Air conditioner

Abstract

To provide an air conditioner capable of surely detecting refrigerant leakage from a refrigerant circuit.SOLUTION: The control part 50 compares an initial detection temperature being a detection value in the heat exchange temperature sensor 40 immediately after the start of operation with a first detection temperature being a detection value in the heat exchange temperature sensor 40 after a predetermined time elapses from the start of operation, opens the bypass valve 36 when a predetermined first condition is satisfied, compares a second detection temperature being a detection value in the heat exchange temperature sensor 40 after a predetermined time elapses from the opening of the bypass valve 36 with the first detection temperature, and stops the operation when a predetermined second condition is satisfied. As a result, the occurrence of refrigerant leakage from the refrigerant circuit 30 can be accurately detected regardless of the temperature around the main body case 10. In addition, since the present invention can be implemented without installing an additional member such as a room temperature sensor, the cost of the product is not increased.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an air conditioner that conditions indoor air. [Background technology]

[0002] Conventionally, this type of device has a refrigerant circuit consisting of a compressor, condenser, pressure reducing device, and evaporator connected in a circular pattern by refrigerant piping, and a heat exchanger temperature sensor installed in the evaporator or condenser.The initial detected temperature, which is the detected value by the heat exchanger temperature sensor at the start of operation, is compared with the first detected temperature, which is the detected value by the heat exchanger temperature sensor after a predetermined time has elapsed since the start of operation.If the difference between the initial detected temperature and the first detected temperature is below a certain value, it is determined that a refrigerant leak has occurred and operation is stopped. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 1-95255 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with this conventional system, there is a possibility that the occurrence of a refrigerant leak cannot be accurately detected depending on the temperature environment around the evaporator or condenser where the heat exchanger temperature sensor is installed. Specifically, when a heat exchanger temperature sensor is installed in an evaporator, if the evaporator is operated in an environment where the temperature around the evaporator is lower than room temperature, the temperature of the evaporator will decrease more slowly than when it is at room temperature, even in a normal state where no refrigerant leak has occurred. As a result, the first detected temperature, which is the value detected by the heat exchanger temperature sensor a predetermined time after the start of operation, does not decrease significantly from the initial detected temperature, which is the value detected by the heat exchanger temperature sensor at the start of operation, and the difference between the initial detected temperature and the first detected temperature does not exceed a certain value, which may result in an erroneous detection of a refrigerant leak.

[0005] Furthermore, when a heat exchanger temperature sensor is installed in the condenser, if the condenser is operated in an environment where the temperature around the condenser is higher than room temperature, the condenser temperature rises more slowly than when it is at room temperature, even in a normal state where no refrigerant leak has occurred. As a result, the first detected temperature, which is the value detected by the heat exchanger temperature sensor a predetermined time after the start of operation, does not rise significantly from the initial detected temperature, which is the value detected by the heat exchanger temperature sensor at the start of operation, and the difference between the initial detected temperature and the first detected temperature does not exceed a certain value, which may result in an erroneous detection of a refrigerant leak.

[0006] Therefore, there is room for improvement since it is necessary to accurately detect the occurrence of a refrigerant leak regardless of the temperature environment around the evaporator or condenser where the heat exchanger temperature sensor is installed. [Means for solving the problem]

[0007] In order to solve the above problem, claim 1 of the present invention provides a refrigerant circuit in which a compressor, a condenser, a pressure reducing device, and an evaporator are connected in sequence in a ring shape by refrigerant piping; a bypass piping that connects the refrigerant piping located between the compressor and the condenser and the refrigerant piping located between the pressure reducing device and the evaporator; a bypass valve that is installed in the bypass piping and switches between opening and closing the flow of refrigerant in the bypass piping; a heat exchanger temperature sensor that is installed in the evaporator or the condenser; and a refrigerant circuit that drives the compressor when an operation start command is issued and detects the temperature of the refrigerant by the heat exchanger temperature sensor. and a control unit that controls the opening and closing of the bypass valve based on a value, wherein the control unit compares an initial detected temperature, which is the detected value by the heat exchanger temperature sensor immediately after the start of operation, with a first detected temperature, which is the detected value by the heat exchanger temperature sensor after a predetermined time has elapsed since the start of operation, and opens the bypass valve if a predetermined first condition is met, and compares a second detected temperature, which is the detected value by the heat exchanger temperature sensor after a predetermined time has elapsed since the opening of the bypass valve, with the first detected temperature, and stops operation if a predetermined second condition is met.

