Air-conditioning system and control method

Abstract

This air-conditioning system comprises: an operation unit that receives an operation for setting one common set temperature in a cooling operation and a heating operation; a temperature sensor that detects the temperature in the air-conditioning system; and a control unit that controls switching between the cooling operation and the heating operation on the basis of a change in the temperature difference between the set temperature set by the operation unit and the detected temperature detected by the temperature sensor. The control unit switches from the cooling operation to the heating operation assuming, as a first condition, that the detected temperature after a change in temperature when the temperature difference changes in the cooling operation is lower than the set temperature by a predetermined threshold value or more, and switches from the heating operation to the cooling operation assuming, as a second condition, that the detected temperature after a change in temperature when the temperature difference changes in the heating operation is higher than the set temperature by a predetermined threshold value or more. The control unit continues the cooling operation in a case where the first condition is not satisfied in the cooling operation, and continues the heating operation in a case where the second condition is not satisfied in the heating operation.

Description

Air conditioning system and control method

[0001] The present disclosure relates to an air conditioning system and a control method.

[0002] BACKGROUND ART Conventionally, an air conditioning system has been disclosed in which, as one of the functions of a thermostat, target temperatures for cooling and heating are set, and the system operates while automatically switching between cooling and heating (for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2003-114043

[0004] As described above, when automatically switching between operating states using a set temperature as a target value, if a single set temperature can be used as the target value for cooling and heating, the user can set an optimal temperature that they find comfortable regardless of whether they are using cooling or heating. However, if switching between cooling and heating operations is performed using a single set temperature as the target value, there is a concern that the operation state may become unstable due to frequent switching between cooling and heating operations near the set temperature.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and one of its objectives is to provide an air conditioning system and a control method that prevent the operating state from becoming unstable when switching between cooling operation and heating operation using a single set temperature as a target value.

[0006] The air conditioning system according to the present disclosure includes an outdoor unit having a compressor, an outdoor unit heat exchanger, and an outdoor unit fan, an indoor unit having an indoor unit heat exchanger and an indoor unit fan, and refrigerant piping connecting the outdoor unit and the indoor unit, and performs at least a cooling operation or a heating operation, and includes an operation unit that accepts an operation to set a single set temperature common to the cooling operation and the heating operation, a temperature sensor that detects a temperature within the air conditioning system, and a temperature sensor that switches between the cooling operation and the heating operation based on a change in the temperature difference between the set temperature set by the operation unit and the detected temperature detected by the temperature sensor. and a control unit that controls the cooling operation, wherein the control unit switches from the cooling operation to the heating operation on the condition that a first condition is met that the detected temperature after a change when the temperature difference changes during the cooling operation is lower than the set temperature by a predetermined threshold or more, and switches from the heating operation to the cooling operation on the condition that a second condition is met that the detected temperature after a change when the temperature difference changes during the heating operation is higher than the set temperature by a predetermined threshold or more, and continues the cooling operation if the first condition is not met during the cooling operation, and continues the heating operation if the second condition is not met during the heating operation.

[0007] Further, a control method for an air conditioning system according to the present disclosure is a control method for an air conditioning system that includes an outdoor unit having a compressor, an outdoor unit heat exchanger, and an outdoor unit fan, an indoor unit having an indoor unit heat exchanger and an indoor unit fan, and refrigerant piping connecting the outdoor unit and the indoor unit, and that performs at least a cooling operation or a heating operation, the control method including the steps of: an operation unit accepting an operation to set one set temperature common to the cooling operation and the heating operation; a temperature sensor detecting a temperature within the air conditioning system; and a control unit switching between the cooling operation and the heating operation based on a change in the temperature difference between the set temperature set by the operation unit and the detected temperature detected by the temperature sensor. and controlling the switching between the cooling operation and the heating operation, wherein when the control unit controls the switching between the cooling operation and the heating operation, the control unit switches from the cooling operation to the heating operation on the first condition that the detected temperature after a change when the temperature difference changes in the cooling operation is lower than the set temperature by a predetermined threshold or more, and switches from the heating operation to the cooling operation on the second condition that the detected temperature after a change when the temperature difference changes in the heating operation is higher than the set temperature by a predetermined threshold or more, and continues the cooling operation if the first condition is not satisfied in the cooling operation, and continues the heating operation if the second condition is not satisfied in the heating operation.

[0008] According to the present disclosure, it is possible to prevent the operating state from becoming unstable when switching between cooling operation and heating operation using one set temperature as a target value.

[0009] A block diagram showing a schematic configuration example of an air conditioning system according to a first embodiment. A block diagram showing a schematic configuration example of a refrigerant circuit according to the first embodiment. A diagram showing an example of operation switching control according to the first embodiment. A flowchart showing an example of operation switching control processing according to the first embodiment. A diagram showing an example of operation switching control according to a second embodiment. A diagram showing a detailed example of switching control between cooling operation and dehumidification operation according to the second embodiment. A flowchart showing an example of operation switching control processing according to the second embodiment.

[0010] Hereinafter, embodiments will be described with reference to the drawings. First Embodiment First, the first embodiment will be described. [Configuration of Air Conditioning System] FIG. 1 is a block diagram showing a schematic configuration example of an air conditioning system according to this embodiment. The illustrated air conditioning system 1 has a system configuration assumed for a detached house. Note that, although an example of an air conditioning system 1 assumed for a detached house is shown here, the same applies to condominiums, offices, buildings, etc.

[0011] The air conditioning system 1 is configured as a refrigerant circuit including one outdoor unit 10 (outdoor unit) installed outdoors, one indoor unit 20 (indoor unit) installed indoors, and refrigerant piping 5 connecting the outdoor unit 10 and the indoor unit 20.

[0012] 2 is a block diagram showing a schematic configuration example of a refrigerant circuit in the air conditioning system according to this embodiment. The outdoor unit 10 and the indoor unit 20 are connected by refrigerant piping 5 (5a, 5b). The outdoor unit 10 includes a compressor 13, an outdoor heat exchanger 14, a four-way valve 15, an expansion valve 16, and an outdoor fan 17. The indoor unit 20 includes an indoor heat exchanger 25 and an indoor fan 27.

