigerant detection sensor 50 cannot detect refrigerant leakage simultaneously with the start of energization. Until the warm - up time (second time) T2 has elapsed after the start of energization, it cannot enter a state where it can detect refrigerant leakage. The warm - up time T2 is a value based on the specifications and characteristics of the refrigerant detection sensor 50.

[0033] The non - energization time Toff is set based on the difference T1 - T2 between the preset specified time T1 required to detect refrigerant leakage after the refrigerant leaks, as shown by the arrows B1 - B3 in FIG. 7, and the warm - up time T2 from the start of energization of the refrigerant detection sensor 50 until the refrigerant detection sensor 50 can detect refrigerant leakage. In the present embodiment, the non - energization time Toff is set to a value obtained by subtracting a predetermined margin Δ from the difference T1 - T2. However, the non - energization time Toff may be set without subtracting the margin Δ from the difference T1 - T2.

[0034] Here, in the present embodiment, the refrigerant detection sensor 50 is a semiconductor - type sensor. Therefore, the time required for the refrigerant detection sensor 50 to reach a predetermined detectable temperature (a temperature between 300°C and 400°C) from room temperature after the start of energization is defined as the warm - up time T2.

[0035] The above warm-up time T2 may be a time including a margin time in addition to the time required to reach the detectable temperature from room temperature. The margin time is, for example, the time from when refrigerant leakage occurs until the refrigerant detection sensor 50 can detect the refrigerant leakage (the leaked refrigerant can reach the sensor element 52). Specifically, when refrigerant leakage occurs in the second region 26, the time until the leaked refrigerant reaches the first region 24 through the refrigerant duct 36 may be used as the margin time. Thereby, after the elapse of the warm-up time T2, refrigerant leakage can be accurately detected.

[0036] Note that when power supply is stopped as in this embodiment, heating of the sensor element 52 of the refrigerant detection sensor 50 is stopped, so the sensor element 52 is generally cooled. However, depending on the timing of restarting the power supply, the sensor element 52 is heated from a temperature higher than room temperature, and the time required for warm-up of the refrigerant detection sensor 50 is shortened. In particular, when the refrigerant detection sensor 50 is covered with the heat insulating material 55 as in this embodiment, the warm-up time T2 tends to be shortened due to the heat retaining effect of the heat insulating material 55. Therefore, as shown by the arrow B2 in FIG. 7, based on the warm-up time T2 that is shorter than the warm-up time T2 at room temperature, the non-power-on time Toff may be set and intermittent power supply control may be executed. This warm-up time T2 is set based on, for example, experiments. Thereby, the integrated energization time of the refrigerant detection sensor 50 can be suppressed.

[0037] Note that the shorter the energization time Ton is, the easier it is to suppress the integrated energization time.

[0038] In addition, since the refrigerant detection sensor 50 is more likely to deteriorate as the integrated energization time becomes longer, the time required for warming up may become longer. Therefore, as shown by the arrow B3 in FIG. 7, intermittent energization control may be executed based on the non-energization time Toff that becomes shorter as the integrated energization time becomes longer. In this case, for example, the control unit 60 stores a preset function for calculating the non-energization time Toff based on the integrated energization time of the refrigerant detection sensor 50, and calculates the non-energization time Toff based on the integrated energization time from that function. Then, the control unit 60 may stop energization only for the calculated non-energization time Toff. Also, the integrated energization time of the refrigerant detection sensor 50 may be divided stepwise in advance, and an optimal non-energization time Toff may be obtained according to the stage to which the integrated energization time belongs. In this case, the relationship between the integrated energization time and the non-energization time Toff can be stored in a look-up table. Note that the life of the refrigerant detection sensor 50 can be determined based on the integrated energization time. For this reason, in the air conditioner 1, the integrated energization time is measured by the control unit 60.

[0039] [1-4. Operation] Regarding the air conditioner 1 configured as described above, its operation and action will be described below. FIG. 8 is a flowchart showing the processing flow of the control unit 60. The control unit 60 starts the processing of FIG. 8 when power is supplied to the air conditioner 1. When starting the processing of FIG. 8, the control unit 60 determines whether the compressor 41 is in operation (step ST11). In the present embodiment, the operation of the compressor 41 means the period from when the compressor 41 starts operating to when the compressor 41 ends operating. Also, when the compressor 41 is not in operation, that is, when the compressor 41 is stopped, it means the period from when the compressor 41 ends operating to when the compressor 41 starts operating.