[0008] In addition, claim 2 is characterized in that the heat exchange temperature sensor is installed in the evaporator, and the control unit determines that the specified first condition is met if the first detected temperature is higher than the initial detected temperature, and determines that the specified second condition is met if the second detected temperature is lower than the first detected temperature.

[0009] In addition, claim 3 is characterized in that the control unit determines that the predetermined second condition is satisfied if the second detected temperature is equal to or lower than a value obtained by adding a predetermined value to the first detected temperature.

[0010] In addition, claim 4 is characterized in that the heat exchange temperature sensor is installed in the condenser, and the control unit determines that the predetermined first condition is met if the first detected temperature is equal to or lower than the initial detected temperature, and determines that the predetermined second condition is met if the second detected temperature is equal to or higher than the first detected temperature.

[0011] In addition, claim 5 is characterized in that the control unit determines that the predetermined second condition is satisfied if the second detected temperature is equal to or greater than a value obtained by subtracting a predetermined value from the first detected temperature. [Effects of the Invention]

[0012] According to this invention, the initial detection temperature, which is the detection value of the heat exchanger temperature sensor immediately after the start of operation, is compared with the first detection temperature, which is the detection value of the heat exchanger temperature sensor after a predetermined time has elapsed since the start of operation, and if a predetermined first condition is met, the bypass valve is opened, and the second detection temperature, which is the detection value of the heat exchanger temperature sensor after a predetermined time has elapsed since the bypass valve was opened, is compared with the first detection temperature, and if a predetermined second condition is met, operation is stopped, so that whether or not a refrigerant leak has occurred can be accurately detected regardless of the ambient temperature of the evaporator or condenser, and operation can be stopped. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a perspective view showing an air conditioning apparatus according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a front cross-sectional view showing the air conditioning apparatus according to the first embodiment. [Figure 3] FIG. 2 is a diagram illustrating a refrigerant circuit of the air conditioner according to the first embodiment. [Figure 4] FIG. 2 is a control block diagram according to the first embodiment. [Figure 5] 4 is a flowchart illustrating refrigerant leakage detection control in the first embodiment. [Figure 6] 4 is a time chart illustrating a change in the heat exchanger temperature sensor during normal operation in the first embodiment. [Figure 7] FIG. 10 is a diagram illustrating a refrigerant circuit of an air conditioner according to the second embodiment. [Figure 8] 10 is a flowchart illustrating refrigerant leakage detection control in the second embodiment. [Figure 9] 10 is a time chart illustrating a change in the heat exchanger temperature sensor during normal operation in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of the present invention will be described below with reference to the accompanying drawings.

[0015] Example 1 1 shows an air conditioner according to embodiment 1. In this embodiment, a description will be given based on a dehumidifier, which is a type of air conditioner. The outer shell of the dehumidifier 1 is made up of a main body case 10. A handle 11 is provided on the top of the main body case 10, and the user can carry the main body case 10 by grasping the handle 11. A louver 12 is provided on the horizontal surface below the handle 11 at the top of the main body case 10, and an outlet 13 from which dehumidified air is blown out is provided below the louver 12. The louver 12 is pivoted at the front-to-rear end on the left end, and has a mechanism that allows the right end to rotate upward and be fixed at a predetermined angle within a predetermined range. The louver 12 can be fixed at a predetermined angle adjusted by the user, allowing air to be blown in a predetermined direction.

[0016] A tank 14 is stored in the lower front part of the main body case 10. A grip part 15 recessed toward the rear is provided at the lower front part of the tank 14, and the user can remove the tank 14 from the main body case 10 by grasping the grip part 15 and pulling it toward the rear.

[0017] An operation unit 20 made up of a plurality of push-type switches is provided on the upper front surface of the main body case 10. The operation unit 20 has a plurality of switches including an operation switch 20a that issues an instruction to start operation. In addition, at the upper rear of the operation unit 20, there is a display unit 21 made up of a plurality of indicator lamps. The display unit 21 has a plurality of indicator lamps including an operation lamp 21a that lights up when the operation switch 20a is operated to indicate the operating state.