[0013] The four-way valve 15 provided in the outdoor unit 10 is switched to change the direction of refrigerant circulation, thereby switching between heating operation and cooling operation.

[0014] In heating operation, the gaseous refrigerant compressed by the compressor 13 flows through the four-way valve 15 and the refrigerant pipe 5a to the indoor unit heat exchanger 25. The refrigerant in the indoor unit heat exchanger 25 exchanges heat with the surrounding air to warm it. The refrigerant that has become liquid through the heat exchange passes through the refrigerant pipe 5b and the expansion valve 16 and flows into the outdoor unit heat exchanger 14. The refrigerant in the outdoor unit heat exchanger 14 exchanges heat with the surrounding air. The refrigerant that has become gaseous through the heat exchange passes through the four-way valve 15 and returns to the compressor 13.

[0015] During cooling operation, the gaseous refrigerant compressed by the compressor 13 flows through the four-way valve 15 into the outdoor heat exchanger 14. The refrigerant in the outdoor heat exchanger 14 exchanges heat with the surrounding air. The refrigerant that has become liquid through heat exchange passes through the expansion valve 16 and refrigerant pipe 5b, and flows into the indoor heat exchanger 25. The refrigerant in the indoor heat exchanger 25 exchanges heat with the surrounding air, cooling it. The refrigerant that has become gaseous through heat exchange returns to the compressor 13 through the four-way valve 15 via the refrigerant pipe 5a.

[0016] Returning to Figure 1, each room is provided with an intake port 3 for drawing in air from the room and an outlet port 4 for blowing out air blown out from the indoor unit 20 into the room. The air drawn in through the intake port 3 provided in each room is taken into the indoor unit 20 via an intake-side duct 6. The air blown out from the indoor unit 20 is released from the outlet port 4 provided in each room via an outlet-side duct 7.

[0017] Also provided within the air conditioning system 1 are a temperature sensor 8 that detects temperature and a humidity sensor 9 that detects humidity. For example, the temperature sensor 8 is provided near where the intake duct 6 in the indoor unit 20 is connected so as to detect the temperature of the air drawn in through the intake port 3 (intake temperature). Similarly, the humidity sensor 9 is provided near where the intake duct 6 in the indoor unit 20 is connected so as to detect the humidity of the air drawn in through the intake port 3 (intake humidity). The temperature (intake temperature) and humidity (intake humidity) of the air drawn in through the intake port 3 correspond to the temperature and humidity of the air in the room.

[0018] The air conditioning system 1 also includes an operation unit 30 and a control unit 40. The operation unit 30 accepts user operations for the air conditioning system 1. For example, the operation unit 30 accepts operations to set the set temperatures (target values) for at least cooling operation and heating operation. The set temperatures for cooling operation and heating operation are set as a single common set temperature. By operating the operation unit 30, the user can set the optimal set temperature that the user considers comfortable, regardless of whether the operation is cooling or heating.

[0019] The operation unit 30 is communicatively connected to the outdoor unit 10 and the indoor unit 20, and transmits control signals to the outdoor unit 10 and the indoor unit 20 to control the air conditioning system 1 based on user operations.

[0020] The control unit 40 controls the operation of the air conditioning system 1. The control unit 40 may be provided in the outdoor unit 10 or in the indoor unit 20. The control unit 40 may also be configured so that the control unit provided in the outdoor unit 10 and the control unit provided in the indoor unit 20 cooperate to perform control.

[0021] The control unit 40 acquires the set temperature set by the operation unit 30 from the operation unit 30. The control unit 40 also acquires the detected temperature detected by the temperature sensor 8 from the temperature sensor 8. The control unit 40 then performs operation switching control to control switching between the cooling operation and the heating operation based on the temperature difference between the set temperature set by the operation unit 30 and the detected temperature detected by the temperature sensor 8. For example, the control unit 40 controls switching between the cooling operation and the heating operation based on a change in the temperature difference between the set temperature set by the operation unit 30 and the detected temperature detected by the temperature sensor 8.

[0022] [Example of Operation Switching Control] Fig. 3 is a diagram showing an example of operation switching control in the air conditioning system according to this embodiment. In this diagram, the vertical axis represents the temperature difference (ΔT) between the set temperature and the detected temperature (intake temperature). Here, the "set temperature - detected temperature" will be described as the temperature difference (ΔT). Also, in this diagram, cooling (weak), cooling (medium), and cooling (strong) are distinguished by differences in cooling capacity during cooling operation, with cooling capacity increasing in the order of cooling (weak), cooling (medium), and cooling (strong). Similarly, heating (weak), heating (medium), and heating (strong) are distinguished by differences in heating capacity during heating operation, with heating capacity increasing in the order of heating (weak), heating (medium), and heating (strong).

[0023] For example, when the temperature difference (ΔT) changes from -5°C (i.e., the detected temperature is 5°C higher than the set temperature) and the cooling operation is in progress at high cooling, to -4°C, the control unit 40 reduces the cooling capacity and changes to cooling operation at medium cooling.

[0024] Furthermore, when the detected temperature drops due to the temperature difference (ΔT) of -4°C and the cooling operation is performed at medium cooling, if the temperature difference (ΔT) changes from -4°C to -3°C, the control unit 40 further reduces the cooling capacity and changes to cooling operation at low cooling.

[0025] Furthermore, the control unit 40 continues the cooling operation at cooling (weak) even when the detected temperature gradually decreases by performing cooling operation at cooling (weak) when the temperature difference (ΔT) is -3°C, and the temperature difference (ΔT) changes sequentially from -3°C to -2°C, -1°C, 0°C, 1°C, and 2°C. Then, the control unit 40 switches to heating operation at heating (weak) when the temperature difference (ΔT) becomes 3°C (i.e., the detected temperature is 3°C lower than the set temperature).

