Air conditioning device

Abstract

An air conditioning device (10) is provided with a refrigerant circuit (11) including a compressor (21), a condenser (23), an evaporator (31), and an expansion valve (24), and performs cooling such that temperature and humidity in a room reach an indoor temperature target value and an indoor humidity target value, respectively, by means of the evaporator (31). The air conditioning device (10) comprises: a humidity detection means (42) that detects a relative humidity in the room; and a control unit (C) that controls the compressor (21) and the expansion valve (24) on the basis of an evaporation temperature target value of a refrigerant in the evaporator (31). The control unit (C), in a state in which the temperature in the room is in the vicinity of the indoor temperature target value, sets the evaporation temperature target value on the basis of a detected value of the humidity detection means (42) and the indoor humidity target value.

Description

Air conditioner

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

[0002] In the air conditioner described in Patent Document 1, in order to perform sufficient humidity control during cooling operation, the dew point temperature is calculated from the set temperature and the target humidity in the room, and the target value of the evaporation temperature (heat exchanger temperature) is set to be 3 to 4 °C lower than the dew point temperature.

[0003] Patent No. 2909955

[0004] In the air conditioner described in Patent Document 1, the humidity in the room can be kept below the target humidity, but the humidity in the room cannot be accurately adjusted to the target humidity. For this reason, as a result of the operation control of the air conditioner being performed in a state where the humidity in the room is lower than the target humidity, unnecessary energy is required, and moreover, since the followability of the humidity with respect to disturbances and changes in the target humidity is not ensured, there is a problem that comfortable air conditioning cannot be performed.

[0005] An object of the present disclosure is to provide an air conditioner that can improve energy saving while keeping the humidity in the room within a comfortable range.

[0006] A first aspect of the present disclosure is an air conditioner (10) including a refrigerant circuit (11) including a compressor (21), a condenser (23), an evaporator (31), and an expansion valve (24), and performing cooling so that the temperature and humidity in the room become the indoor temperature target value and the indoor humidity target value by the evaporator (31), respectively. The air conditioner includes a humidity detection means (42) for detecting the relative humidity in the room, and a control unit (C) for controlling the compressor (21) and the expansion valve (24) based on the evaporation temperature target value of the refrigerant in the evaporator (31). The control unit (C) sets the evaporation temperature target value based on the detection value of the humidity detection means (42) and the indoor humidity target value in a state where the temperature in the room is near the indoor temperature target value.

[0007] In the first embodiment, the target evaporation temperature is set based on the detected humidity value and the target humidity value when the indoor temperature is near the target indoor temperature value. This makes it possible to maintain the indoor humidity within a comfortable range. Furthermore, since the evaporation temperature is not excessively lowered for dehumidification, it is possible to prevent performance deterioration due to evaporation temperature drops and compressor start / stop, thereby improving energy efficiency.

[0008] A second aspect of the present disclosure is, in the first aspect, the control unit (C) further sets the target evaporation temperature value based on the degree of superheating of the evaporator (31).

[0009] In the second embodiment, since the latent heat capacity can be accurately calculated, the indoor humidity can be precisely adjusted to the indoor humidity target value, thereby improving comfort.

[0010] A third aspect of the present disclosure, in the first or second embodiment, the control unit (C) further sets the evaporation temperature target value based on the currently detected value and the previously detected value.

[0011] In the third embodiment, indoor humidity can be controlled more accurately, thus improving comfort.

[0012] A fourth aspect of the present disclosure further comprises an indoor fan (32) in any one of the first to third aspects, wherein the control unit (C) sets the rotational speed of the indoor fan (32) based on the detected value and the indoor humidity target value.

[0013] In the fourth embodiment, the latent heat capacity can be easily adjusted, making it easier to match the indoor humidity to the target humidity.

[0014] A fifth aspect of the present disclosure is that in any one of the first to fourth aspects, the evaporators (31) are arranged in a plurality of chambers, and the control unit (C) sets an evaporation temperature target value for each of the evaporators (31) arranged in the plurality of chambers, and controls the compressor (21) and the expansion valve (24) based on the minimum, average, or median value of the set evaporation temperature target value.

[0015] In the fifth embodiment, energy efficiency can be improved while maintaining the humidity levels in multiple rooms within a comfortable range.

[0016] A sixth aspect of the present disclosure is that, in any one of the first to fourth aspects, the control unit (C) does not use the detected value to set the evaporation temperature target value if the detected value changes beyond a predetermined range during a predetermined time.