[0018] See Figure 2. On the left side of main body case 10 is inlet port 16, which draws indoor air into main body case 10. Also installed inside main body case 10 is blower fan 18, which is axially supported by fan motor 17. When fan motor 17 is driven, blower fan 18 rotates, which guides the indoor air drawn into main body case 10 through inlet port 16 upward and sends it out through air outlet 13 into the room.

[0019] A drain pan 19 is installed inside the main body case 10 below the condenser 32 and the evaporator 34. When the compressor 31 is driven and the refrigerant flows through the refrigerant circuit 30, the temperature of the evaporator 34 drops, and condensation water adheres to the surface of the evaporator 34. The condensation water adhering to the evaporator 34 drips into the drain pan 19, and the dripping condensation water is guided from the drain pan 19 to the tank 14 through a drain hole (not shown). When the amount of condensation water guided to the tank 14 exceeds a certain amount, a water level sensor (not shown) in the tank 14 detects that the tank 14 is full, and the control unit 50 controls the display unit 21 to display a predetermined lamp to notify the full water state. When the user confirms the full water state notification, the user can grasp the handle 15 of the tank 14, remove the tank 14 from the main body case 10, and discard the condensation water in a bathroom or other location.

[0020] 2 and 3, a refrigerant circuit 30 is installed inside the main body case 10, in which a compressor 31 that compresses a refrigerant to a high temperature and high pressure, a condenser 32 that condenses the refrigerant discharged from the compressor 31, a capillary tube 33 that serves as a pressure reducing device that reduces the refrigerant flowing out from the condenser 32 to a low temperature and low pressure, and an evaporator 34 that evaporates the refrigerant flowing out from the capillary tube 33 are sequentially connected by refrigerant piping. The refrigerant circuit 30 also includes a bypass pipe 35 that connects a refrigerant pipe located between the compressor 31 and the condenser 32 with a refrigerant pipe located between the capillary tube 33 and the evaporator 34. A bypass valve 36 is installed in the middle of the bypass pipe 35, and the presence or absence of refrigerant flow can be controlled by opening and closing the valve.

[0021] The evaporator is provided with a heat exchange temperature sensor 40. The heat exchange temperature sensor 40 can detect the temperature of the refrigerant flowing inside the evaporator .

[0022] Please refer to Fig. 4. The dehumidifier 1 includes a control unit 50 in a main body case 10, which is configured by a microcomputer, a storage unit, and an arithmetic unit. When the control unit 50 determines that an operation start command has been issued, it performs normal operation by driving the compressor 31 and the fan motor 17. Furthermore, when the control unit 50 determines that an operation stop command has been issued during normal operation, it stops driving the compressor 31 and the fan motor 17, thereby stopping operation.

[0023] Next, the operation of the dehumidifier 1 will be described.

[0024] When the control unit 50 determines that the operation switch 20a on the operation unit 20 has been operated, it drives the compressor 31 and the fan motor 17 to perform normal operation. By performing normal operation, indoor air around the main body case 10 is taken into the main body case 10 through the intake port 16, and the indoor air passes through the evaporator 34 and the condenser 32 in sequence. As the indoor air passes through the evaporator 34, its temperature drops, and moisture in the air condenses on the surface of the evaporator 34. This reduces the amount of moisture in the indoor air, thereby dehumidifying the room. The cooled indoor air then passes through the condenser 32, where it is heated, and the heated air is blown into the room through the air outlet 13. During normal operation, the bypass valve 36 is closed, and no refrigerant flows through the bypass pipe 35 .

[0025] During normal operation, when the temperature in the room where the main body case 10 is installed is low and the detected value by the heat exchanger temperature sensor 40 falls below a predetermined defrost start temperature at which frost forms on the surface of the evaporator 34, the bypass valve 36 is opened to allow refrigerant to flow through the bypass piping 35, and defrosting operation is performed. By opening the bypass valve 36, refrigerant that has been heated to a high temperature and high pressure by the compressor 31 flows into the evaporator 34 through the bypass piping 35. The high-temperature refrigerant passing through the evaporator 34 can melt the frost that has formed on the evaporator 34. Thereafter, when the detected value by the heat exchanger temperature sensor 40 falls above a predetermined defrost end temperature, the bypass valve 36 is closed to end the defrosting operation.

[0026] Next, a method for detecting the occurrence of refrigerant leakage in the first embodiment will be described with reference to the flowchart of FIG.

