Air conditioner and control method for air conditioner

Abstract

To provide an air conditioner that is less likely to cause hunting and a control method for the air conditioner.SOLUTION: An air conditioner includes: a refrigerant circuit configured by connecting a compressor 11, an outdoor side heat exchanger, an expansion valve 14 and an indoor side heat exchanger; temperature detection means 26 detecting a temperature of the indoor side heat exchanger; and control means 100 controlling the refrigerant circuit. The control means 100 counts frequency of transfer of the temperature detected by the temperature detection means 26 during a dehumidification operation from a state higher than a first temperature to a state equal to or lower than the first temperature, and temporarily stops the dehumidification operation on the basis of the frequency. Alternatively, the control means counts frequency of transfer from the state higher than the first temperature to the state equal to or lower than the first temperature and then, transfer to the state higher than the first temperature, and temporarily stops the dehumidification operation on the basis of the frequency.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an air conditioner and a method for controlling an air conditioner. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there have been air conditioners that perform dehumidifying operation by using a part of an indoor heat exchanger as an evaporation zone and another part as a superheat zone. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 09-014727 Summary of the Invention [Problem to be solved by the invention]

[0004] In such an air conditioner, hunting can occur during dehumidification operation.

[0005] For example, if the outlet temperature of the evaporative zone of the indoor heat exchanger does not drop sufficiently due to a small indoor load, the expansion valve is controlled to decrease its opening in order to lower the outlet temperature. This causes the inlet temperature of the indoor heat exchanger to drop, so the expansion valve is controlled to increase its opening in order to raise the inlet temperature. This causes the outlet temperature of the evaporative zone to rise again, so the expansion valve is controlled to decrease its opening again in order to lower the outlet temperature.

[0006] If hunting occurs, in which the expansion valve is frequently opened and closed, there is a risk that the indoor heat exchanger will freeze or that the evaporation and superheating regions will not be maintained within the intended ranges. In view of the above-mentioned problems, an object of the present disclosure is to provide an air conditioner in which hunting is less likely to occur. [Means for solving the problem]

[0007] An air conditioner according to one aspect of the present disclosure comprises a refrigerant circuit configured by connecting a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger, a temperature detection means for detecting the temperature of the indoor heat exchanger, and a control means for controlling the refrigerant circuit, wherein the control means counts the number of times that the temperature detected by the temperature detection means during dehumidification operation transitions from a state higher than a first temperature to a state lower than the first temperature, or the number of times that the temperature transitions from a state higher than the first temperature to a state lower than the first temperature and then again transitions to a state higher than the first temperature, and temporarily suspends the dehumidification operation based on the number of times.

[0008] A control method for an air conditioner according to one aspect of the present disclosure is a control method for an air conditioner equipped with a refrigerant circuit configured by connecting a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger, a temperature detection means for detecting the temperature of the indoor heat exchanger, and a control means for controlling the refrigerant circuit, wherein the control means counts the number of times that the temperature detected by the temperature detection means during dehumidification operation transitions from a state higher than a first temperature to a state lower than the first temperature, or the number of times that the temperature transitions from a state higher than the first temperature to a state lower than the first temperature and then again transitions to a state higher than the first temperature, and temporarily suspends the dehumidification operation based on the number of times. [Effects of the Invention]

[0009] An air conditioner and a control method for an air conditioner according to one aspect of the present disclosure count the number of times the temperature detected by a temperature detection unit transitions from a state exceeding a first temperature to a state equal to or lower than the first temperature, and temporarily suspends the dehumidifying operation based on the number of times. Alternatively, the air conditioner counts the number of times the temperature detected by a temperature detection unit transitions from a state exceeding the first temperature to a state equal to or lower than the first temperature and then transitions back to a state exceeding the first temperature, and temporarily suspends the dehumidifying operation based on the number of times. Therefore, hunting is less likely to occur. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing an air conditioner according to an embodiment of the present invention; [Figure 2] Cross-sectional view showing the indoor unit [Figure 3] Block diagram showing the air control means and the devices connected thereto. [Figure 4] Schematic side view showing the evaporation zone and superheat zone of the indoor heat exchanger [Figure 5] Flowchart showing the control process for dehumidification operation [Figure 6] Flowchart showing a process for determining expansion valve control conditions [Figure 7] Target inlet temperature table [Figure 8] Target outlet temperature table [Figure 9] Flowchart showing hunting determination processing [Figure 10] FIG. 10 is a diagram showing an example of a change in outlet temperature over time during dehumidification operation. [Figure 11] Flowchart showing hunting determination processing [Figure 12] Flowchart showing the process of temporarily suspending the dehumidification operation DETAILED DESCRIPTION OF THE INVENTION

[0011] The air conditioner according to the present disclosure is an air conditioning facility that controls the temperature, humidity, air purification, etc., of a room, and is, for example, a home air conditioner.

[0012] <Air conditioner configuration> (Schematic configuration) Fig. 1 is a schematic diagram showing the configuration of an air conditioner according to the present embodiment. As shown in Fig. 1, the air conditioner 1 according to the present embodiment includes an outdoor unit 10 and an indoor unit 20.

[0013] The outdoor unit 10 and the indoor unit 20 are connected by piping 2. Specifically, the compressor 11, four-way valve 12, outdoor heat exchanger 13, and expansion valve 14 provided in the outdoor unit 10, and the indoor heat exchanger 21 provided in the indoor unit 20 are connected by piping 2. The compressor 11, four-way valve 12, outdoor heat exchanger 13, expansion valve 14, indoor heat exchanger 21, and piping 2 form a refrigeration circuit. Note that various valves (not shown) other than the four-way valve 12 and the expansion valve 14, a strainer (not shown), and the like are also connected to the piping 2.

[0014] (Outdoor unit configuration) The outdoor unit 10 includes a compressor 11, a four-way valve 12, an outdoor heat exchanger 13, an expansion valve 14, an outdoor blower 15, outdoor control means 101, an accumulator (not shown), and the like.

[0015] The compressor 11 compresses the refrigerant in the refrigeration circuit to a high temperature and high pressure.