[0017] In the sixth embodiment, if a sudden change in the humidity detection value occurs due to an abnormality in the humidity detection means (42) or water adhesion, stable humidity control can be performed by ignoring the change.

[0018] A seventh aspect of the present disclosure is that, in any one of the first to sixth aspects, the control unit (C) calculates a first evaporation temperature target value based on the detected value and the indoor humidity target value, calculates a second evaporation temperature target value based on the indoor temperature and the indoor temperature target value, and sets the second evaporation temperature target value to the evaporation temperature target value if the second evaporation temperature target value is lower than the first evaporation temperature target value.

[0019] In the seventh embodiment, it is possible to maintain the indoor humidity within a comfortable range while keeping the indoor temperature near the target indoor temperature value.

[0020] An eighth aspect of this disclosure is that in any one of the first to fourth aspects, the target indoor humidity value is within the range of 40% to 60%.

[0021] In the eighth aspect, it is possible to avoid causing discomfort to people inside the room.

[0022] Figure 1 is a refrigerant circuit diagram of the air conditioning system of the embodiment. Figure 2 is a flow diagram of the air conditioning control of the embodiment. Figure 3(a) shows the changes in room temperature, humidity, and compressor start / stop using conventional air conditioning control, and Figure 3(b) shows the changes in room temperature, humidity, and compressor start / stop using the air conditioning control of the embodiment. Figure 4 is a flow diagram of the air conditioning control of Modification 1. Figure 5 is a flow diagram of the air conditioning control of Modification 2. Figure 6 is a flow diagram of the air conditioning control of Modification 3. Figure 7 is a flow diagram of the air conditioning control of Modification 4. Figure 8 is a flow diagram of the air conditioning control of Modification 5.

[0023] Embodiments of this disclosure will be described below with reference to the drawings. The following embodiments are essentially preferred examples and are not intended to limit the scope of the invention, its applications, or its uses. In the drawings, the same reference numerals represent the same components, but the dimensions on the drawings, such as length, width, thickness, and depth, have been appropriately changed from the actual scale for clarity and simplification of the drawings and may not correspond to the actual relative dimensions.

[0024] <Air Conditioning System> In the air conditioning system (10) of this embodiment shown in Figure 1, one indoor unit (30) is connected to one outdoor unit (20) to form a refrigerant circuit (11).

[0025] The outdoor unit (20) includes a compressor (21), a four-way switching valve (22), an outdoor heat exchanger (23), and an expansion valve (24). The compressor (21) has a motor (25) whose frequency can be variably adjusted by an inverter, thereby configuring the capacity of the compressor (21) to be variable. The four-way switching valve (22) switches the flow path as shown by the solid line in the figure during cooling operation and as shown by the dashed line in the figure during heating operation. The outdoor heat exchanger (23) is a heat source side heat exchanger and functions as a condenser during cooling operation and as an evaporator during heating operation. The outdoor heat exchanger (23) is equipped with an outdoor fan (26), which is a heat source side fan. The outdoor fan (26) is driven by a motor (27) whose rotational speed can be variably adjusted by an inverter, thereby configuring the airflow of the outdoor fan (26) to be variable. The expansion valve (24) constitutes an expansion mechanism for reducing the pressure of the refrigerant, and may be, for example, an electrically operated expansion valve.

[0026] The indoor unit (30) has an indoor heat exchanger (31). The indoor heat exchanger (31) is a user-side heat exchanger and functions as an evaporator during cooling operation and as a condenser during heating operation. The indoor heat exchanger (31) is provided with an indoor fan (32), which is a user-side fan. The indoor fan (32) is driven by a motor (33) whose rotational speed is variably adjusted by an inverter, thereby configuring the airflow of the indoor fan (32) to be variable. Temperature detection means (41) and humidity detection means (42) are provided in the air passage of the indoor fan (32). The temperature detection means (41) detects the dry-bulb temperature of the indoor air and is composed of, for example, a temperature sensor. The humidity detection means (42) detects the relative humidity of the indoor air and is composed of, for example, a relative humidity sensor. The indoor heat exchanger (31) is provided with evaporation temperature detection means (43) that detects the evaporation temperature of the refrigerant when it functions as an evaporator. The evaporation temperature detection means (43) is composed of, for example, a temperature sensor.