[0027] When the control unit 50 determines that the operation switch 20a on the operating unit 20 has been operated and an instruction to start operation has been issued, it stores the initial value T0, which is the initial detected temperature detected by the heat exchange temperature sensor 40, and starts counting the elapsed time (step S101). After storing an initial value T0 and starting counting the elapsed time in step S101, the control unit 50 determines whether the counted value of the elapsed time is equal to or greater than a predetermined time t1 (step S102). If the result of determination in step S102 shows that the elapsed time from the start of operation is equal to or greater than t1, the control unit 50 proceeds to the next step, and if it is less than t1, it repeats step S102.

[0028] If the control unit 50 determines in step S102 that the elapsed time since the start of operation is t1 or more, it stores the detected value T1, which is the first detected temperature detected by the heat exchange temperature sensor 40 (step S103). After storing the detected value T1 in step S103, the control unit 50 compares T0 with T1, and determines whether T1 is equal to or greater than T0 (T1≧T0), which is a predetermined first condition (step S104). If the control unit 50 determines in step S104 that T1 is equal to or greater than T0, it determines that there is a possibility of a refrigerant leak, opens the bypass valve 36, resets the elapsed time counted up to this point, and starts counting the time that has elapsed since the bypass valve 36 was opened (step S105).

[0029] After opening the bypass valve 36 and starting counting the elapsed time in step S105, the control unit 50 determines whether the elapsed time since the bypass valve 36 was opened is equal to or longer than the predetermined time t2 (step S106). If the result of the determination in step S106 is that the elapsed time since the bypass valve 36 was opened is t2 or more, the control unit 50 proceeds to the next step, and if it is less than t2, the control unit 50 repeats the determination in step S106.

[0030] If the control unit 50 determines in step S106 that the elapsed time since the bypass valve 36 was opened is t2 or more, it stores the detection value T2, which is the second detection temperature detected by the heat exchange temperature sensor 40 (step S107). After storing the detected value T2 in step S107, the control unit 50 compares T2 with T1+a, which is T1 plus a predetermined value a, and determines whether T2, which is a predetermined second condition, is equal to or less than T1+a (T1+a≧T2) (step S108). If the control unit 50 determines in step S108 that T2 is equal to or less than T1+a, it generates a predetermined alarm sound from a speaker (not shown) indicating that a refrigerant leak has occurred, and stops driving the compressor 31 and the fan motor 17 to put the system into a stopped operation state (step S109).

[0031] If the control unit 50 determines in step S104 that T1 is less than T0 or in step S108 that T2 is greater than T1+a, it determines that no refrigerant leakage has occurred and that the condition is normal, and continues operation (step S110).

[0032] Next, the relationship between the change in the heat exchanger temperature sensor 40 during normal operation and refrigerant leakage will be described with reference to FIG.

[0033] During normal operation, if T1≧T0 in step S104, the temperature of the evaporator 34, which should drop significantly from the start of operation if there is no refrigerant leakage from the refrigerant circuit 30 and the system is in a normal state, has not dropped, so there is a possibility that a refrigerant leak is occurring from the refrigerant circuit 30. However, even under normal conditions, the temperature around the main body case 10 is lower than room temperature, so the temperature drop of the evaporator 34 within a specified time from the start of operation is small, and T1≧T0 may hold, which may result in a false detection of a refrigerant leak.

[0034] In the first embodiment of the present invention, if T1≧T0 in step S104, the bypass valve 36 is opened in step S105, and it is checked in step S108 whether the relationship T1+a≧T2 holds. In a normal state, the opening of the bypass valve 36 causes high-temperature refrigerant to flow into the evaporator 34, resulting in a significant rise in the temperature of the evaporator 34. If T1+a≧T2, the temperature of the evaporator 34, which should rise significantly, has not risen, and this indicates the possibility of a refrigerant leak from the refrigerant circuit 30.

[0035] That is, in step S104, the presence or absence of refrigerant leakage from the refrigerant circuit 30 is determined based on the temperature change range of the evaporator 34 before and after a predetermined time has elapsed. If the temperature of the evaporator 34 is normal, the direction of refrigerant flow is checked to see if it is decreasing. If the temperature of the evaporator 34 is normal, the direction of refrigerant flow is checked to see if it is increasing. This is advantageous because it allows accurate determination of whether refrigerant leakage has occurred regardless of the temperature environment around the main body case 10.