[0016] The four-way valve 12 switches the refrigerant flow path so that the refrigerant in the refrigeration circuit is sent to the condenser. Specifically, during cooling operation or dehumidification operation, the four-way valve 12 switches the refrigerant flow path so that the refrigerant is sent to the outdoor heat exchanger 13, which functions as a condenser. On the other hand, during heating operation, the four-way valve 12 switches the refrigerant flow path so that the refrigerant is sent to the indoor heat exchanger 21, which functions as a condenser.

[0017] The outdoor heat exchanger 13 exchanges heat between the refrigerant in the refrigeration circuit and the air sent into the outdoor heat exchanger 13 .

[0018] The expansion valve 14 reduces the pressure of the refrigerant in the refrigeration circuit to expand it and make it low-temperature and low-pressure. During cooling or dehumidifying operation, the low-temperature and low-pressure refrigerant is sent from the expansion valve 14 to the indoor heat exchanger 21, which functions as an evaporator. During heating operation, the low-temperature and low-pressure refrigerant is sent to the outdoor heat exchanger 13, which functions as an evaporator.

[0019] The outdoor blower 15 is equipped with a propeller fan (not shown), and the rotation of the propeller fan generates a flow of air that passes through the outdoor heat exchanger 13. This improves the efficiency of heat exchange in the outdoor heat exchanger 13.

[0020] The outdoor control means 101 controls the operation of the outdoor unit 10. Details will be described later.

[0021] (Indoor unit configuration) Fig. 2 is a cross-sectional view showing the indoor unit. As shown in Fig. 1 and Fig. 2, the indoor unit 20 includes an indoor heat exchanger 21, an indoor blower 22, an inlet temperature detection means 23, a humidity detection means 24, an inlet temperature detection means 25, an outlet temperature detection means 26, a filter 27, upper and lower blades 28, an indoor control means 102, and a housing 29 that houses them.

[0022] 2, an intake port 29a is provided on the top surface of the housing 29 for drawing air into the housing 29. In addition, an exhaust port 29b is provided on the bottom surface of the housing 29 for expelling the air inside the housing 29 to the outside of the housing 29.

[0023] The indoor heat exchanger 21 includes three main heat exchangers 21a to 21c and two auxiliary heat exchangers 21d and 21e.

[0024] The main heat exchangers 21a to 21c are arranged between the indoor blower 22 and the filter 27 in a generally inverted V shape so as to surround the indoor blower 22.

[0025] The auxiliary heat exchangers 21d and 21e are arranged between the indoor blower 22 and the filter 27, and further outward than the main heat exchangers 21a to 21c with respect to the indoor blower 22. Specifically, the auxiliary heat exchanger 21d is arranged between the main heat exchanger 21a and the filter 27, and the auxiliary heat exchanger 21e is arranged between the main heat exchanger 21b and the filter 27.

[0026] The main heat exchangers 21a to 21c and the auxiliary heat exchangers 21d and 21e each have a structure in which fins (not shown) are attached to a pipe (not shown). The main heat exchangers 21a to 21c and the auxiliary heat exchangers 21d and 21e exchange heat between the refrigerant flowing through each pipe and the air sent to the indoor heat exchanger 21.

[0027] The indoor blower 22 generates air flows 31 and 32 that are sent to the indoor heat exchanger 21. Specifically, the air flows 31 and 32 are generated by sucking air through the air inlet 29a, passing through the filter 27, the indoor heat exchanger 21, and the indoor blower 22, and being discharged from the air outlet 29b. This improves the efficiency of heat exchange in the indoor heat exchanger 21.

[0028] The auxiliary heat exchangers 21d and 21e are arranged upwind of the main heat exchangers 21a to 21c in the air flows 31 and 32. Specifically, the auxiliary heat exchanger 21d is arranged upwind of the main heat exchanger 21a in the air flow 31, and the auxiliary heat exchanger 21e is arranged upwind of the main heat exchanger 21b in the air flow 32.

[0029] Returning to Fig. 1, air inlet temperature detection means 23 is disposed near air inlet 29a inside housing 29. Air inlet temperature detection means 23 detects the temperature of air that has been drawn into housing 29 through air inlet 29a and before being heat exchanged by indoor heat exchanger 21. Hereinafter, the temperature detected by air inlet temperature detection means 23 will be referred to as the "air inlet temperature."

[0030] Humidity detection means 24 is disposed near air inlet 29a inside housing 29. Humidity detection means 24 detects the humidity of air that has been drawn into housing 29 through air inlet 29a and before heat exchange by indoor heat exchanger 21.

[0031] The inlet temperature detecting means 25 detects the temperature near the inlet of the refrigerant in the evaporation region (described later) of the indoor heat exchanger 21. Hereinafter, the temperature detected by the inlet temperature detecting means 25 will be referred to as "inlet temperature T1."

[0032] The outlet temperature detection means 26 detects the temperature near the outlet of the refrigerant in the evaporation region of the indoor heat exchanger 21. Hereinafter, the temperature detected by the outlet temperature detection means 26 will be referred to as "outlet temperature T2."

[0033] Filter 27 is disposed in the vicinity of suction port 29a in housing 29 so as to close suction port 29a, and removes dust and dirt from the air drawn into housing 29 through suction port 29a.

[0034] Upper and lower blades 28 are rotatably provided near outlet 29b of housing 29, and adjust the direction of air discharged from outlet 29b when air conditioner 1 is in operation. Furthermore, upper and lower blades 28 close outlet 29b when air conditioner 1 is not in operation.

[0035] The indoor control means 102 controls the operation of the indoor unit 20. Details will be described later.

[0036] (Configuration of air control means) 1, the control means 100 is made up of the outdoor control means 101 of the outdoor unit 10 and the indoor control means 102 of the indoor unit 20. The operation of the air conditioner 1 is controlled by the control means 100.

[0037] Fig. 3 is a block diagram showing the air control means and devices connected thereto. As shown in Fig. 3, the control means 100 includes an acquisition unit 103, a memory unit 104, a calculation unit 105, and a drive unit 106. The calculation unit 105 is connected to each of the acquisition unit 103, the memory unit 104, and the drive unit 106.