[0026] That is, the control unit 40 switches from cooling operation to heating operation on the condition (cooling-to-heating switching condition: first condition) that the detected temperature after the change in temperature difference (ΔT) during cooling operation is lower than the set temperature by a predetermined threshold value or more (here, lower by 3°C or more). If the above-mentioned cooling-to-heating switching condition (first condition) during cooling operation is not satisfied, the control unit 40 continues the cooling operation without switching from cooling operation to heating operation.

[0027] In addition, when the temperature difference (ΔT) changes from a state in which heating / cooling (high) heating operation is being performed when the temperature difference (ΔT) is 5°C (i.e., a state in which the detected temperature is 5°C lower than the set temperature) to a state in which the temperature difference (ΔT) changes to 4°C, the control unit 40 reduces the heating capacity and changes to heating (medium) heating operation.

[0028] Furthermore, when the detected temperature rises due to the temperature difference (ΔT) of 4°C and the heating operation is performed at medium heating, if the temperature difference (ΔT) changes from 4°C to 3°C, the control unit 40 further reduces the heating capacity and changes to heating operation at low heating.

[0029] Furthermore, the control unit 40 continues the heating operation at low heating mode when the temperature difference (ΔT) is 3° C., causing the detected temperature to gradually increase, even when the temperature difference (ΔT) changes sequentially from 3° C. to 2° C., 1° C., 0° C., −1° C., and −2° C. Then, the control unit 40 switches to the cooling operation at low cooling mode when the temperature difference (ΔT) becomes −3° C. (i.e., the detected temperature is 3° C. higher than the set temperature).

[0030] That is, the control unit 40 switches from heating operation to cooling operation on the condition (condition for switching from heating to cooling: second condition) that the detected temperature after the change in temperature difference (ΔT) during heating operation is higher than the set temperature by a predetermined threshold or more (here, higher by 3°C or more). If the condition for switching from heating to cooling (second condition) during heating operation is not satisfied, the control unit 40 continues the heating operation without switching from heating operation to cooling operation.

[0031] In this way, the control unit 40 sets a difference (differential) between the temperature difference (ΔT) at which the cooling operation is switched to the heating operation and the temperature difference (ΔT) at which the heating operation is switched to the cooling operation, thereby preventing the air conditioning system 1 from frequently switching between the cooling operation and the heating operation.

[0032] Note that the temperature difference (ΔT) and the switching control between the cooling operation and the heating operation shown in Figure 3 are merely examples and are not limited to these. For example, the temperature difference (ΔT) conditions that are the conditions for switching from cooling to heating and from heating to cooling can be set arbitrarily. In addition, the temperature difference (ΔT) conditions that change the cooling capacity in the cooling operation and the temperature difference (ΔT) conditions that change the heating capacity in the heating operation can also be set arbitrarily.

[0033] [Operation of Operation Switching Control Process] Next, with reference to Fig. 4, an operation of the operation switching control process in which the control unit 40 controls switching between the cooling operation and the heating operation based on the temperature difference (ΔT) between the set temperature and the detected temperature (suction temperature) in the air conditioning system 1 will be described. Fig. 4 is a flowchart showing an example of the operation switching control process according to this embodiment.

[0034] (Step S101) The control unit 40 acquires the set temperature set by the operation unit 30 from the operation unit 30. The control unit 40 also acquires the detected temperature detected by the temperature sensor 8 from the temperature sensor 8. The control unit 40 then acquires the temperature difference (ΔT) between the set temperature set by the operation unit 30 and the detected temperature detected by the temperature sensor 8. Then, the process proceeds to step S103.

[0035] (Step S103) The control unit 40 determines whether the temperature difference (ΔT) has not changed. If the control unit 40 determines that the temperature difference (ΔT) has not changed (YES), the process proceeds to step S107. On the other hand, if the control unit 40 determines that the temperature difference (ΔT) has changed (NO), the process proceeds to step S113.

[0036] (Step S107) The control unit 40 continues the current operating state. For example, if the current operating state is cooling (weak), the control unit 40 continues the cooling operation with cooling (weak). If the current operating state is cooling (medium), the control unit 40 continues the cooling operation with cooling (medium). If the current operating state is cooling (strong), the control unit 40 continues the cooling operation with cooling (strong). Furthermore, if the current operating state is heating (weak), the control unit 40 continues the heating operation with heating (weak). If the current operating state is heating (medium), the control unit 40 continues the heating operation with heating (medium). If the current operating state is heating (strong), the control unit 40 continues the heating operation with heating (strong). Then, the process returns to step S101.

[0037] (Step S113) The control unit 40 determines whether the change in temperature difference (ΔT) has satisfied the cooling / heating switching condition described with reference to Fig. 3. If the control unit 40 determines that the cooling / heating switching condition has been satisfied (YES), the process proceeds to step S115. On the other hand, if the control unit 40 determines that the cooling / heating switching condition has not been satisfied (NO), the process proceeds to step S121.

[0038] (Step S115) The control unit 40 determines whether the condition satisfied in step S113 is the condition for switching from heating to cooling (second condition). If the control unit 40 determines that the condition for switching from heating to cooling (second condition) is satisfied (YES), the control unit 40 proceeds to step S117. On the other hand, if the control unit 40 determines that the condition for switching from cooling to heating (first condition) is satisfied (NO), the control unit 40 proceeds to step S191.

[0039] (Step S117) The control unit 40 switches from the heating operation to the cooling operation. For example, the control unit 40 switches from the heating operation (low) to the cooling operation (low) (see FIG. 3). Then, the process returns to step S101.

[0040] (Step S119) The control unit 40 switches from the cooling operation to the heating operation. For example, the control unit 40 switches from the cooling operation with cooling (weak) to the heating operation with heating (weak) (see FIG. 3). Then, the process returns to step S101.