[0027] In the air conditioning system (10) of this embodiment shown in Figure 1, the compressor (21), the four-way diverter valve (22), the outdoor heat exchanger (23), the expansion valve (24), and the indoor heat exchanger (31) are connected in order by refrigerant piping (12) to form a refrigerant circuit (11). The refrigerant circuit (11) is configured to be switchable between cooling operation and heating operation by the four-way diverter valve (22).

[0028] The air conditioning system (10) includes a control unit (C) that controls the operation of the air conditioning system (10). A temperature detection means (41), a humidity detection means (42), and an evaporation temperature detection means (43) are connected to the input side of the control unit (C). A compressor (21), an expansion valve (24), a motor (27) for the outdoor fan (26), and a motor (33) for the indoor fan (32) are connected to the output side of the control unit (C).

[0029] The control unit (C) is composed of, for example, a computer and its peripheral devices. The control unit (C) performs the functions described later by hardware such as a computer and programs executed by that computer. The control unit (C) includes a remote controller (hereinafter referred to as a remote control) for the user to operate the air conditioning unit (10).

[0030] <Air Conditioning Control> In this embodiment, the cooling operation control will be described in detail. In air conditioning control, there is an optimal evaporation temperature for both sensible heat load and latent heat load. When the air conditioning capacity is kept constant, increasing the evaporation temperature and airflow rate leads to energy savings. However, if the airflow rate is increased too much, the power consumption of the fan will increase. Also, if the evaporation temperature is raised too high, the latent heat capacity decreases and dehumidification will not occur, so if the evaporation temperature is raised too high, comfort will deteriorate.

[0031] In the cooling operation of the air conditioning system (10), the control unit (C) controls the compressor (21) and the expansion valve (24) in the refrigerant circuit (11), which consists of a compressor (21), an outdoor heat exchanger (23), an indoor heat exchanger (31), and an expansion valve (24), based on the target evaporation temperature of the refrigerant in the indoor heat exchanger (31), which functions as an evaporator. This allows the indoor heat exchanger (31) (evaporator) to perform cooling so that the indoor temperature and humidity reach the target indoor temperature and indoor humidity values, respectively.

[0032] In this embodiment, in order to improve energy efficiency while maintaining indoor humidity within a comfortable range, the control unit (C) sets an evaporation temperature target value based on the value detected by the humidity detection means (42) and the indoor humidity target value when the indoor temperature is near the indoor temperature target value. Here, "near" means a range of about ±2°C, preferably a range of about ±1.5°C, more preferably a range of about ±1.0°C, and even more preferably a range of about ±0.5°C.

[0033] The air conditioning control in this example will be explained below, referring to the flowchart in Figure 2.

[0034] First, in step S01, the control unit (C) determines whether "cooling operation" is turned ON on the remote control. If it is turned ON, in step S02, the control unit (C) obtains the indoor humidity target value (humidity target value RhS). The indoor humidity target value is basically a fixed value, but if mode selection such as "dehumidification mode" or "humidification mode" is possible, the indoor humidity target value may differ depending on the selected mode. Note that the control from step S02 onward will not start unless "cooling operation" is turned ON on the remote control.

[0035] Following step S02, in step S03, the control unit (C) performs a thermo-on determination. In the thermo-on determination, the control unit (C) determines whether the relationship "Tr > Trs + α" holds true, where Tr is the room temperature detected by the temperature detection means (41), Trs is the target room temperature, and α is the thermo-on / off interval. The thermo-on / off interval α is, for example, about 2°C, preferably about 1.5°C, more preferably about 1.0°C, and even more preferably about 0.5°C.

[0036] If "Tr > Trs + α", the control unit (C) starts the compressor (21) in step S04 to turn the air conditioner (10) thermostat on, and performs normal startup control in step S05. On the other hand, if "Tr > Trs + α" is not true, the control unit (C) stops the compressor (21) in step S11 to turn the air conditioner (10) thermostat off, and returns to step S01.

[0037] In the startup control of step S05, the rotational speed of the compressor (21), the airflow of the indoor fan (32), etc., are adjusted to bring the indoor temperature closer to the target indoor temperature. The rotational speed of the compressor (21) is set based on the target evaporation temperature of the refrigerant in the indoor heat exchanger (31), which functions as an evaporator. The airflow of the indoor fan (32) is set based on the indoor temperature, the target indoor temperature, the difference between the indoor temperature and the target indoor temperature, the indoor humidity (relative humidity), the target indoor humidity, and the difference between the indoor humidity and the target indoor humidity. To save energy, it is preferable to make the airflow of the indoor fan (32) as large as possible, but once the indoor temperature approaches the target indoor temperature, the airflow of the indoor fan (32) may be reduced to stabilize the indoor temperature.