[0038] The acquisition unit 103 is connected to the suction port temperature detection means 23, the humidity detection means 24, the inlet temperature detection means 25, and the outlet temperature detection means 26. The acquisition unit 103 acquires the suction port temperature detected by the suction port temperature detection means 23, the humidity detected by the humidity detection means 24, the inlet temperature T1 detected by the inlet temperature detection means 25, and the outlet temperature T2 detected by the outlet temperature detection means 26.

[0039] The storage unit 104 stores setting values ​​that are used by the calculation unit 105 to create a temperature table.

[0040] The calculation unit 105 receives information from the acquisition unit 103 and the storage unit 104, and performs calculations based on the information.

[0041] The drive unit 106 is connected to the compressor 11 and the expansion valve 14. Based on the result of the calculation by the calculation unit 105, the drive unit 106 transmits an instruction signal to the compressor 11 and the expansion valve 14 to drive the compressor 11 and the expansion valve 14.

[0042] <Air conditioner operation> (Refrigerant flow in the refrigeration circuit) The flow of refrigerant in the refrigeration circuit during cooling operation or dehumidification operation will be described.

[0043] During cooling or dehumidifying operation, the gaseous refrigerant in the refrigeration circuit is compressed by the compressor 11 to a high temperature and high pressure. The high-temperature, high-pressure refrigerant is sent to the outdoor heat exchanger 13 via the four-way valve 12. The refrigerant sent to the outdoor heat exchanger 13 exchanges heat with the air passing through the outdoor heat exchanger 13. This heat exchange causes the gaseous refrigerant to condense and change into a liquid refrigerant. The liquid refrigerant passes through the expansion valve 14 to a low temperature and low pressure, becoming a gas-liquid two-phase refrigerant before being sent to the indoor heat exchanger 21.

[0044] The gas-liquid two-phase refrigerant sent to the indoor heat exchanger 21 exchanges heat with the air passing through the indoor heat exchanger 21. This heat exchange changes the gas-liquid two-phase refrigerant into a gaseous state. The gaseous refrigerant is sent back to the compressor 11.

[0045] As described above, during cooling or dehumidifying operation, the refrigerant circulates through the refrigeration circuit in the following order: compressor 11, four-way valve 12, outdoor heat exchanger 13, expansion valve 14, and indoor heat exchanger 21. On the other hand, during heating operation, the refrigerant circulates through the refrigeration circuit in the opposite direction to that during cooling or dehumidifying operation.

[0046] (evaporation and superheating zones of the indoor heat exchanger) The air conditioner 1 can selectively perform a dehumidifying operation in which a portion of the indoor heat exchanger 21 serves as an evaporation region, or a dehumidifying operation in which the entire indoor heat exchanger 21 serves as an evaporation region. The user can select which dehumidifying operation to perform by operating a remote controller (not shown) or the like. The following describes in detail the indoor heat exchanger 21 during dehumidifying operation in which a portion of the indoor heat exchanger 21 serves as an evaporation region. The air conditioner 1 may be configured to perform only a dehumidifying operation in which a portion of the indoor heat exchanger 21 serves as an evaporation region, but not a dehumidifying operation in which the entire indoor heat exchanger 21 serves as an evaporation region, or may be configured to perform a dehumidifying operation in which a portion of the indoor heat exchanger 21 serves as an evaporation region when certain conditions (e.g., a predetermined indoor and outdoor temperature, a predetermined indoor humidity, and the compressor 11 has been operating for a predetermined time) are met during cooling operation or a dehumidifying operation in which the entire indoor heat exchanger 21 serves as an evaporation region.

[0047] FIG. 4 is a schematic side view showing the evaporation region and superheat region of the indoor heat exchanger. During dehumidifying operation, the indoor heat exchanger 21 is divided into an evaporation region and a superheat region, for example, as shown in FIG. 4. In FIG. 4, the part with an "x" inside a circle is the evaporation region, and the part with a "o" inside a circle is the superheat region. That is, the entire main heat exchanger 21a is in the superheat region. Each of the main heat exchangers 21b and 21c has a part that is the evaporation region and the other part that is the superheat region. Each of the auxiliary heat exchangers 21d and 21e is in the entire evaporation region.

[0048] The main heat exchangers 21a to 21c and the auxiliary heat exchangers 21d and 21e are connected by pipes 50 to 60. Specifically, the expansion valve 14 (not shown in FIG. 4) is connected to the auxiliary heat exchanger 21d by pipe 50. The auxiliary heat exchanger 21d is connected to the auxiliary heat exchanger 21e by pipe 51. The auxiliary heat exchanger 21e is connected to the evaporation area of ​​the main heat exchanger 21b by pipe 52. The evaporation area of ​​the main heat exchanger 21b is connected to the evaporation area of ​​the main heat exchanger 21c by pipe 53. The evaporation area of ​​the indoor heat exchanger 21 is composed of the auxiliary heat exchanger 21d, the auxiliary heat exchanger 21e, the evaporation area of ​​the main heat exchanger 21b, and the evaporation area of ​​the main heat exchanger 21c.

[0049] The evaporation zone of the main heat exchanger 21c is connected to the main heat exchanger 21a by pipes 54 and 55. The main heat exchanger 21a is connected to a part of the superheat zone of the main heat exchanger 21b by pipe 56. A part of the superheat zone of the main heat exchanger 21b is connected to the compressor 11 (not shown in FIG. 4) by pipe 57. The main heat exchanger 21a and a part of the superheat zone of the main heat exchanger 21b form a first superheat zone of the indoor heat exchanger 21.

[0050] The evaporation zone of the main heat exchanger 21c is also connected to the other part of the superheat zone of the main heat exchanger 21b by pipes 54 and 58. The other part of the superheat zone of the main heat exchanger 21b is connected to the superheat zone of the main heat exchanger 21c by pipe 59. The superheat zone of the main heat exchanger 21c is connected to the compressor 11 (not shown in FIG. 4) by pipe 60. The other part of the superheat zone of the main heat exchanger 21b and the superheat zone of the main heat exchanger 21c form a second superheat zone of the indoor heat exchanger 21.