[0041] (Step S121) The control unit 40 determines whether a condition for changing the output power in cooling or heating operation is satisfied due to a change in the temperature difference (ΔT). The output change refers to a change in the cooling capacity, such as cooling (low), cooling (medium), or cooling (high), in cooling operation, or a change in the heating capacity, such as heating (low), heating (medium), or heating (high), in heating operation, as described with reference to FIG. 3 . If the control unit 40 determines that the condition for changing the output power is satisfied due to a change in the temperature difference (ΔT) (YES), the control unit 40 proceeds to step S123. On the other hand, if the control unit 40 determines that the condition for changing the output power is not satisfied even if the temperature difference (ΔT) has changed (NO), the control unit 40 continues the current operating state (step S107). Then, the control unit 40 returns to step S101.

[0042] (Step S123) The control unit 40 changes the output in response to a change in the temperature difference (ΔT). For example, when the control unit 40 is performing cooling operation, the control unit 40 changes the output to one of cooling (weak), cooling (medium), and cooling (strong) in response to a change in the temperature difference (ΔT). When the control unit 40 is performing heating operation, the control unit 40 changes the output to one of heating (weak), heating (medium), and heating (strong) in response to a change in the temperature difference (ΔT). Then, the process returns to step S101.

[0043] As described above, the air conditioning system 1 according to this embodiment includes an outdoor unit 10 (an example of an outdoor unit) including a compressor 13, an outdoor heat exchanger 14, and an outdoor fan 17; an indoor unit 20 (an example of an indoor unit) including an indoor heat exchanger 25 and an indoor fan 27; and refrigerant piping 5 connecting the outdoor unit 10 and the indoor fan 27. The air conditioning system 1 also includes a temperature sensor 8 that detects a temperature within the air conditioning system 1, an operation unit 30, and a control unit 40. The operation unit 30 accepts an operation to set a single set temperature common to both the cooling and heating operations. The control unit 40 controls switching between the cooling and heating operations based on changes in the temperature difference (ΔT) between the set temperature set by the operation unit 30 and the detected temperature detected by the temperature sensor 8.

[0044] For example, the control unit 40 switches from cooling operation to heating operation using a condition (first condition) for switching from cooling to heating that the detected temperature after a change in the temperature difference (ΔT) during cooling operation is lower than the set temperature by a predetermined threshold or more. On the other hand, if the condition (first condition) for switching from cooling to heating during cooling operation is not met, the control unit 40 continues the cooling operation. Furthermore, the control unit 40 switches from heating operation to cooling operation using a condition (second condition) for switching from heating to cooling that the detected temperature after a change in the temperature difference (ΔT) during heating operation is higher than the set temperature by a predetermined threshold or more. On the other hand, if the condition (second condition) for switching from heating to cooling during heating operation is not met, the control unit 40 continues the heating operation.

[0045] As a result, when the air conditioning system 1 automatically switches between cooling operation and heating operation in response to changes in the temperature difference (ΔT) between the set temperature and the detected temperature (actual temperature), by providing a difference (differential) between the temperature difference (ΔT) at which the air conditioning system 1 switches from cooling operation to heating operation and the temperature difference (ΔT) at which the air conditioning system 1 switches from heating operation to cooling operation, frequent switching between cooling operation and heating operation can be suppressed. Thus, the air conditioning system 1 can suppress unstable operating conditions when switching between cooling operation and heating operation using one set temperature as a target value.

[0046] For example, the temperature sensor 8 is provided in the indoor unit 20. This allows the air conditioning system 1 to detect the actual temperature of the air in the room and appropriately switch between cooling operation and heating operation.

[0047] For example, as shown in Figure 1, by installing a temperature sensor 8 near where the intake duct 6 of the indoor unit 20 is connected, it is possible to detect and control the temperature of the room air sucked in through the intake port 3 (intake temperature), thereby appropriately bringing the room temperature close to the set temperature and increasing comfort.

[0048] Furthermore, since the air conditioning system 1 according to this embodiment is a whole-building air conditioning system in which the intakes 3 and exhausts 4 of multiple rooms are connected to the indoor unit 20 by ducts, the temperature of all rooms can be brought closer to the set temperature by controlling the switching between cooling and heating operation as described above, thereby increasing comfort.

[0049] Furthermore, in this embodiment, the air conditioning system 1 includes an outdoor unit 10 (an example of an outdoor unit) having a compressor 13, an outdoor unit heat exchanger 14, and an outdoor unit fan 17, an indoor unit 20 (an example of an indoor unit) having an indoor unit heat exchanger 25 and an indoor unit fan 27, and refrigerant piping 5 connecting the outdoor unit 10 and the indoor unit fan 27, and performs at least cooling operation or heating operation. The control method for this air conditioning system 1 includes the steps of: an operation unit 30 accepting an operation to set a single set temperature common to cooling operation and heating operation; a temperature sensor 8 detecting a temperature within the air conditioning system 1; and a control unit 40 controlling switching between cooling operation and heating operation based on a change in the temperature difference (ΔT) between the set temperature set by the operation unit 30 and the detected temperature detected by the temperature sensor 8.

[0050] Furthermore, when the control unit 40 controls the switching between cooling operation and heating operation, it switches from cooling operation to heating operation using the condition (first condition) for switching from cooling to heating that the detected temperature after the change when the temperature difference (ΔT) changes during cooling operation is lower than the set temperature by a predetermined threshold or more, and it switches from heating operation to cooling operation using the condition (second condition) for switching from heating to cooling that the detected temperature after the change when the temperature difference (ΔT) changes during heating operation is higher than the set temperature by a predetermined threshold or more, and continues cooling operation if the condition (first condition) for switching from cooling to heating during cooling operation is not met, and continues heating operation if the condition (second condition) for switching from heating to cooling during heating operation is not met.

[0051] As a result, the control method in air conditioning system 1, when automatically switching between cooling operation and heating operation in response to changes in the temperature difference (ΔT) between the set temperature and the detected temperature (actual temperature), can prevent frequent switching between cooling operation and heating operation by providing a difference (differential) between the temperature difference (ΔT) at which cooling operation switches to heating operation and the temperature difference (ΔT) at which heating operation switches to cooling operation. Thus, the control method in air conditioning system 1 can prevent the operating state from becoming unstable when switching between cooling operation and heating operation using one set temperature as a target value.