[0038] Following step S05, in step S06, the control unit (C) performs a thermo-off determination. The thermo-off determination determines whether the relationship "Tr (room temperature) < Trs (target room temperature) - α (thermo-on / off interval)" holds true.

[0039] If "Tr < Trs - α", the control unit (C) stops the compressor (21) in step S11, puts the air conditioner (10) into a thermo-off state, and returns to step S01. On the other hand, if "Tr < Trs - α" is not true, the control unit (C) performs the humidity control in steps S07 to S10, which will be described later, and then returns to the thermo-off determination in step S06. In other words, the humidity control in steps S07 to S10 is repeated until it is determined in step S06 that the relationship "Tr < Trs - α" holds true. As a result, the control in steps S07 to S10 is performed when the indoor temperature is near the indoor temperature target value.

[0040] In step S07, the control unit (C) obtains the detected value (indoor humidity Rh) from the humidity detection means (42). In step S08, it calculates the difference (humidity difference eRh = Rh - Rhs) between the indoor humidity Rh and the humidity target value RhS obtained in step S02. In step S09, it calculates the evaporation temperature target value (TeS = f(Rh, eRh)) based on the indoor humidity Rh and the humidity difference eRh. That is, the control unit (C) calculates the evaporation temperature target value based on the detected value from the humidity detection means (42) and the indoor humidity target value when the indoor temperature is near the indoor temperature target value. In step S09, neither the indoor temperature target value nor the indoor temperature is used in the calculation of the evaporation temperature target value TeS. Details of the calculation of the evaporation temperature target value TeS in step S09 will be described later.

[0041] Following step S09, in step S10, the control unit (C) controls the compressor (21), expansion valve (24), and indoor fan (32) so that the evaporation temperature Te becomes the target evaporation temperature TeS calculated in step S09, and then returns to step S06. In step S10, the higher the evaporation temperature Te is than the target evaporation temperature TeS, the more the control unit (C) increases the rotational speed of the compressor (21) in order to reduce the evaporation temperature Te significantly.

[0042] <Calculation of the target evaporation temperature> The method for calculating the target evaporation temperature in step S09 of Figure 2 will be described in detail below.

[0043] The control unit (C) calculates the target evaporation temperature for changing the latent heat capacity of the air conditioner (10) so that the indoor humidity approaches the indoor humidity target value, using the indoor humidity (relative humidity), the indoor humidity target value, the difference between the indoor humidity and the indoor humidity target value, together with the evaporation temperature, the superheat degree of the evaporator (indoor heat exchanger (31)), the air volume (the air volume of the indoor fan (32)), the indoor temperature, etc. For example, when the indoor humidity is higher than the indoor humidity target value (when dehumidification is desired), the latent heat capacity is made larger than the latent heat load, and when the indoor humidity is about the same as the indoor humidity target value (when the humidity is to be stabilized), the latent heat capacity is made about the same as the latent heat load. Here, the latent heat capacity is calculated from the evaporation temperature, the superheat degree of the evaporator, and the air volume, and the latent heat load is calculated from the change amount of the indoor humidity. In other words, the indoor humidity changes according to the difference between the latent heat load and the latent heat capacity.

[0044] Using the indoor humidity (indoor humidity Rh) detected by the humidity detection means (42), the indoor humidity target value (humidity target value RhS), and the difference (humidity difference eRh = Rh - Rhs) between the indoor humidity Rh and the humidity target value RhS, the target evaporation temperature TeS can be calculated by various methods.

[0045] For example, the target evaporation temperature TeS may be calculated using the calculation formula of position-type PID control "TeS = f(eRh) = Kp×eRh + Ki×∫eRh·dt + Kd×d(eRh) / dt", or the calculation formulas of velocity-type PID control "ΔTeS = Kp×eRh + Ki×∫eRh·dt + Kd×d(eRh) / dt" and "TeS = TeS at the previous time + ΔTeS". Here, the PID parameters Kp, Ki, and Kd are the proportional constant, the integral constant, and the differential constant, respectively. Also, the initial value of TeS for velocity-type PID control may be, for example, a temperature 5°C lower than the indoor temperature target value.