[0051] The evaporation zone and superheat zone described above are, strictly speaking, regions that are intended to be evaporation zones and superheat zones. In reality, the evaporation zone and superheat zone may be narrower or wider than intended. More specifically, the positions of the evaporation zone inlet and the superheat zone outlet do not change, but the positions of the evaporation zone outlet and the superheat zone inlet may change. That is, the evaporation zone and superheat zone have a relationship in which the narrower the evaporation zone, the wider the superheat zone, and vice versa. Therefore, in order to maintain the evaporation zone and superheat zone within the intended ranges, the control means 100 controls the opening and closing of the expansion valve 14. This will be described in detail later.

[0052] The refrigerant sent from the expansion valve 14 first flows into the evaporation zone of the indoor heat exchanger 21, then branches and passes through the first and second superheat zones, flows out of those superheat zones, and is sent to the compressor 11. Specifically, the refrigerant sent from the expansion valve 14 flows into the auxiliary heat exchanger 21d from pipe 50, passes through pipe 51, auxiliary heat exchanger 21e, pipe 52, the evaporation zone of the main heat exchanger 21b, pipe 53, and the evaporation zone of the main heat exchanger 21c. Next, pipe 54 branches into pipe 55 and pipe 58, so the refrigerant passes through a route consisting of the main heat exchanger 21a, pipe 56, and part of the superheat zone of the main heat exchanger 21b, or a route consisting of the other part of the superheat zone of the main heat exchanger 21b, pipe 59, and the superheat zone of the main heat exchanger 21c, flows out from pipe 57 or pipe 60, and is sent to the compressor 11.

[0053] The inlet temperature detection means 25 is provided near the inlet of the evaporation zone of the indoor heat exchanger 21. More specifically, the inlet temperature detection means 25 is provided near the auxiliary heat exchanger 21d. As described above, the evaporation zone of the indoor heat exchanger 21 is made up of the auxiliary heat exchanger 21d, the auxiliary heat exchanger 21e, the evaporation zone of the main heat exchanger 21b, and the evaporation zone of the main heat exchanger 21c, and the auxiliary heat exchanger 21d is the most upstream of these. Therefore, the piping 50 connected to the most upstream auxiliary heat exchanger 21d corresponds to the vicinity of the inlet of the evaporation zone. Therefore, the inlet temperature detection means 25 is provided on the piping 50.

[0054] In this way, the inlet temperature detection means 25 is provided on the pipe 50 through which the refrigerant flows into the evaporation zone, so it is possible to accurately measure the temperature near the inlet of the evaporation zone of the indoor heat exchanger 21. Therefore, it is possible to efficiently control the temperature when performing control to prevent clogging due to freezing of the indoor heat exchanger 21 or when performing defreezing operation.

[0055] The outlet temperature detection means 26 is provided near the outlet of the evaporation zone of the indoor heat exchanger 21. To repeat, the evaporation zone of the indoor heat exchanger 21 is made up of the auxiliary heat exchanger 21d, the auxiliary heat exchanger 21e, the evaporation zone of the main heat exchanger 21b, and the evaporation zone of the main heat exchanger 21c, and the most downstream of these is the evaporation zone of the main heat exchanger 21c. Therefore, the pipe 54 connected to the evaporation zone of the most downstream main heat exchanger 21c corresponds to the vicinity of the outlet of the evaporation zone. Therefore, the outlet temperature detection means 26 is provided on the pipe 54.

[0056] Strictly speaking, the vicinity of the outlet of the evaporation zone where the outlet temperature detection means 26 is provided means the vicinity of the outlet of the zone intended to be the evaporation zone. As described above, the evaporation zone may narrow or widen during dehumidification operation. Furthermore, the position of the outlet of the evaporation zone may fluctuate during dehumidification operation. Therefore, the outlet temperature detection means 26 is provided near the outlet of the zone intended to be the evaporation zone. Specifically, the vicinity of the outlet corresponds to, for example, the evaporation zone of the main heat exchanger 21c, the pipe 54, the pipe 55, and the pipe 58, and in this embodiment, the outlet temperature detection means 26 is provided on the pipe 54.

[0057] In this way, the outlet temperature detection means 26 is provided on the pipe 54 through which the refrigerant flows out from the evaporation area, so it is possible to accurately measure the temperature near the outlet of the evaporation area of ​​the indoor heat exchanger 21. Therefore, when the temperature near the outlet of the evaporation area of ​​the indoor heat exchanger 21 detected by the outlet temperature detection means 26 and the suction port temperature detected by the suction port temperature detection means 23 are substantially the same, it can be detected that evaporation has ended.

[0058] The locations where the inlet temperature detection means 25 and the outlet temperature detection means 26 are provided are not limited to those described above. The inlet temperature detection means 25 may be provided upstream of the pipe 50, that is, near the expansion valve 14. This arrangement makes it possible to detect the temperature at which the refrigerant temperature drops to its lowest. Furthermore, the inlet temperature detection means 25 may be provided in a pipe in the evaporation region, for example, in the pipe 51, the pipe 52, or the pipe 53.

[0059] The outlet temperature detection means 26 may be provided in the pipes 55 and 58 branching off from the pipe 54. This arrangement enables the outlet temperature detection means 26 to detect the temperature of the pipes through which the branched refrigerant flows. Furthermore, the outlet temperature detection means 26 may be provided downstream of the pipes 55 and 58, that is, in the vicinity of the main heat exchanger 21a and / or the main heat exchanger 21b. This arrangement enables more accurate detection of the temperature at which the main heat exchanger 21a and / or the main heat exchanger 21b reaches an overheated range.

[0060] <Air conditioner control method> (Dehumidification operation control process) Fig. 5 is a flowchart showing the control process of the dehumidifying operation. As shown in Fig. 5, when the dehumidifying operation is started by, for example, the user pressing the first dehumidifying operation button, the control means 100 performs a process of determining the expansion valve control conditions (step S101). The details of the process of determining the expansion valve control conditions will be described later.