[0052] Second Embodiment Next, a second embodiment will be described. In the first embodiment, the operation switching control for controlling switching between the cooling operation and the heating operation has been described. In the present embodiment, the operation switching control for controlling switching to the dehumidifying operation in addition to controlling switching between the cooling operation and the heating operation will be described.

[0053] The air conditioning system 1 performs the same control as in the first embodiment for heating operation. Meanwhile, for cooling operation, the air conditioning system 1 continues cooling operation when the temperature difference (ΔT) is large and cooling capacity is required. However, when the temperature difference (ΔT) subsequently decreases and the system switches to cooling operation (low), it switches to dehumidification operation based on the relationship between the actual humidity and the set humidity at that time. When the actual humidity is high, the air conditioning system 1 controls the dehumidification operation with high dehumidification capacity to adjust the humidity closer to the set humidity. In this case, the air conditioning system 1 variably controls the airflow depending on the indoor unit 20 to maintain a constant evaporation temperature, which makes it easier to reach the target set humidity and maintain comfort. The configuration of the air conditioning system 1 according to this embodiment will be specifically described below.

[0054] The configuration of the air conditioning system 1 according to this embodiment is the same as the configuration shown in Figures 1 and 2, and therefore the description thereof will be omitted as appropriate. Here, the control for switching between the cooling operation and the dehumidifying operation in the operation switching control according to this embodiment, which is different from that in the first embodiment, will be described.

[0055] In this embodiment, the operation unit 30 accepts an operation to set a set humidity (target value) in addition to the set temperatures for cooling operation and heating operation. The user can set an optimum set humidity that is considered comfortable by operating the operation unit 30.

[0056] The control unit 40 acquires the set humidity set by the operation unit 30 from the operation unit 30. The control unit 40 also acquires the detected humidity (suction humidity) detected by the humidity sensor 9 from the humidity sensor 9. The control unit 40 then acquires the humidity difference (relative humidity) between the set humidity set by the operation unit 30 and the detected humidity detected by the humidity sensor 9, and controls switching between the cooling operation and the dehumidifying operation based on the relative humidity and the temperature difference (ΔT).

[0057] Figure 5 is a diagram showing an example of operation switching control in the air conditioning system according to this embodiment. In this figure, the vertical axis represents the temperature difference (ΔT) as in Figure 3, but the horizontal axis also represents relative humidity. Here, the explanation will be given assuming that the relative humidity is "detected humidity - set humidity."

[0058] The conditions for switching from cooling to heating (first condition) and from heating to cooling (second condition) are basically the same as those in the control of the first embodiment shown in Figure 3. However, the control unit 40 switches to dehumidification operation in accordance with the relative humidity when the temperature difference (ΔT) on the cooling operation side is small (here, ΔT is -3°C) and cooling operation is being performed at low cooling mode. Basically, the control unit 40 controls to cooling operation when the relative humidity is 0% or less, i.e., the detected humidity (actual humidity) is lower than the set humidity, and controls to dehumidification operation when the relative humidity is higher than 0%, i.e., the detected humidity (actual humidity) is higher than the set humidity.

[0059] In the illustrated example, the dehumidification operation is also classified into three levels based on the dehumidification capacity: weak, medium, and strong, with the dehumidification capacity increasing in the order of weak, medium, and strong. The control unit 40 controls the dehumidification operation to have a higher dehumidification capacity as the relative humidity increases.

[0060] Here, dehumidification operation is an operation mode in which the rotation speed of the fan (e.g., the indoor unit fan 27) is controlled to be lower during cooling operation. In other words, dehumidification operation in dehumidification (weak) mode corresponds to cooling operation in which the rotation speed of the fan is controlled to be lower than that during cooling operation in dehumidification (weak). Furthermore, since the dehumidifying capacity increases as the rotation speed of the fan is lowered, the rotation speed of the fan decreases in the order of dehumidification (weak), dehumidification (medium), and dehumidification (strong). Note that the method of dehumidification operation is not limited to the above control, and other methods may be used.

[0061] 6 is a diagram showing a detailed example of switching control between the cooling operation and the dehumidifying operation according to this embodiment, which shows a detailed example of switching control between the cooling operation and the dehumidifying operation when the temperature difference (ΔT) is small (here, ΔT is −3° C.) on the cooling operation side shown in FIG.

[0062] When the control unit 40 is performing cooling operation at low cooling mode and the relative humidity rises from minus to 0%, the control unit 40 switches the operation to dehumidification operation at low dehumidification mode. Furthermore, when the control unit 40 is performing dehumidification operation at low dehumidification mode and the relative humidity rises to 10%, the control unit 40 switches the operation to dehumidification operation at medium dehumidification mode and the relative humidity rises to 20%. Furthermore, when the control unit 40 is performing dehumidification operation at medium dehumidification mode and the relative humidity rises to 20%, the control unit 40 switches the operation to dehumidification operation at high dehumidification mode.

[0063] On the other hand, when the dehumidification operation is in the dehumidification (strong) mode, the control unit 40 changes the dehumidification operation to the dehumidification (medium) mode if the relative humidity drops to 10%. Furthermore, when the dehumidification operation is in the dehumidification (medium) mode and the relative humidity drops to 0%, the control unit 40 changes the dehumidification operation to the dehumidification (weak) mode, and continues the dehumidification operation for a while even after the set humidity is reached. Furthermore, when the dehumidification operation is in the dehumidification (weak) mode and the relative humidity drops to -10%, the control unit 40 switches the operation to the cooling (weak) mode.

[0064] In this way, the control unit 40 controls the switching between cooling operation and dehumidification operation based on the relative humidity when the temperature difference (ΔT) is within a predetermined range, and makes the relative humidity conditions when switching from cooling operation to dehumidification operation different from the relative humidity conditions when switching from dehumidification operation to cooling operation.