[0046] Also, instead of the calculation formula of PID control, the calculation formula of PI control "Tes (or ΔTeS) = Kp×eRh + Ki×∫eRh·dt", the calculation formula of PD control "Tes (or ΔTeS) = Kp×eRh + Kd×d(eRh) / dt", or the calculation formula of P control "Tes (or ΔTeS) = Kp×eRh" may be used.

[0047] Alternatively, instead of the above feedback control, evaporation temperature target values TeS corresponding to various combinations of indoor humidity Rh and humidity difference eRh may be tabulated in advance (TeS = table(Rh, eRh)).

[0048] The tables of control parameters (Kp, Ki, Kd) and evaporation temperature target value TeS are set in advance so that air operation with high responsiveness to follow the evaporation temperature target value TeS and suppression of excessive overshoot and hunting is possible. The control parameters may be variably set according to the level of indoor humidity Rh.

[0049] Alternatively, without using feedback control or a table, the latent heat load (Llat = f1(Rh)) is calculated from the indoor humidity Rh, the required latent heat capacity (f2(eRh, Llat)) is calculated from the latent heat load Llat and the humidity difference eRh, and the evaporation temperature target value TeS may be determined so that the latent heat capacity (f3(TeS)) = the required latent heat capacity.

[0050] <Embodiment Features> In the air conditioner (10) of this embodiment, an evaporation temperature target value is set based on the detected value of the indoor humidity and the indoor humidity target value in a state where the indoor temperature is near the indoor temperature target value. Therefore, the indoor humidity and temperature can be kept within a comfortable range. Also, since air conditioning control can be performed so that the indoor humidity does not fall below the indoor humidity target value, the evaporation temperature is not excessively lowered for dehumidification, so performance degradation associated with a decrease in evaporation temperature and compressor shutdown can be prevented, and energy efficiency can be improved. Furthermore, since unnecessary dehumidification is not performed, health hazards and furniture deterioration caused by indoor drying can be prevented.

[0051] By the way, in conventional air conditioning control, when the indoor humidity exceeds 60%, the evaporation temperature target value is rapidly decreased, so the capacity of the compressor (21) may become excessive and shutdown may occur. As a result, for example, as shown in Fig. 3(a), both the humidity and the room temperature become unstable, and the compressor repeats shutdown operations (intermittent operation).

[0052] In contrast, the air conditioning system (10) of this embodiment can accurately and quickly adjust the indoor humidity to the target indoor humidity value by, for example, feedback control based on the humidity difference eRh mentioned above, and can also gradually change the target evaporation temperature value according to the indoor humidity. As a result, as shown in Figure 3(b), for example, both humidity and room temperature are stable, and continuous operation of the compressor (21) becomes possible.

[0053] <Modification 1> In the air conditioning control of Modification 1 shown in Figure 4, first, steps S01 to S06 are performed in the same manner as the air conditioning control of the embodiment shown in Figure 2. Note that in Figure 4, the same step numbers are used for steps that are the same as those in the embodiment shown in Figure 2.

[0054] If it is determined in step S06 that the relationship "Tr (indoor temperature) < Trs (target indoor temperature) - α (thermo on / off range)" holds true, then in step S11, the compressor (21) is stopped and the air conditioning system (10) is set to the thermo off state, and the process returns to step S01.

[0055] If it is determined in step S06 that the relationship "Tr (room temperature) < Trs (target room temperature) - α (thermo on / off range)" does not hold, the control unit (C) performs the humidity control described in steps S21, S08, S22-S24, and S10, and then returns to the thermo off determination in step S06. In other words, the humidity control in steps S21, S08, S22-S24, and S10 is repeated until it is determined in step S06 that the relationship "Tr < Trs - α" holds. As a result, the control in steps S21, S08, S22-S24, and S10 is performed when the room temperature is near the target room temperature.

[0056] In step S21, the control unit (C) obtains the detected value (indoor humidity Rh) from the humidity detection means (42) and the superheating degree SH of the evaporator (indoor heat exchanger (31)). The superheating degree SH is calculated by subtracting the detected value from the evaporation temperature detection means (43) from the intake gas temperature of the compressor (21).

[0057] Next, in step S08, the control unit (C) calculates the difference between the indoor humidity Rh and the humidity target value RhS obtained in step S02 (humidity difference eRh = Rh - Rhs). Then, in step S22, it calculates the latent heat load (Llat = f1(Rh)) from the indoor humidity Rh, and in step S23, it calculates the required latent heat capacity (f2(eRh,Llat)) from the latent heat load Llat and the humidity difference eRh.