[0061] When the process of determining the expansion valve control condition is completed, the control means 100 determines whether the inlet temperature T1 is equal to or higher than an upper limit temperature (third temperature) (step S102). The upper limit temperature is a temperature determined in the process of determining the expansion valve control condition, which will be described later.

[0062] If the inlet temperature T1 is equal to or higher than the upper limit temperature ("Yes" in step S102), the control means 100 sends an instruction signal to the drive unit 106 to decrease the opening of the expansion valve 14, and the drive unit 106 decreases the opening of the expansion valve 14 (step S107).

[0063] When the opening degree of the expansion valve 14 decreases, the control means 100 determines whether the dehumidifying operation has stopped (S109), and if the dehumidifying operation has stopped ("Yes" in step S109), ends the control process for the dehumidifying operation. If the dehumidifying operation has not stopped ("No" in step S109), the control means 100 performs the process of determining the expansion valve control condition again (step S101).

[0064] Returning to step S102, if the inlet temperature T1 is not equal to or higher than the upper limit temperature (third temperature) ("No" in step S102), the control means 100 determines whether the heating temperature T3 is equal to or higher than the upper limit temperature (step S103). If the heating temperature T3 is equal to or higher than the upper limit temperature ("Yes" in step S103), the control means 100 sends an instruction signal to the drive unit 106 to decrease the opening of the expansion valve 14, and the drive unit 106 decreases the opening of the expansion valve 14 (step S107). The processing after the opening of the expansion valve 14 is decreased is as described above.

[0065] Returning to step S103, if the heating temperature T3 is not equal to or higher than the upper limit temperature ("No" in step S103), the control means 100 determines whether the inlet temperature T1 is equal to or lower than a lower limit temperature (second temperature) (step S104). The lower limit temperature is a temperature determined in a process for determining expansion valve control conditions, which will be described later.

[0066] If the inlet temperature T1 is equal to or lower than the lower limit temperature ("Yes" in step S104), the control means 100 sends an instruction signal to the drive unit 106 to increase the opening degree of the expansion valve 14, and the drive unit 106 increases the opening degree of the expansion valve 14 (step S108).

[0067] When the opening degree of the expansion valve 14 increases, the control means 100 determines whether the dehumidifying operation is stopped (S109), and if the dehumidifying operation is stopped ("Yes" in step S109), ends the control process for the dehumidifying operation. If the dehumidifying operation is not stopped ("Yes" in step S109), the process for determining the expansion valve control condition is performed again (step S101).

[0068] On the other hand, returning to step S104, if the inlet temperature T1 is not equal to or lower than the lower limit temperature (second temperature) ("No" in step S104), the control means 100 determines whether the heating temperature T3 is equal to or lower than the lower limit temperature (step S105). If the heating temperature T3 is equal to or lower than the lower limit temperature ("Yes" in step S105), the control means 100 sends an instruction signal to the drive unit 106 to increase the opening of the expansion valve 14, and the drive unit 106 increases the opening of the expansion valve 14 (step S108). The processing after the opening of the expansion valve 14 has increased is as described above.

[0069] Returning to step S105, if the heating temperature T3 is not equal to or lower than the lower limit temperature ("No" in step S105), the control means 100 determines that the inlet temperature T1 and the heating temperature T3 are within the stable region, and maintains the opening of the expansion valve 14 (step S106). Furthermore, the control means 100 determines whether the dehumidifying operation has stopped (S109), and if the dehumidifying operation has stopped ("Yes" in step S109), ends the control processing for the dehumidifying operation. If the dehumidifying operation has not stopped ("Yes" in step S109), the process of determining the expansion valve control conditions is performed again (step S101).

[0070] As described above, when at least one of the inlet temperature T1 and the heating temperature T3 is equal to or higher than the upper limit temperature, the aperture of the expansion valve 14 is decreased, and when at least one of the inlet temperature T1 and the heating temperature T3 is equal to or lower than the lower limit temperature, the aperture of the expansion valve 14 is increased. Otherwise, the aperture of the expansion valve 14 is maintained.

[0071] (Expansion valve control condition determination process) Fig. 6 is a flowchart showing the process of determining the expansion valve control condition. As shown in Fig. 6, in the process of determining the expansion valve control condition, acquisition unit 103 acquires information about the suction port temperature detected by suction port temperature detection means 23 (suction port temperature information) from suction port temperature detection means 23 (step S201). Acquisition unit 103 also acquires information about the humidity detected by humidity detection means 24 (humidity information) from humidity detection means 24 (step S202). Note that acquisition of the suction port temperature information or the humidity information may be either first, or both may be acquired simultaneously.

[0072] Next, the calculation unit 105 determines the dew point temperature based on the air inlet temperature information and humidity information acquired by the acquisition unit 103 and the set value stored in advance in the storage unit 104 (step S203).

[0073] Next, the calculation unit 105 determines a target inlet temperature table based on the dew point temperature and information in the storage unit 104 (step S204). Here, the target inlet temperature table is a temperature table whose goal is to control the opening of the expansion valve 14 so that the inlet temperature T1 detected by the inlet temperature detection means 25 falls within a stable region. A method for determining the target inlet temperature table will be described in detail later.

[0074] Next, calculation unit 105 determines a target outlet temperature table based on the dew point temperature and information in storage unit 104 (step S205). Here, the target outlet temperature table is a temperature table with the goal of controlling the opening of expansion valve 14 so that the temperature (hereinafter referred to as "heating temperature T3") obtained by subtracting outlet temperature T2 detected by outlet temperature detection means 26 from the suction port temperature falls within the stable region. A method for determining the target outlet temperature table will be described in detail later.

[0075] It should be noted that the determination of the target inlet temperature table and the determination of the target outlet temperature table may be either first or both may be determined simultaneously.