[0036] In the first embodiment, T2 is compared with the value obtained by adding a predetermined value a to T1 in step S108, but T1 may be compared with T2. If a refrigerant leak occurs in the refrigerant circuit 30, T2 does not rise significantly compared to T1 even if the bypass valve 36 is opened, because high-temperature refrigerant does not flow into the evaporator 34. Therefore, in step S108, it may be determined whether the relationship T1 ≥ T2 holds, and if the relationship T1 ≥ T2 holds, a warning that a refrigerant leak has occurred may be issued and operation may be stopped.

[0037] Next, the effects of the first embodiment will be described.

[0038] The control unit 50 compares an initial detected temperature, which is the value detected by the heat exchanger temperature sensor 40 immediately after the start of operation, with a first detected temperature, which is the value detected by the heat exchanger temperature sensor 40 a predetermined time after the start of operation, and opens the bypass valve 36 if a predetermined first condition is met. The control unit 50 compares a second detected temperature, which is the value detected by the heat exchanger temperature sensor 40 a predetermined time after the opening of the bypass valve 36, with the first detected temperature, and stops operation if a predetermined second condition is met. This makes it possible to accurately detect refrigerant leakage from the refrigerant circuit 30 regardless of the temperature around the main body case 10. Furthermore, this can be implemented without installing additional components such as a room temperature sensor, and does not increase product costs.

[0039] Furthermore, the heat exchanger temperature sensor 40 is installed in the evaporator 34, and the control unit 50 determines that a predetermined first condition is met if the first detected temperature is equal to or higher than the initial detected temperature, and determines that a predetermined second condition is met if the second detected temperature is equal to or lower than the first detected temperature. Refrigerant leakage from the refrigerant circuit 30 can be detected by a simple method of comparing the detected values ​​of the heat exchanger temperature sensor 40 installed in the evaporator 34 before and after a predetermined time has elapsed since the start of normal operation.

[0040] Furthermore, the control unit 50 determines that a predetermined second condition is satisfied if the second detected temperature is equal to or less than the first detected temperature plus a predetermined value. In a normal state where no refrigerant is leaking from the refrigerant circuit 30, opening the bypass valve 36 causes high-temperature refrigerant to flow into the evaporator 34, resulting in a significant increase in the detected value of the heat exchanger temperature sensor 40. Therefore, by checking whether there is a significant increase in temperature after the bypass valve 36 is opened, it is possible to more accurately detect the occurrence of a refrigerant leak from the refrigerant circuit 30.

[0041] <Example 2> Next, a second embodiment of the present invention will be described. Note that a description of the structure and control common to the first embodiment will be omitted.

[0042] 7, the heat exchange temperature sensor 40 is installed in the condenser 32. In the second embodiment, the heat exchange temperature sensor 40 detects the temperature of the condenser 32.

[0043] Next, a method for detecting the occurrence of refrigerant leakage in the second embodiment will be described with reference to the flowchart of FIG.

[0044] When the control unit 50 determines that the operation switch 20a on the operation unit 20 has been operated and an instruction to start operation has been issued, it stores the initial value T0, which is the initial detected temperature detected by the heat exchange temperature sensor 40, and starts counting the elapsed time (step S201). After storing the initial value T0 and starting counting the elapsed time in step S201, the control unit 50 determines whether the counted value of the elapsed time is equal to or greater than a predetermined time t1 (step S202). If the result of determination in step S202 shows that the elapsed time from the start of operation is equal to or greater than t1, the control unit 50 proceeds to the next step, and if it is less than t1, it repeats step S202.

[0045] If the control unit 50 determines in step S202 that the elapsed time since the start of operation is t1 or more, it stores the detected value T1, which is the first detected temperature detected by the heat exchange temperature sensor 40 (step S203). After storing the detected value T1 in step S203, the control unit 50 compares T0 with T1, and determines whether T1 is equal to or less than T0 (T1≦T0), which is a predetermined first condition (step S204). If the control unit 50 determines in step S204 that T1 is equal to or less than T0, it determines that there is a possibility of a refrigerant leak, opens the bypass valve 36, resets the elapsed time counted up to this point, and starts counting the time that has elapsed since the bypass valve 36 was opened (step S205).

[0046] After opening the bypass valve 36 and starting counting the elapsed time in step S205, the control unit 50 determines whether the elapsed time since the bypass valve 36 was opened is equal to or longer than the predetermined time t2 (step S206). If the result of the determination in step S206 is that the time elapsed since the bypass valve 36 was opened is t2 or more, the control unit 50 proceeds to the next step, and if it is less than t2, the control unit 50 repeats the determination in step S206.