[0040] When the control unit 60 determines that the compressor 41 is in operation (step ST11: YES), it executes continuous energization control on the refrigerant detection sensor 50 (step ST12). That is, the control unit 60 executes continuous energization control from when the compressor 41 starts operating until the compressor 41 ends operation.

[0041] When the control unit 60 determines that the compressor 41 is stopped (step ST11: NO), it executes intermittent energization control on the refrigerant detection sensor 50 (step ST13). That is, the control unit 60 executes intermittent energization control from when the compressor 41 ends operation until the compressor 41 starts operation.

[0042] Generally, when the refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5, such as when the compressor 41 is in operation, the pressure of the refrigerant pipe 28 in the indoor unit 5 is high. Therefore, if refrigerant leakage occurs, the concentration increase rate of the leaked refrigerant is fast. In this embodiment, when the compressor 41 is in operation, by continuously energizing the refrigerant detection sensor 50, it is easier to quickly detect refrigerant leakage.

[0043] Also, when the compressor 41 is stopped, etc., when the refrigerant is not flowing through the refrigerant pipe 28 in the indoor unit 5, the pressure of the refrigerant pipe 28 in the indoor unit 5 is low. Therefore, if refrigerant leakage occurs, the concentration increase rate of the leaked refrigerant is slow, so-called slow leak is likely to occur. Therefore, the necessity of quickly detecting refrigerant leakage is smaller than when the compressor 41 is in operation. Also, it is likely to take time until the refrigerant leakage can be detected. Thus, in this embodiment, when the compressor 41 is stopped, by executing intermittent energization control, while suppressing the integrated energization time of the refrigerant detection sensor 50, it is possible to detect refrigerant leakage.

[0044] Specifically, as shown by the arrow A1 in FIG. 6, when the compressor 41 stops (OFF), the refrigerant detection sensor 50 is continuously energized for the energization time Ton, and then the energization to the refrigerant detection sensor 50 is stopped for the non-energization time Toff, and these are repeated until the compressor 41 starts operating. At this time, for example, if refrigerant leakage occurs at time L1 immediately after the end of the energization time Ton, since the refrigerant detection sensor 50 is not operating, the refrigerant leakage cannot be detected immediately after the leakage. However, in the present embodiment, since the non-energization time Toff is set based on the difference T1 - T2 between the specified time T1 and the warm-up time T2, the warm-up of the refrigerant detection sensor 50 is completed at time L4 before the specified time T1 has elapsed since time L1. Therefore, at time L4, the refrigerant detection sensor 50 can detect the refrigerant leakage that occurred at time L1, so the refrigerant leakage can be detected within the specified time T1 after the refrigerant has leaked.

[0045] Similarly, when refrigerant leakage occurs at time L2 within the non-energization time Toff or at time L3 within the warm-up time T2, the leakage cannot be detected immediately after the refrigerant leakage. However, at time L4, since the refrigerant detection sensor 50 has completed warm-up and can detect refrigerant leakage, the refrigerant leakage can be detected within the specified time T1 after the occurrence of the refrigerant leakage. Therefore, in the present embodiment, while using a single refrigerant detection sensor 50, it is possible to ensure safety and enable the long-term use of the refrigerant detection sensor 50.

[0046] [1-5. Effects, etc.] As described above, in the present embodiment, in the air conditioner 1 including the outdoor unit 40 provided with the compressor 41, the indoor unit 5, the refrigerant detection sensor 50 provided in the indoor unit 5 for detecting refrigerant leakage, and the control unit 60 for controlling the operation of the refrigerant detection sensor 50, the control unit 60 controls the energization time ratio to the refrigerant detection sensor 50. Thereby, in the present embodiment, it is possible to ensure safety and enable the long-term use of the refrigerant detection sensor 50.