[0076] (Target inlet temperature table) 7 is a diagram showing a target inlet temperature table. As shown in FIG. 7, in this embodiment, the target inlet temperature table determines five regions in descending order of temperature: opening degree decreasing region A, opening degree decreasing region B, stable region, opening degree increasing region B, and opening degree increasing region A. The opening degree increasing region A and opening degree increasing region B are regions in which the opening of expansion valve 14 is increased, and the opening degree decreasing region A and opening degree decreasing region B are regions in which the opening of expansion valve 14 is decreased. Here, when the opening of expansion valve 14 in the stable region is used as a reference, the increase in opening is in the order of opening degree increasing region A > opening degree increasing region B, and the decrease in opening is in the order of opening degree decreasing region A > opening degree decreasing region B.

[0077] By determining the range in this manner, even if the inlet temperature T1 is in a temperature range (above a third temperature) higher than the stable region such as the opening decrease region A and the opening decrease region B, the opening of the expansion valve 14 can be reduced to lower the inlet temperature T1 to the stable region, and the indoor air passing through the indoor heat exchanger 21 can be lowered to a temperature below the dew point temperature, thereby enabling dehumidification. Furthermore, even if the inlet temperature T1 is in a temperature range (below a second temperature) lower than the stable region such as the opening increase region A and the opening increase region B, the opening of the expansion valve 14 can be increased to suppress freezing near the inlet of the indoor heat exchanger 21, allowing stable dehumidification without clogging due to freezing.

[0078] These regions are T I1 , T I2 , T I3 , T I4 , T I1 +1, T I2 +1, T I3 +1, T I4 It is divided into eight temperatures, T I1 , T I2 , T I1 +1, T I2 +1 indicates the upper limit temperature (third temperature) that is the criterion for determining whether to reduce the opening of the expansion valve 14 in the control process for the dehumidification operation. I3 , T I4 , T I3 +1, T I4+1 indicates a lower limit temperature (second temperature) that is a criterion for determining whether to increase the opening of the expansion valve 14 in the control process for the dehumidifying operation.

[0079] Furthermore, to explain the eight temperatures from another angle, T I1 , T I2 , T I3 , T I4 indicates the boundary temperature when the inlet temperature T1 decreases, and T I1 +1, T I2 +1, T I3 +1, T I4 +1 indicates the boundary temperature when the inlet temperature T1 is rising. The boundary temperature when the inlet temperature T1 is rising is set to be 1°C higher than the boundary temperature when the inlet temperature T1 is falling. Note that this is not limited to 1°C, and may be a fixed value other than 1°C that allows normal operation. Furthermore, instead of a fixed value, it may be a variable value that changes depending on the external environment, etc.

[0080] For example, when the inlet temperature T1 is within the range of the opening reduction region A, the boundary temperature to the opening reduction region B is T I1 The boundary line when the opening decreases from the decreasing region B to the stable region is T I2 On the other hand, when the inlet temperature T1 is in the range of the stable region, the boundary temperature to the opening reduction region B is T I2 +1, and the boundary temperature from the opening reduction region B to the opening reduction region A is T I1 +1.

[0081] (Target outlet temperature table) Fig. 8 is a diagram showing a target outlet temperature table. As shown in Fig. 8, in this embodiment, the target outlet temperature table is divided into five zones, in descending order of temperature, namely, opening degree decreasing zone C, opening degree decreasing zone D, stable zone, opening degree increasing zone D, and opening degree increasing zone C.

[0082] The opening degree increasing region C and the opening degree increasing region D are regions in which the opening degree of the expansion valve 14 is increased, and the opening degree decreasing region C and the opening degree decreasing region D are regions in which the opening degree of the expansion valve 14 is decreased. Here, when the opening degree of the expansion valve 14 in the stable region is used as a reference, the degree of increase in the opening degree is opening degree increasing region C > opening degree increasing region D, and the degree of decrease in the opening degree is opening degree decreasing region C > opening degree decreasing region D.

[0083] By setting the regions in this manner, even if the heating temperature T3 is in a temperature range higher than the stable region, such as the opening decrease region C and the opening decrease region D, the opening of the expansion valve 14 can be reduced to lower the heating temperature T3 to the stable region, and the area of ​​the evaporation region can be controlled to be within a predetermined range. Furthermore, by passing the dehumidified air through the superheat region, it can be warmed and discharged into the room at a temperature close to room temperature. Furthermore, even if the heating temperature T3 is in a temperature range lower than the stable region, such as the opening increase region C and the opening increase region D, the opening of the expansion valve 14 can be increased to raise the heating temperature T3 to the stable region, and a decrease in dehumidification performance due to a wider area of ​​the superheat region can be suppressed.

[0084] Therefore, based on the heating temperature T3, if the evaporation area is narrower than the expected area, the opening of the expansion valve 14 is increased, and if the evaporation area is wider than the expected area, the opening of the expansion valve 14 is decreased, thereby controlling the evaporation area to maintain it within the expected area.

[0085] These regions are T O1 , T O2 , T O3 , T O4 , T O1 +1, T O2 +1, T O3 +1, T O4 It is divided into eight temperatures, T O1 , T O2 , T O1 +1, T O2 +1 indicates the upper limit temperature that is the criterion for determining whether to reduce the opening of the expansion valve 14 in the control process for the dehumidification operation. O3 , T O4 , T O3+1, T O4 +1 indicates the lower limit temperature that is the criterion for determining whether to increase the opening of the expansion valve 14 in the control process for the dehumidifying operation.

[0086] Furthermore, to explain the eight temperatures from another angle, T O1 , T O2 , T O3 , T O4 indicates the boundary temperature when the heating temperature T3 decreases, and T O1 +1, T O2 +1, T O3 +1, T O4 +1 indicates the boundary temperature when the heating temperature T3 is rising. The boundary temperature when the heating temperature T3 is rising is set to be 1°C higher than the boundary temperature when the heating temperature T3 is falling. Note that it is not limited to 1°C, and may be a fixed value other than 1°C that allows normal operation. Furthermore, instead of a fixed value, it may be a variable value that changes depending on the external environment, etc.