[0047] If the control unit 50 determines in step S206 that the elapsed time since the bypass valve 36 was opened is equal to or longer than t2, it stores the detected value T2, which is the second detected temperature detected by the heat exchange temperature sensor 40 (step S207). After storing the detected value T2 in step S207, the control unit 50 compares T2 with T1-a, which is T1 minus a predetermined value a, and determines whether T2, which is a predetermined second condition, is greater than or equal to T1-a (T1-a≦T2) (step S208). If the control unit 50 determines in step S208 that T2 is equal to or greater than T1-a, it issues a predetermined alarm sound from a speaker (not shown) indicating that a refrigerant leak has occurred, and stops driving the compressor 31 and the fan motor 17 to put the system into a stopped operation state (step S209).

[0048] If the control unit 50 determines in step S204 that T1 is greater than T0 or in step S208 that T2 is less than T1-a, it determines that no refrigerant leakage has occurred and that the condition is normal, and continues operation (step S210).

[0049] Next, the relationship between the change in the heat exchanger temperature sensor 40 during normal operation and refrigerant leakage will be described with reference to FIG.

[0050] During normal operation, if T1≦T0 in step S204, the temperature of the condenser 32, which should rise significantly from the start of operation in a normal state where there is no refrigerant leakage from the refrigerant circuit 30, has not risen, which means that there is a possibility that a refrigerant leak is occurring from the refrigerant circuit 30. However, even under normal conditions, the temperature around the main body case 10 is higher than room temperature, so the temperature rise of the condenser 32 within a specified time from the start of operation is small, and T1≦T0 may hold, which may result in a false detection of a refrigerant leak.

[0051] In the second embodiment of the present invention, if T1≦T0 in step S204, the bypass valve 36 is opened in step S205, and it is checked in step S208 whether the relationship T1−a≦T2 holds. In a normal state, the opening of the bypass valve 36 prevents high-temperature refrigerant from flowing into the condenser 32, resulting in a significant drop in the temperature of the condenser 32. If T1−a≦T2, the temperature of the condenser 32, which should drop significantly, has not dropped, indicating the possibility of a refrigerant leak from the refrigerant circuit 30.

[0052] That is, in step S204, the presence or absence of a refrigerant leak from the refrigerant circuit 30 is determined based on the temperature change range of the condenser 32 before and after a predetermined time has elapsed. If the temperature of the condenser 32 is normal, the direction of the refrigerant flow is checked to see if it is rising. If the temperature of the condenser 32 is normal, the direction of the refrigerant flow is checked to see if it is falling. This is advantageous because it allows accurate determination of whether a refrigerant leak has occurred regardless of the temperature environment around the main body case 10.

[0053] In the second embodiment, T2 is compared with the value obtained by subtracting the predetermined value a from T1 in step S208, but T1 may be compared with T2. If a refrigerant leak occurs in the refrigerant circuit 30, T2 does not decrease significantly compared to T1 even if the bypass valve 36 is opened, because high-temperature refrigerant does not flow into the condenser 32. Therefore, in step S208, it may be determined whether the relationship T1≦T2 holds, and if the relationship T1≦T2 holds, a warning that a refrigerant leak has occurred may be issued and operation may be stopped.

[0054] Next, the effects of the second embodiment will be described.

[0055] The control unit 50 compares an initial detected temperature, which is the value detected by the heat exchanger temperature sensor 40 immediately after the start of operation, with a first detected temperature, which is the value detected by the heat exchanger temperature sensor 40 a predetermined time after the start of operation. If a first predetermined condition is met, the control unit 50 opens the bypass valve 36. If a second detected temperature, which is the value detected by the heat exchanger temperature sensor 40 a predetermined time after the opening of the bypass valve 36, is compared with the first detected temperature, the control unit 50 stops operation if a second predetermined condition is met. The heat exchanger temperature sensor 40 is installed in the condenser 32. If the first detected temperature is equal to or lower than the initial detected temperature, the control unit 50 determines that the first predetermined condition is met. If the second detected temperature is equal to or higher than the first detected temperature, the control unit 50 determines that the second predetermined condition is met. Refrigerant leakage from the refrigerant circuit 30 can be detected by the simple method of comparing the detected values ​​of the heat exchanger temperature sensor 40 installed in the condenser 32 before and after the predetermined time has elapsed since the start of normal operation.