[0047] As in the present embodiment, the control unit 60 executes intermittent energization control for intermittently energizing the refrigerant detection sensor 50, and the non-energization time Toff of the refrigerant detection sensor 50 in the intermittent energization control may be within the specified time T1 required to detect refrigerant leakage after the refrigerant has leaked from the refrigerant pipe 28. This makes it possible to suppress the integrated energization time of the refrigerant detection sensor 50 while enabling the refrigerant detection sensor 50 to be energized within the specified time T1. Therefore, in the present embodiment, the refrigerant detection sensor 50 can be used for a long period while ensuring safety.

[0048] When, as in the present embodiment, the warm-up time T2 is defined as the time from when energization of the refrigerant detection sensor 50 starts until the refrigerant detection sensor 50 becomes capable of detecting the refrigerant, the control unit 60 may control the non-energization time Toff of the refrigerant detection sensor 50 in the intermittent energization control to be within the time obtained by subtracting the warm-up time T2 from the specified time T1. This makes it possible to detect refrigerant leakage within the specified time T1 even when the refrigerant detection sensor 50 returns from non-energization in the case of refrigerant leakage.

[0049] As in the present embodiment, the refrigerant detection sensor 50 may include a sensor element 52, a heater 53 that heats the sensor element 52, and a cylindrical body 54 that houses the sensor element 52 and the heater 53 and has an opening 54a through which the refrigerant flows in. Further, the control unit 60 may control so that the non-energization time Toff in the intermittent energization control is longer for the refrigerant detection sensor 50 provided with the heat insulating material 55 on the cylindrical body 54 than for the refrigerant detection sensor 50 not provided with the heat insulating material 55 on the cylindrical body 54. This makes it easier to shorten the warm-up time T2 due to the heat insulation effect of the heat insulating material 55. For this reason, even if the non-energization time Toff is lengthened, refrigerant leakage can be detected within the specified time T1, and the integrated energization time of the refrigerant detection sensor 50 can be suppressed.

[0050] As in the present embodiment, the control unit 60 may control so that the non-energization time Toff in the intermittent energization control becomes shorter as the integrated energization time of the refrigerant detection sensor 50 becomes longer. As a result, even if the time required for the warm-up of the refrigerant detection sensor 50 becomes longer with use, the non-energization time Toff becomes shorter, so that it is possible to detect refrigerant leakage within the specified time T1. Therefore, while ensuring safety, the refrigerant detection sensor 50 can be used for a long period of time.

[0051] As in the present embodiment, the control unit 60 may control so that the energization time ratio is larger when refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5 than when refrigerant is not flowing through the refrigerant pipe 28 in the indoor unit 5. As a result, when refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5, the refrigerant pressure in the indoor unit 5 increases, and the concentration rising speed of the leaked refrigerant when the refrigerant pipe 28 is damaged becomes faster. Therefore, by increasing the energization time ratio of the refrigerant detection sensor 50, the leaked refrigerant can be quickly detected. On the other hand, when refrigerant is not flowing through the refrigerant pipe 28 in the indoor unit 5, the refrigerant pressure of the indoor heat exchanger 20 decreases, and the concentration rising speed of the leaked refrigerant when the refrigerant pipe 28 is damaged becomes slower. Therefore, by reducing the energization time ratio of the refrigerant detection sensor 50, it is possible to detect refrigerant leakage while suppressing the integrated energization time of the refrigerant detection sensor 50. Therefore, while ensuring safety, the refrigerant detection sensor 50 can be used for a long period of time.

[0052] As in the present embodiment, the control unit 60 may execute continuous energization control to continuously energize the refrigerant detection sensor 50 when refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5, and execute intermittent energization control to intermittently energize the refrigerant detection sensor 50 when refrigerant is not flowing through the refrigerant pipe 28 of the indoor unit 5. As a result, by simple control, it is possible to control so that the energization time ratio is larger when refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5 than when refrigerant is not flowing through the refrigerant pipe 28 in the indoor unit 5. Also, by continuous energization control, when refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5, refrigerant leakage can be quickly detected.

[0053] As in this embodiment, the control unit 60 may execute continuous power supply control when the compressor 41 is driving, and may execute intermittent power supply control when the compressor 41 is not driving. Thereby, in accordance with the driving and stopping of the compressor 41, it is possible to control such that the power-on time ratio is larger when the refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5 than when the refrigerant is not flowing through the refrigerant pipe 28 in the indoor unit 5.