[0087] For example, when the heating temperature T3 is within the range of the opening reduction region C, the boundary temperature to the opening reduction region D is T O1 The boundary temperature when the opening decreases from the decreasing region D to the stable region is T O2 On the other hand, when the heating temperature T3 is within the stable region, the boundary temperature to the opening reduction region D is T O2 +1, and the boundary temperature from the opening reduction region D to the opening reduction region C is T O1 +1.

[0088] Incidentally, with regard to the target inlet temperature table and the target outlet temperature table, it is possible that different control commands will be issued on the inlet and outlet sides. For this reason, the air conditioner 1 sets the following priority order: inlet side "decrease expansion valve opening" > outlet side "decrease expansion valve opening" > inlet side "increase expansion valve opening" > outlet side "increase expansion valve opening."

[0089] (Hunting determination process) In order to prevent hunting, the air conditioner 1 performs control to determine hunting based on the outlet temperature T2. Specifically, the number of times the outlet temperature T2 transitions from a state higher than a first temperature (a temperature equal to or lower than the dew point temperature, for example, "inlet temperature -5°C") to a state equal to or lower than the first temperature is counted, and control is performed to temporarily suspend the dehumidification operation based on the number of times.

[0090] Fig. 9 is a flowchart showing the hunting determination process. As shown in Fig. 9, when the dehumidifying operation starts, the control means 100 determines whether or not the outlet temperature T2 is higher than the first temperature (step S301).

[0091] Here, the first temperature is set to a value correlated with the upper limit temperature of the heating temperature T3 in step S103 of Fig. 5. Therefore, when the outlet temperature T2 becomes equal to or lower than the first temperature, the heating temperature T3 becomes higher than the upper limit temperature, so the control means 100 reduces the opening of the expansion valve 14 and the outlet temperature T2 rises. In this embodiment, by setting the first temperature to a value equal to or lower than the dew point temperature, for example, the inlet temperature of -5°C, it is possible to perform stable dehumidification operation without excessively detecting hunting.

[0092] If the outlet temperature T2 is not higher than the first temperature ("No" in step S301), the outlet temperature T2 continues to be compared with the first temperature. On the other hand, if the outlet temperature T2 is higher than the first temperature ("Yes" in step S301), it is determined whether the outlet temperature T2 is equal to or lower than the first temperature (step S302). If the outlet temperature T2 is not equal to or less than the first temperature ("No" in step S302), the comparison is continued until the outlet temperature T2 becomes equal to or less than the first temperature. On the other hand, if the outlet temperature T2 is equal to or less than the first temperature ("Yes" in step S302), it is determined whether the counted number is 0 (step S303).

[0093] If the counted number is 0 ("No" in step S303), the count is incremented by one (step S306).

[0094] After the count is incremented, measurement of the first time period begins (step S307).

[0095] Next, it is determined whether the counted number of times has reached a predetermined number of times (for example, three times) (step S308).

[0096] Next, if the counted number has not reached the predetermined number ("No" in step S308), the counted number remains stored, and it is determined whether the outlet temperature T2 is higher than the first temperature (step S301).

[0097] Returning to step S303, if the counted number is not 0 ("Yes" in step S303), it is determined whether the time since the measurement started in step S307 has passed the first time period (for example, 10 minutes) (step S304).

[0098] If the first time period has not elapsed ("No" in step S304), the count is incremented by one (step S306). On the other hand, if the first time period has elapsed ("Yes" in step S304), the counted number is reset (step S305), and the count is incremented by one (step S306). In this way, if the first time period has elapsed after the count has been incremented by one and before the count is incremented again, the number of counts is reset, thereby enabling hunting to be accurately determined.

[0099] Returning to step S308, if the counted number reaches a predetermined number (for example, 3 times) ("Yes" in step S308), it is determined that hunting has occurred, and the control means 100 temporarily suspends the dehumidification operation described below (step S309).

[0100] Next, it is determined whether a dehumidification operation stop signal has been received by a user operation or the like (step S310), and if it has been received ("Yes" in step S310), the hunting determination process ends. On the other hand, if it has not been received ("No" in step S310), it is determined again whether the outlet temperature T2 is higher than the first temperature (step S301).

[0101] FIG. 10 is a diagram showing the relationship between the outlet temperature and elapsed time during dehumidification operation. In the example shown in FIG. 10, when the outlet temperature T2 falls below the first temperature after the dehumidification operation is started, the count is incremented by one (count 1). Next, when the outlet temperature T2 falls below the first temperature again after 8 minutes, which is less than the first time, have elapsed, the count is incremented by another one (count 2). Next, when the outlet temperature T2 falls below the first temperature again after 11 minutes, which is equal to or greater than the first time, have elapsed, the count is reset and then incremented by one (count 1). Next, when the outlet temperature T2 falls below the first temperature again after 8 minutes, which is less than the first time, have elapsed, the count is incremented by one more (count 2). Next, when the outlet temperature T2 falls below the first temperature again after 9 minutes, which is less than the first time, have elapsed, the count is incremented by one more (count 3). When the number of counts thus counted reaches a predetermined number (3), the control means 100 determines that hunting has occurred.

[0102] In the above control, the number of times the temperature has transitioned to a state equal to or lower than the first temperature is counted, and the dehumidifying operation is temporarily stopped based on the number of times. However, the number of times the temperature has transitioned from a state higher than the first temperature to a state equal to or lower than the first temperature and then again to a state higher than the first temperature may be counted, and the dehumidifying operation may be temporarily stopped based on the number of times. Next, the hunting determination process in this case will be described.

[0103] Fig. 11 is a flowchart showing the hunting determination process. In the hunting determination process shown in Fig. 11, similarly to the hunting determination process shown in Fig. 9, when the dehumidifying operation starts, the control means 100 determines whether the outlet temperature T2 is higher than the first temperature (step S301).

[0104] If the outlet temperature T2 is not higher than the first temperature ("No" in step S301), the outlet temperature T2 continues to be compared with the first temperature. On the other hand, if the outlet temperature T2 is higher than the first temperature ("Yes" in step S301), it is determined whether the outlet temperature T2 is equal to or lower than the first temperature (step S302).