[0058] Next, in step S24, the control unit (C) calculates the target evaporation temperature TeS based on the superheating degree SH obtained in step S21, such that the latent heat capacity (f3(TeS,SH)) = required latent heat capacity.

[0059] Following step S24, in step S10, the control unit (C) controls the compressor (21), expansion valve (24), and indoor fan (32) so that the evaporation temperature Te becomes the target evaporation temperature TeS calculated in step S24, and then returns to step S06.

[0060] According to the modified example 1 described above, in addition to the same effects as the embodiment described above, the following effects can be obtained. That is, the control unit (C) sets an evaporation temperature target value based on the indoor humidity and the indoor humidity target value, as well as the degree of superheating of the indoor heat exchanger (31). As a result, the latent heat capacity can be accurately calculated, and the indoor humidity can be accurately adjusted to the indoor humidity target value, thereby improving comfort.

[0061] <Modification 2> In the air conditioning control of Modification 2 shown in Figure 5, first, steps S01 to S06 are performed in the same manner as in the air conditioning control of the embodiment shown in Figure 2. Note that in Figure 5, the same step numbers are used for steps that are the same as in the embodiment shown in Figure 2.

[0062] If it is determined in step S06 that the relationship "Tr (indoor temperature) < Trs (target indoor temperature) - α (thermo on / off range)" holds true, then in step S11, the compressor (21) is stopped and the air conditioning system (10) is set to the thermo off state, and the process returns to step S01.

[0063] If it is determined in step S06 that the relationship "Tr (room temperature) < Trs (target room temperature) - α (thermo on / off range)" does not hold, the control unit (C) performs the humidity control described in steps S07, S08, S31-S34, and S10, and then returns to the thermo off determination in step S06. In other words, the humidity control in steps S07, S08, S31-S34, and S10 is repeated until it is determined in step S06 that the relationship "Tr < Trs - α" holds. As a result, the control in steps S07, S08, S31-S34, and S10 is performed when the room temperature is near the target room temperature.

[0064] In step S07, the control unit (C) obtains the detected value (indoor humidity Rh) from the humidity detection means (42), and then in step S08, calculates the difference (humidity difference eRh = Rh - Rhs) between the indoor humidity Rh and the humidity target value RhS obtained in step S02.

[0065] Next, in step S31, the control unit (C) calculates the time change ΔRh of the indoor humidity. ΔRh is the difference between the detected value Rh currently detected by the humidity detection means (42) and the detected value Rh previously detected by the humidity detection means (42) (for example, the detected value Rh N (where N is an integer greater than or equal to 1) time ago).

[0066] Next, in step S32, the control unit (C) calculates the latent heat load (Llat=f1(Rh,ΔRh)) from the indoor humidity Rh and ΔRh, in step S33, the required latent heat capacity (f2(eRh,Llat)) from the latent heat load Llat and the humidity difference eRh, and in step S34, the target evaporation temperature value TeS is calculated such that the latent heat capacity (f3(TeS)) = required latent heat capacity.

[0067] Following step S34, in step S10, the control unit (C) controls the compressor (21), expansion valve (24), and indoor fan (32) so that the evaporation temperature Te becomes the target evaporation temperature TeS calculated in step S34, and then returns to step S06.

[0068] According to the modified example 2 described above, in addition to the same effects as the embodiment described above, the following effects can be obtained. That is, the control unit (C) sets the target evaporation temperature value based on the time change of the indoor humidity in addition to the indoor humidity, so that the indoor humidity can be controlled more accurately, and thus comfort is improved.

[0069] <Modification 3> In the air conditioning control of Modification 3 shown in Figure 6, first, steps S01 to S06 are performed in the same manner as the air conditioning control of the embodiment shown in Figure 2. Note that in Figure 6, the same step numbers are used for steps that are the same as those in the embodiment shown in Figure 2.

[0070] If it is determined in step S06 that the relationship "Tr (indoor temperature) < Trs (target indoor temperature) - α (thermo on / off range)" holds true, then in step S11, the compressor (21) is stopped and the air conditioning system (10) is set to the thermo off state, and the process returns to step S01.