[0054] (Other embodiments) As described above, as an example of the technology disclosed in this application, Embodiment 1 has been described. However, the technology in the present disclosure is not limited thereto, and can also be applied to embodiments in which changes, replacements, additions, omissions, etc. are made. Further, it is also possible to combine the components described in Embodiment 1 above to form a new embodiment. Therefore, other embodiments will be exemplified below.

[0055] In the indoor unit 5 of the air conditioner 1 of Embodiment 1, a configuration in which a single refrigerant detection sensor 50 is provided has been described, but a plurality of refrigerant detection sensors may be provided. For example, a refrigerant detection sensor 50 may be provided in the first region 24 and a second refrigerant detection sensor may be provided in the second region 26. In this case, each of the refrigerant detection sensor 50 and the second refrigerant detection sensor may be subjected to power supply control during the operation of the compressor 41 and intermittent power supply control during the stop of the compressor 41.

[0056] In the intermittent power supply control of Embodiment 1, when the power-on for the power-on time Ton and the non-power-on for the non-power-on time Toff are periodically repeated with the period P, a configuration in which the non-power-on time Toff follows the power-on time Ton has been described, but the time for the non-power-on time Toff may be at any timing within the period P. That is, for example, as indicated by the arrow A2 in FIG. 6, the non-power-on time Toff may be set. In the arrow A2 in FIG. 6, the total of the power-on times within the period P is the power-on time Ton.

[0057] In Embodiment 1, the configuration has been described with one indoor unit 5 provided, but the present invention is not limited to this, and a configuration in which a plurality of indoor units are provided may also be used. In this case, for example, when refrigerant is flowing through the refrigerant pipe 28 of one of the two indoor units and no refrigerant is flowing through the refrigerant pipe 28 of the other indoor unit, it is preferable that the control unit 60 performs continuous power supply control for one indoor unit and intermittent power supply control for the other indoor unit.

[0058] In Embodiment 1, a refrigerant shut-off valve 49 for shutting off the flow of refrigerant in the refrigerant pipe 28 is provided, and when the control unit 60 closes the refrigerant shut-off valve 49 due to factors other than refrigerant leakage detection, the control unit 60 may execute power-off control for stopping the power supply to the refrigerant detection sensor 50. In this case, for example, when power is supplied to the air conditioner 1, the control unit 60 starts to determine whether the refrigerant shut-off valve 49 is closed. At this time, the control unit 60 repeatedly determines whether the refrigerant shut-off valve 49 is closed until it determines that the refrigerant shut-off valve 49 is closed. Then, when the control unit 60 determines that the refrigerant shut-off valve 49 is closed, it determines whether refrigerant leakage has occurred. Then, when the control unit 60 determines that no refrigerant leakage has occurred, it executes power-off control. In this way, when the control unit 60 closes the refrigerant shut-off valve 49 due to factors other than refrigerant leakage detection, the control unit 60 may execute power-off control for stopping the power supply to the refrigerant detection sensor 50. When the refrigerant shut-off valve 49 is closed, even if the refrigerant pipe 28 is damaged by any chance, since the amount of leaked refrigerant is small, safety can be ensured even if the power supply to the refrigerant detection sensor 50 is stopped. The case where the refrigerant shut-off valve 49 is closed due to factors other than refrigerant leakage detection is an operation in which no refrigerant flows through the refrigerant pipe 28 in the indoor unit 5, for example, during air conditioning operation stop, during air supply operation, and during thermo-off operation.

[0059] In the air conditioner 1 according to the first embodiment, as an example of increasing the energization time ratio to the refrigerant detection sensor 50, the control unit 60 has been described as having a configuration in which the refrigerant detection sensor 50 is continuously energized. The present invention is not limited to this. When refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5, the energization time ratio to the refrigerant detection sensor 50 may be larger than when no refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5. For example, when refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5, the refrigerant detection sensor 50 may basically be energized and controlled to be temporarily de-energized only for a short period (for example, 5 seconds). Further, when refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5, the control unit 60 may control the refrigerant detection sensor 50 to be intermittently energized and control the non-energization time Toff to be shorter when refrigerant is flowing through the indoor unit 5 than when refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5.