[0105] If the outlet temperature T2 is not equal to or less than the first temperature ("No" in step S302), the comparison is continued until the outlet temperature T2 becomes equal to or less than the first temperature. On the other hand, if the outlet temperature T2 is equal to or less than the first temperature ("Yes" in step S302), it is again determined whether the outlet temperature T2 is higher than the first temperature (step S501).

[0106] If the outlet temperature T2 is not higher than the first temperature ("No" in step S501), the outlet temperature T2 continues to be compared with the first temperature. On the other hand, if the outlet temperature T2 is higher than the first temperature ("Yes" in step S501), it is determined whether the counted number is not 0 (step S303). Thereafter, steps S303 to S310 are the same as the hunting determination process shown in FIG. 9.

[0107] As described above, the control for determining hunting during dehumidification operation in which part of the indoor heat exchanger 21 is used as the evaporation region has been described, but the conditions are not limited to those described above. For example, in this embodiment, the predetermined number of times for determining hunting is set to three times, and the first time period is set to 10 minutes, but the present invention is not limited to these values, and any combination of the number of times and time period may be used as long as hunting can be correctly determined.

[0108] In addition, in this embodiment, the first temperature is set to a value equal to or lower than the dew point temperature, but it may be set to a value equal to or higher than the dew point temperature. If the first temperature is set to a value equal to or higher than the dew point temperature, the count advances when the outlet temperature T2 becomes equal to or lower than the dew point temperature, and hunting is determined to have occurred, so no dehumidifying effect is achieved in the overheated region. Therefore, the dehumidified air can be efficiently heated in the overheated region.

[0109] In addition, in this embodiment, the timing for resetting the count (steps S304 and S305) is set to after the outlet temperature T2 becomes equal to or lower than the first temperature (step S302), but this is not limited to this. For example, it may be determined whether or not the first time has elapsed before the outlet temperature T2 becomes equal to or lower than the first temperature (step S302), and the count may be reset if the first time has elapsed.

[0110] Furthermore, in this embodiment, the first temperature is compared with the outlet temperature T2 in step S301, but instead of the first temperature, the outlet temperature T2 may be compared with a fourth temperature that is higher than the first temperature. This prevents the outlet temperature T2 from fluctuating around the first temperature and being judged to be hunting when the control of the dehumidification operation is unstable.

[0111] Below, we will explain the details of the control that counts the number of times the outlet temperature T2 transitions from a state higher than the first temperature to a state below the first temperature, or the number of times the outlet temperature T2 transitions from a state higher than the first temperature to a state below the first temperature and then again to a state higher than the first temperature, and temporarily suspends the dehumidification operation based on this number of times.

[0112] (Dehumidification operation temporary stop processing) Fig. 12 is a flowchart showing the process of temporarily suspending the dehumidifying operation. As shown in Fig. 12, when the control means 100 determines that hunting has occurred, it stops the dehumidifying operation to return to normal operation (step S401).

[0113] Next, the control means 100 determines whether the stop time has passed the second time (step S402), and if not ("No" in step S402), continues to stop the dehumidification operation until the second time has passed.

[0114] On the other hand, if the stop time has passed the second time period ("Yes" in step S402), the control means 100 restarts the dehumidifying operation (step S401) and ends the temporary suspension of the dehumidifying operation. [Industrial Applicability]

[0115] An air conditioner and a method for controlling an air conditioner according to one aspect of the present disclosure can be widely applied to various air conditioners, including air conditioners used in ordinary homes. [Explanation of symbols]

[0116] 1. Air conditioner 11 Compressor 13 Outdoor heat exchanger 14 Expansion valve 21 Indoor heat exchanger 26 Temperature detection means (outlet temperature detection means) 100 Control means

Claims

1. a refrigerant circuit configured by connecting a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger; a temperature detection means for detecting the temperature of the indoor heat exchanger; a control means for controlling the refrigerant circuit, The control means counts the number of times that the temperature detected by the temperature detection means transitions from a state higher than a first temperature to a state lower than the first temperature during dehumidification operation, or the number of times that the temperature transitions from a state higher than the first temperature to a state lower than the first temperature and then transitions again to a state higher than the first temperature, and temporarily suspends the dehumidification operation based on the number of times.

2. 2. The air conditioner according to claim 1, wherein the control means temporarily suspends the dehumidifying operation when the number of times reaches a predetermined number.

3. 3. The air conditioner according to claim 1, wherein the control means controls a part of the indoor heat exchanger to be an evaporation zone and another part to be a superheat zone during the dehumidifying operation.

4. The air conditioner according to claim 3, characterized in that, during the dehumidifying operation, the control means increases the opening degree of the expansion valve when the evaporation area is narrower than the planned area, and decreases the opening degree of the expansion valve when the evaporation area is wider than the planned area.

5. The air conditioner according to claim 3 or 4, characterized in that, during the dehumidification operation, the control means increases the opening degree of the expansion valve when the temperature of the evaporation zone is equal to or lower than a second temperature, and decreases the opening degree of the expansion valve when the temperature of the evaporation zone is equal to or higher than a third temperature higher than the second temperature.

6. 5. The air conditioner according to claim 4, wherein the temperature detecting means is disposed near an outlet of the predetermined area.

7. 7. The air conditioner according to claim 1, wherein the first temperature is set to a dew point temperature or lower.

8. An air conditioner as described in any one of claims 1 to 7, characterized in that the control means resets the counted number of times if a first time has elapsed between the time the count is incremented and the time the count is incremented again.

9. 9. The air conditioner according to claim 1, wherein the control means continues the temporary suspension for a second period of time.

10. a refrigerant circuit configured by connecting a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger; a temperature detection means for detecting the temperature of the indoor heat exchanger; A control method for an air conditioner comprising: a control means for controlling the refrigerant circuit, The control means counts the number of times that the temperature detected by the temperature detection means during dehumidification operation transitions from a state higher than a first temperature to a state lower than the first temperature, or the number of times that the temperature transitions from a state higher than the first temperature to a state lower than the first temperature and then transitions again to a state higher than the first temperature, and temporarily suspends the dehumidification operation based on the number of times.

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