[0065] That is, the control unit 40 sets a difference (differential) between the relative humidity at which the cooling operation is switched to the dehumidifying operation and the relative humidity at which the dehumidifying operation is switched to the cooling operation, thereby preventing the air conditioning system 1 from frequently switching between the cooling operation and the dehumidifying operation.

[0066] Furthermore, when switching the dehumidification capacity during dehumidification operation, the control unit 40 differentiates the relative humidity conditions for changing from dehumidification (weak) to dehumidification (medium) from the relative humidity conditions for changing from dehumidification (medium) to dehumidification (weak), and also differentiates the relative humidity conditions for changing from dehumidification (medium) to dehumidification (strong) from the relative humidity conditions for changing from dehumidification (strong) to dehumidification (medium).

[0067] In this way, when switching the dehumidification capacity during dehumidification operation, the control unit 40 sets a difference (differential) between the relative humidity at which the dehumidification capacity is changed from weak dehumidification to medium dehumidification to strong dehumidification and the relative humidity at which the dehumidification capacity is changed from strong dehumidification to medium dehumidification to weak dehumidification. This allows the air conditioning system 1 to prevent the dehumidification capacity from being frequently switched during dehumidification operation.

[0068] 5 and 6 are merely examples, and are not intended to be limiting. For example, an example has been shown in which the temperature difference (ΔT) for controlling switching between cooling and dehumidifying operations is -3°C, but the temperature difference (ΔT) is not limited to -3°C and may be -2°C, or may be in the range of -3 to -2°C. Furthermore, the relative humidity conditions for switching between cooling and dehumidifying operations, and the relative humidity conditions for changing the dehumidification capacity in dehumidifying operation, can also be set arbitrarily.

[0069] Next, the operation of the operation switching control process according to this embodiment will be described with reference to Fig. 7. Fig. 7 is a flowchart showing an example of the operation switching control process according to this embodiment.

[0070] (Step S201) The control unit 40 acquires the set temperature and set humidity set by the operation unit 30 from the operation unit 30. The control unit 40 also acquires the detected temperature detected by the temperature sensor 8 from the temperature sensor 8, and acquires the detected humidity detected by the humidity sensor 9 from the humidity sensor 9. The control unit 40 then acquires the temperature difference (ΔT) between the set temperature set by the operation unit 30 and the detected temperature detected by the temperature sensor 8. The control unit 40 also acquires the humidity difference (relative humidity) between the set humidity set by the operation unit 30 and the detected humidity detected by the humidity sensor 9. Then, the process proceeds to step S203.

[0071] (Step S203) The control unit 40 determines whether the temperature difference (ΔT) has not changed. If the control unit 40 determines that the temperature difference (ΔT) has not changed (YES), the process proceeds to step S205. On the other hand, if the control unit 40 determines that the temperature difference (ΔT) has changed (NO), the process proceeds to step S213.

[0072] (Step S205) The control unit 40 determines whether the cooling / dehumidifying switching condition described with reference to Figures 5 and 6 is satisfied, depending on the change in relative humidity. If the control unit 40 determines that the cooling / dehumidifying switching condition is not satisfied (NO), the process proceeds to step S207. On the other hand, if the control unit 40 determines that the cooling / dehumidifying switching condition is satisfied (YES), the process proceeds to step S209.

[0073] (Step S207) The control unit 40 continues the current operating state. For example, if the current operating state is cooling (weak), the control unit 40 continues the cooling operation with cooling (weak). If the current operating state is cooling (medium), the control unit 40 continues the cooling operation with cooling (medium). If the current operating state is cooling (strong), the control unit 40 continues the cooling operation with cooling (strong). Furthermore, if the current operating state is heating (weak), the control unit 40 continues the heating operation with heating (weak). If the current operating state is heating (medium), the control unit 40 continues the heating operation with heating (medium). If the current operating state is heating (strong), the control unit 40 continues the heating operation with heating (strong). Furthermore, if the current operating state is dehumidification (weak), the control unit 40 continues the dehumidification operation with dehumidification (weak). If the current operating state is dehumidification (medium), the control unit 40 continues the dehumidification operation at dehumidification (medium). If the current operating state is dehumidification (strong), the control unit 40 continues the dehumidification operation at dehumidification (strong). Then, the process returns to step S201.

[0074] (Step S209) The control unit 40 determines whether the condition satisfied in step S205 is a condition for switching from cooling to dehumidification (third condition). If the control unit 40 determines that the condition for switching from cooling to dehumidification (third condition) is satisfied (YES), the process proceeds to step S211.

[0075] (Step S211) The control unit 40 switches from cooling operation to dehumidifying operation. For example, the control unit 40 switches from heating operation with cooling (weak) to dehumidifying operation with dehumidifying (weak) (see FIGS. 5 and 6). After switching to dehumidifying operation, the control unit 40 changes the dehumidifying capacity of the dehumidifying operation in accordance with changes in relative humidity (see FIGS. 5 and 6). For example, as described with reference to FIG. 6, the control unit 40 controls the dehumidifying capacity to one of dehumidifying (weak), dehumidifying (medium), and dehumidifying (strong) as the relative humidity increases or decreases. Then, the process returns to step S201.

[0076] On the other hand, in step S209, if the control unit 40 determines that the condition satisfied in step S205 is the condition for switching from dehumidification to cooling (fourth condition) (NO), the control unit 40 proceeds to step S217, where it switches from dehumidification operation to cooling operation (for example, cooling operation at low cooling mode) (see FIGS. 5 and 6 ).Then, the control unit 40 returns to step S201.

[0077] (Step S213) The control unit 40 determines whether the change in temperature difference (ΔT) has satisfied the cooling / heating switching condition described with reference to Fig. 3. If the control unit 40 determines that the cooling / heating switching condition has been satisfied (YES), the process proceeds to step S215. On the other hand, if the control unit 40 determines that the cooling / heating switching condition has not been satisfied (NO), the process proceeds to step S221.