[0060] In the first embodiment, the control unit 60 has been described as having a configuration in which intermittent control operation is executed when no refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5, but the present invention is not limited to this. For example, even when refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5, if the refrigerant pressure in the refrigerant pipe 28 in the indoor unit 5 is relatively low, the control unit 60 may execute intermittent control operation because the concentration increase rate of the leaked refrigerant is relatively slow. As a method for obtaining the refrigerant pressure in the refrigerant pipe 28 in the indoor unit 5, for example, a refrigerant pressure sensor may be used. Also, within a predetermined time from the start of operation of the compressor 41 after the compressor 41 has stopped, it may be estimated that the refrigerant pressure in the refrigerant pipe 28 in the indoor unit 5 is relatively low.

[0061] In the air conditioner 1 according to the first embodiment, the control unit 60 has been described as having a configuration in which intermittent energization control is executed while the compressor 41 is stopped. In the present invention, continuous energization control may be executed when refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5. For example, after the compressor 41 has stopped, the control unit 60 may execute continuous energization control for a predetermined time and execute intermittent energization control after a predetermined time has elapsed since the compressor 41 stopped. This is because even after the compressor 41 has stopped, refrigerant is flowing through the refrigerant pipe 28 in the indoor unit 5 for a predetermined time, the refrigerant pressure in the refrigerant pipe 28 is higher than when no refrigerant is flowing through the refrigerant pipe 28, and the concentration increase rate of the leaked refrigerant is faster.

[0062] In the air conditioner 1 of Embodiment 1, the control unit 60 has been described as executing continuous energization control during the operation of the compressor 41. However, the present invention is not limited to this. For example, within a predetermined time after the start of the operation of the compressor 41, intermittent energization control may be executed, and continuous energization control may be executed after a predetermined time has elapsed since the start of the operation of the compressor 41. This is because within a predetermined time after the start of the operation of the compressor 41, the flow rate of the refrigerant in the refrigerant pipe 28 of the indoor unit 5 is small and the refrigerant pressure is relatively low, so the rate of increase in the concentration of the leaked refrigerant is relatively slow.

[0063] In Embodiment 1, the non-energization time Toff in the intermittent energization control has been described as being within the specified time T1 predetermined by JRA. However, the present invention is not limited to this. For example, when the sirocco fan (indoor fan) 30 is driven, such as during the blowing operation, the non-energization time Toff of the intermittent energization control may be set to be equal to or longer than the specified time T1. When the sirocco fan 30 is driven, even if the refrigerant leaks, the leaked refrigerant flows due to the sirocco fan 30, and an increase in the concentration of the leaked refrigerant can be suppressed.

[0064] In Embodiment 1, when refrigerant is flowing in the refrigerant pipe 28 in the indoor unit 5, the control unit 60 executes continuous energization control to continuously energize the refrigerant detection sensor 50. When refrigerant is not flowing in the refrigerant pipe 28 of the indoor unit 5, the control unit 60 executes intermittent energization control to intermittently energize the refrigerant detection sensor 50. However, alternatively, when refrigerant is flowing in the refrigerant pipe 28 in the indoor unit 5, the control unit 60 executes continuous energization control to continuously energize the refrigerant detection sensor 50. When refrigerant is not flowing in the refrigerant pipe 28 of the indoor unit 5, the control unit 60 may execute energization stop control to stop the energization of the refrigerant detection sensor 50. By the energization stop control, the integrated energization time of the refrigerant detection sensor 50 can be effectively suppressed.

[0065] In addition, in Embodiment 1, the control unit 60 was described as having a configuration in which continuous energization control is executed when the compressor 41 is driving, and intermittent energization control is executed when the compressor 41 is not driving. However, alternatively, the control unit 60 may execute continuous energization control when the compressor 41 is driving, and execute energization stop control to stop energization to the refrigerant detection sensor 50 when the compressor 41 is not driving.