[0056] Furthermore, the control unit 50 determines that a predetermined second condition is satisfied if the second detected temperature is equal to or greater than the first detected temperature minus a predetermined value. In a normal state where no refrigerant is leaking from the refrigerant circuit 30, opening the bypass valve 36 prevents high-temperature refrigerant from flowing into the condenser 32, resulting in a significant drop in the detected value of the heat exchanger temperature sensor 40. Therefore, by checking whether there is a significant drop in temperature after the bypass valve 36 is opened, it is possible to more accurately detect the occurrence of a refrigerant leak from the refrigerant circuit 30.

[0057] It should be noted that the present invention is not limited to the examples provided that the functions and effects of the present invention are achieved.

[0058] For example, in each of the embodiments described above, the capillary tube 33 is used as the pressure reducing device, but this is not limiting. For example, an electronic expansion valve with a variable opening may be used as the pressure reducing device.

[0059] Furthermore, in the described embodiments, a dehumidifier 1, which is a type of air conditioner, has been used for explanation, but the present invention is not limited to this. For example, the present invention can also be applied to a separate-type air conditioner in which an indoor unit installed indoors and an outdoor unit installed outdoors are connected by a refrigerant pipe. In an air conditioner equipped with a refrigerant circuit 30, if a refrigerant leak from the refrigerant circuit 30 is detected by comparing the detected values ​​by the heat exchanger temperature sensor 40 before and after a predetermined time has elapsed when the bypass valve 36 is closed with those by the heat exchanger temperature sensor 40 before and after a predetermined time has elapsed when the bypass valve 36 is open, this falls within the scope of the present invention. [Explanation of symbols]

[0060] 1. Dehumidifier (air conditioning unit) 30 Refrigerant circuit 31 Compressor 32 Condenser 33 Capillary tube (pressure reducing device) 34 Evaporator 35 Bypass piping 36 Bypass valve 40 Heat exchanger temperature sensor 50 control section

Claims

1. a refrigerant circuit in which a compressor, a condenser, a pressure reducing device, and an evaporator are connected in sequence in a ring shape by refrigerant piping; a bypass pipe connecting the refrigerant pipe located between the compressor and the condenser and the refrigerant pipe located between the pressure reducing device and the evaporator; a bypass valve installed in the bypass pipe for switching between opening and closing the flow of refrigerant in the bypass pipe; a heat exchange temperature sensor installed in the evaporator or the condenser; a control unit that drives the compressor when an operation start command is issued and controls opening and closing of the bypass valve based on a detection value of the heat exchanger temperature sensor, The control unit an initial detected temperature, which is a detected value by the heat exchanger temperature sensor immediately after the start of operation, is compared with a first detected temperature, which is a detected value by the heat exchanger temperature sensor after a predetermined time has elapsed since the start of operation, and if a predetermined first condition is satisfied, the bypass valve is opened; An air conditioning apparatus characterized by comparing a second detected temperature, which is the detected value of the heat exchanger temperature sensor after a predetermined time has elapsed since the bypass valve was opened, with the first detected temperature, and stopping operation if a predetermined second condition is met.

2. The heat exchange temperature sensor is installed in the evaporator, The control unit If the first detected temperature is equal to or higher than the initial detected temperature, it is determined that the predetermined first condition is satisfied; 2. The air conditioner according to claim 1, wherein if the second detected temperature is equal to or lower than the first detected temperature, it is determined that the predetermined second condition is satisfied.

3. The control unit 3. The air conditioner according to claim 2, wherein if the second detected temperature is equal to or lower than a value obtained by adding a predetermined value to the first detected temperature, it is determined that the predetermined second condition is satisfied.

4. the heat exchange temperature sensor is installed in the condenser; The control unit If the first detected temperature is equal to or lower than the initial detected temperature, it is determined that the predetermined first condition is satisfied; 2. The air conditioner according to claim 1, wherein if the second detected temperature is equal to or higher than the first detected temperature, it is determined that the predetermined second condition is satisfied.

5. The control unit 5. The air conditioner according to claim 4, wherein if the second detected temperature is equal to or greater than a value obtained by subtracting a predetermined value from the first detected temperature, it is determined that the predetermined second condition is satisfied.

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