[0078] (Step S215) The control unit 40 determines whether the condition satisfied in step S213 is the condition for switching from heating to cooling (second condition). If the control unit 40 determines that the condition for switching from heating to cooling (second condition) is satisfied (YES), the control unit 40 proceeds to step S217. On the other hand, if the control unit 40 determines that the condition for switching from cooling to heating (first condition) is satisfied (NO), the control unit 40 proceeds to step S291.

[0079] (Step S217) The control unit 40 switches from the heating operation to the cooling operation. For example, the control unit 40 switches from the heating operation (low) to the cooling operation (low) (see FIG. 3). Then, the process returns to step S201.

[0080] (Step S219) The control unit 40 switches from the cooling operation to the heating operation. For example, the control unit 40 switches from the cooling operation with cooling (weak) to the heating operation with heating (weak) (see FIG. 3). Then, the process returns to step S201.

[0081] (Step S221) The control unit 40 determines whether a condition for changing the output power in cooling or heating operation is satisfied due to a change in the temperature difference (ΔT). The output change refers to a change in the cooling capacity, such as cooling (low), cooling (medium), or cooling (high), in cooling operation, or a change in the heating capacity, such as heating (low), heating (medium), or heating (high), in heating operation, as described with reference to FIG. 3 . If the control unit 40 determines that the condition for changing the output power is satisfied due to a change in the temperature difference (ΔT) (YES), the control unit 40 proceeds to step S223. On the other hand, if the control unit 40 determines that the condition for changing the output power is not satisfied even if the temperature difference (ΔT) has changed (NO), the control unit 40 continues the current operating state (step S207). Then, the control unit 40 returns to step S201.

[0082] (Step S223) The control unit 40 changes the output in response to a change in the temperature difference (ΔT). For example, when the control unit 40 is performing cooling operation, the control unit 40 changes the output to one of cooling (weak), cooling (medium), and cooling (strong) in response to a change in the temperature difference (ΔT). When the control unit 40 is performing heating operation, the control unit 40 changes the output to one of heating (weak), heating (medium), and heating (strong) in response to a change in the temperature difference (ΔT). Then, the process returns to step S201.

[0083] As described above, the air conditioning system 1 according to this embodiment is equipped with a humidity sensor 9 that detects humidity within the air conditioning system 1 and further performs dehumidification operation. The operation unit 30 accepts an operation to set a set humidity. The control unit 40 controls switching between cooling operation and heating operation based on changes in the temperature difference (ΔT), and also controls switching between cooling operation and dehumidification operation based on the temperature difference (ΔT) and the relative humidity (an example of a humidity difference) between the set humidity set by the operation unit 30 and the detected humidity detected by the humidity sensor 9.

[0084] This allows the air conditioning system 1 to not only automatically switch between cooling and heating operation in response to changes in the temperature difference (ΔT), but also automatically switch to dehumidification operation in response to the relative humidity, thereby increasing humidity comfort in addition to room temperature.

[0085] For example, the control unit 40 controls switching between cooling operation and dehumidification operation based on the relative humidity when the temperature difference (ΔT) is within a predetermined range, and makes the relative humidity conditions when switching from cooling operation to dehumidification operation different from the relative humidity conditions when switching from dehumidification operation to cooling operation.

[0086] As a result, when the air conditioning system 1 automatically switches between the cooling operation and the dehumidifying operation in accordance with the relative humidity, by providing a difference (differential) between the relative humidity at which the air conditioning operation switches from the dehumidifying operation to the cooling operation and the relative humidity at which the dehumidifying operation switches from the cooling operation to the cooling operation, the air conditioning system 1 can prevent the operating state from becoming unstable when switching between the cooling operation and the dehumidifying operation.

[0087] For example, the humidity sensor 9 is provided in the indoor unit 20. This allows the air conditioning system 1 to detect the actual humidity of the indoor air and appropriately switch between the cooling operation and the humidity operation.

[0088] For example, as shown in Figure 1, by installing a humidity sensor 9 near where the intake duct 6 of the indoor unit 20 is connected, it is possible to detect and control the humidity of the room air sucked in through the intake port 3 (intake humidity), thereby appropriately bringing the humidity in the room close to the set humidity and increasing comfort.

[0089] Furthermore, since the air conditioning system 1 according to this embodiment is a whole-building air conditioning system in which the intakes 3 and exhausts 4 of multiple rooms are connected to the indoor unit 20 by ducts, it is possible to control not only the switching between cooling operation and heating operation but also the switching to humidity operation, thereby making it possible to bring the humidity in all rooms closer to the set humidity to increase comfort and also suppress the occurrence of condensation in the ducts.

[0090] <Third Embodiment> Next, a third embodiment will be described. The operation unit 30 according to this embodiment is a thermostat that is primarily used in North America. The rest of the configuration is the same as that of the first and second embodiments. For example, the operation unit 30 may be a thermostat that has at least a temperature sensor, and may output a control signal that controls the air conditioning system 1 based on the temperature (room temperature) detected by this temperature sensor and the set temperature. Furthermore, the operation unit 30 may have a humidity sensor in addition to the temperature sensor.

[0091] The operation unit 30 may be a remote controller other than a thermostat. The operation unit 30 may be a remote controller other than a thermostat and may have either or both a temperature sensor and a humidity sensor.

[0092] In this way, the operation unit 30 may be a thermostat or a remote control other than a thermostat, and in that case, the same operation switching control as in the first and second embodiments can be performed and the same effects can be achieved. Furthermore, if the operation unit 30 is a thermostat, it is widely used in the North American market, so it can provide comfort to a wide range of users. Furthermore, since the type of operation unit 30 is not important, it can be adjusted to suit the market environment.

[0093] Each embodiment has been described above in detail with reference to the drawings, but the specific configuration is not limited to these embodiments, and it is possible to combine the embodiments, or to modify or omit the embodiments as appropriate.