[0066] Also, in Embodiment 1, the control unit 60 executed intermittent energization control during air conditioning operation stop, thermo-off operation, or blowing operation. However, the control unit 60 may execute energization stop control to stop energization to the refrigerant detection sensor 50 during air conditioning operation stop, thermo-off operation, or blowing operation.

[0067] The indoor unit 5 of the air conditioner 1 according to Embodiment 1 illustrated a so-called two-way ceiling cassette type indoor unit, but is not limited thereto, and may be a four-way ceiling cassette type indoor unit, and the present disclosure may be applied to a refrigerant detection sensor provided in a four-way ceiling cassette type indoor unit.

[0068] Note that the above-described embodiments are for exemplifying the technology in the present disclosure, and thus various changes, replacements, additions, omissions, etc. can be made within the scope of the claims or the equivalent scope thereof.

Industrial Applicability

[0069] The present disclosure is suitably applicable to an air conditioner using a refrigerant detection sensor.

Explanation of Signs

[0070] 1 Air conditioner 5 Indoor unit 28 Refrigerant pipe 40 Outdoor unit 41 Compressor 50 Refrigerant detection sensor 52 Sensor element 53 Heater 54a Opening 54 Cylindrical body (housing) 55 Heat insulating material 60 Control unit T1 Specified time T2 Warm-up time Toff Non-energization time

Claims

1. An air conditioner comprising: an outdoor unit equipped with a compressor; an indoor unit; a refrigerant detection sensor provided in the indoor unit for detecting refrigerant leakage; and a control unit for controlling the operation of the refrigerant detection sensor. The control unit controls the energization time ratio to the refrigerant detection sensor. The control unit executes intermittent energization control for intermittently energizing the refrigerant detection sensor. In the intermittent energization control, the non-energization time of the refrigerant detection sensor is set to be within the time required to detect refrigerant leakage after refrigerant leaks from the refrigerant pipe. An air conditioner.

2. When the time from the start of energization to the refrigerant detection sensor until the refrigerant detection sensor becomes capable of detecting refrigerant is defined as the warm-up time, the control unit controls the non-energization time of the refrigerant detection sensor in the intermittent energization control to be within the time obtained by subtracting the warm-up time from the required time. The air conditioner according to Claim 1.

3. The refrigerant detection sensor includes a sensor element, a heater for heating the sensor element, and a housing that houses the sensor element and the heater and has an opening through which refrigerant flows in. The control unit controls the non-energization time in the intermittent energization control to be longer for the refrigerant detection sensor provided with a heat insulating material on the housing than for the refrigerant detection sensor not provided with a heat insulating material on the housing. The air conditioner according to Claim 2.

4. The control unit controls such that the longer the integrated energization time of the refrigerant detection sensor, the shorter the non-energization time in the intermittent energization control. The air conditioner according to Claim 2.

5. The control unit controls such that the energization time ratio is larger when refrigerant is flowing through the refrigerant pipe in the indoor unit than when no refrigerant is flowing through the refrigerant pipe in the indoor unit. The air conditioner according to Claim 1.

6. When refrigerant is flowing through the refrigerant pipe in the indoor unit, the control unit executes continuous energization control for continuously energizing the refrigerant detection sensor; when no refrigerant is flowing through the refrigerant pipe in the indoor unit, the control unit executes intermittent energization control for intermittently energizing the refrigerant detection sensor or energization stop control for stopping energization to the refrigerant detection sensor. The air conditioner according to Claim 5.

7. When the compressor is driving, the control unit executes the continuous power supply control, and when the compressor is not driving, the control unit executes the intermittent power supply control or the power supply stop control for stopping the power supply to the refrigerant detection sensor. The air conditioner according to claim 6.

8. When the air conditioning operation is stopped, the thermo-off operation is in progress, or the blowing operation is in progress, the control unit executes the intermittent power supply control or the power supply stop control for stopping the power supply to the refrigerant detection sensor. The air conditioner according to claim 6.

9. Comprising a refrigerant shut-off valve for shutting off the flow of the refrigerant, When the refrigerant shut-off valve is closed due to factors other than refrigerant leakage detection, the control unit executes the power supply stop control for stopping the power supply to the refrigerant detection sensor. The air conditioner according to claim 6.

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