[0094] In the above embodiment, as shown in Fig. 1, an air conditioning system 1 for central air conditioning has been described as an example in which the inlets 3 and outlets 4 of a plurality of rooms are connected to the indoor unit 20 by ducts, but the present invention is not limited to this. For example, a non-duct type indoor unit 20 that does not use a duct may be provided for each room. In this case, by providing a temperature sensor 8 and a humidity sensor 9 in the indoor unit 20, the indoor temperature can be properly detected, and the room temperature can be brought closer to the set temperature, thereby increasing comfort.

[0095] Furthermore, the operation unit 30 is not limited to a thermostat or a remote control, and may be a smartphone, a tablet PC (Personal Computer), or the like.

[0096] It should be noted that a program for realizing the functions of the control unit 40 may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed to perform the processing of the control unit 40. Note that the term "computer system" here includes hardware such as an OS and peripheral devices.

[0097] Furthermore, "computer-readable recording media" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, "computer-readable recording media" also includes devices that dynamically store programs for a short period of time, such as communication lines used when transmitting programs over networks like the Internet or communication lines like telephone lines, and devices that store programs for a fixed period of time, such as volatile memory within computer systems that serve as servers or clients. The programs may also be programs that implement some of the aforementioned functions, or may be programs that can achieve the aforementioned functions in combination with programs already stored in the computer system. The programs may also be stored on a designated server and distributed (e.g., downloaded) over communication lines in response to requests from other devices.

[0098] Furthermore, some or all of the functions of the control unit 40 may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each function may be individually implemented as a processor, or some or all of the functions may be integrated into a processor. The integrated circuit method is not limited to LSI, and may be implemented using a dedicated circuit or a general-purpose processor. Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology, an integrated circuit based on that technology may be used.

[0099] REFERENCE SIGNS LIST 1 Air conditioning system 3 Intake port 4 Outlet port 5 (5a, 5b) Refrigerant piping 6 Intake duct 7 Outlet duct 8 Temperature sensor 9 Humidity sensor 10 Outdoor unit 13 Compressor 14 Outdoor unit heat exchanger 15 Four-way valve 16 Expansion valve 17 Outdoor unit fan 20 Indoor unit 25 Indoor unit heat exchanger 27 Indoor unit fan 30 Operation unit 40 Control unit

Claims

1. An air conditioning system comprising an outdoor unit having a compressor, an outdoor heat exchanger, and an outdoor fan, an indoor unit having an indoor heat exchanger and an indoor fan, and a refrigerant pipe connecting the outdoor unit and the indoor unit, and performing at least cooling operation or heating operation, An operation unit that receives an operation for setting one common set temperature in the cooling operation and the heating operation, A temperature sensor that detects a temperature in the air conditioning system, A control unit that controls switching between the cooling operation and the heating operation based on a change in the temperature difference between the set temperature set by the operation unit and the detected temperature detected by the temperature sensor, The control unit switches from the cooling operation to the heating operation when the detected temperature after the change when the temperature difference changes in the cooling operation is lower than the set temperature by a predetermined threshold or more as a first condition, When the temperature difference changes in the heating operation, the control unit switches from the heating operation to the cooling operation when the detected temperature after the change is higher than the set temperature by a predetermined threshold or more as a second condition, When the first condition is not satisfied in the cooling operation, the cooling operation is continued, When the second condition is not satisfied in the heating operation, the heating operation is continued. An air conditioning system.

2. The air conditioning system according to claim 1, further comprising a humidity sensor that detects humidity in the air conditioning system and performs a dehumidifying operation, The operation unit receives an operation for setting a set humidity, The control unit controls switching between the cooling operation and the dehumidifying operation based on the humidity difference between the set humidity set by the operation unit and the detected humidity detected by the humidity sensor and the temperature difference, in addition to controlling switching between the cooling operation and the heating operation based on the change in the temperature difference.

3. The control unit controls switching between the cooling operation and the dehumidifying operation based on the humidity difference when the temperature difference is within a predetermined range, and makes the conditions for the humidity difference when switching from the cooling operation to the dehumidifying operation different from the conditions for the humidity difference when switching from the dehumidifying operation to the cooling operation. The air conditioning system according to claim 2.

4. The temperature sensor is provided in the indoor unit. The air conditioning system according to claim 1.

5. The humidity sensor is provided in the indoor unit, and the air conditioning system according to claim 2.

6. The operation unit is a thermostat having the temperature sensor, and the air conditioning system according to claim 1.

7. The operation unit is a thermostat having the humidity sensor, and the air conditioning system according to claim 2.

8. The temperature sensor is provided in the operation unit, and the air conditioning system according to claim 1.

9. The humidity sensor is provided in the operation unit, and the air conditioning system according to claim 2.

10. A control method in an air conditioning system including an outdoor unit having a compressor, an outdoor unit heat exchanger, and an outdoor unit fan, an indoor unit having an indoor unit heat exchanger and an indoor unit fan, and a refrigerant pipe connecting the outdoor unit and the indoor unit, and performing at least a cooling operation or a heating operation, the method including: a step in which an operation unit receives an operation of setting one set temperature common to the cooling operation and the heating operation; a step in which a temperature sensor detects a temperature in the air conditioning system; and a step in which a control unit controls switching between the cooling operation and the heating operation based on a change in a temperature difference between the set temperature set by the operation unit and a detected temperature detected by the temperature sensor, and when the control unit controls switching between the cooling operation and the heating operation, switching from the cooling operation to the heating operation when a first condition that the detected temperature after the change when the temperature difference changes in the cooling operation is lower than a predetermined threshold value with respect to the set temperature is satisfied, switching from the heating operation to the cooling operation when a second condition that the detected temperature after the change when the temperature difference changes in the heating operation is higher than a predetermined threshold value with respect to the set temperature is satisfied, continuing the cooling operation when the first condition is not satisfied in the cooling operation, and continuing the heating operation when the second condition is not satisfied in the heating operation.

Images