[0071] If it is determined in step S06 that the relationship "Tr (room temperature) < Trs (target room temperature) - α (thermo on / off range)" does not hold, the control unit (C) performs the humidity control described in steps S07, S08, and S41-S44, and then returns to the thermo off determination in step S06. In other words, the humidity control in steps S07, S08, and S41-S44 is repeated until it is determined in step S06 that the relationship "Tr < Trs - α" holds. As a result, the control in steps S07, S08, and S41-S44 is performed when the room temperature is near the target room temperature.

[0072] In step S07, the control unit (C) obtains the detected value (indoor humidity Rh) from the humidity detection means (42), and then in step S08, calculates the difference (humidity difference eRh = Rh - Rhs) between the indoor humidity Rh and the humidity target value RhS obtained in step S02.

[0073] Next, in step S41, the control unit (C) calculates the latent heat load (Llat=f1(Rh)) from the indoor humidity Rh, in step S42, the required latent heat capacity (f2(eRh,Llat)) from the latent heat load Llat and the humidity difference eRh, and in step S43, the control unit (C) calculates the target evaporation temperature TeS and the indoor fan speed Fr so that the latent heat capacity (f3(TeS,Fr)) = required latent heat capacity.

[0074] Following step S43, in step S44, the control unit (C) controls the compressor (21) and expansion valve (24) so ​​that the evaporation temperature Te becomes the target evaporation temperature TeS calculated in step S43, and also controls the rotation speed of the indoor fan (32) to the indoor fan rotation speed Fr calculated in step S43, and then returns to step S06.

[0075] According to the modified example 3 described above, in addition to the same effects as the embodiment described above, the following effects can be obtained. That is, since the control unit (C) sets the rotation speed of the indoor fan (32) based on the indoor humidity and the indoor humidity target value, the latent heat capacity can be easily adjusted, making it easy to adjust the indoor humidity to the target humidity.

[0076] In modification 3, the indoor fan speed was made variable, but instead, the indoor fan speed may be fixed and used as a parameter when calculating the target evaporation temperature in step S43.

[0077] <Modification 4> The air conditioning control of this example will be explained below with reference to the flowchart in Figure 7. In Figure 7, the same step numbers are used for steps that are the same as those in the embodiment shown in Figure 2.

[0078] First, in step S01, the control unit (C) determines whether "cooling operation" is turned ON on the remote control. If it is turned ON, in step S02, the control unit (C) obtains the indoor humidity target value (humidity target value RhS). The indoor humidity target value is basically a fixed value, but if mode selection such as "dehumidification mode" or "humidification mode" is possible, the indoor humidity target value may differ depending on the selected mode. Note that the control from step S02 onward will not start unless "cooling operation" is turned ON on the remote control.

[0079] Following step S02, in step S51, the control unit (C) acquires the indoor temperature target value (room temperature target value TrS). The indoor temperature target value is, for example, the temperature set by the user using the remote control.

[0080] Next, in step S52, the control unit (C) obtains the detected value (room temperature Tr) from the temperature detection means (41) and the detected value (indoor humidity Rh) from the humidity detection means (42), and then in step S03, it performs a thermo-on determination. In the thermo-on determination, the control unit (C) determines whether the relationship "Tr > Trs + α" holds true, with the thermo-on / off width being α. The thermo-on / off width α is the same as in the above embodiment.

[0081] If "Tr > Trs + α", the control unit (C) starts the compressor (21) in step S04 to turn the air conditioner (10) thermostat on, and performs normal startup control in step S05. The startup control in step S05 is the same as in the above embodiment. On the other hand, if "Tr > Trs + α" is not true, the control unit (C) stops the compressor (21) in step S11 to turn the air conditioner (10) thermostat off, and returns to step S01.

[0082] Following step S05, in step S06, the control unit (C) performs a thermo-off determination. The thermo-off determination determines whether the relationship "Tr (room temperature) < Trs (target room temperature) - α (thermo-on / off interval)" holds true.

[0083] If "Tr < Trs - α", the control unit (C) stops the compressor (21) in step S11, puts the air conditioner (10) into a thermo-off state, and returns to step S01. On the other hand, if "Tr < Trs - α" is not true, the control unit (C) performs the humidity control in steps S53, S08, S54-S57, and S10, which will be described later, and then returns to the thermo-off determination in step S06. In other words, the humidity control in steps S53, S08, S54-S57, and S10 is repeated until it is determined in step S06 that the relationship "Tr < Trs - α" holds true. As a result, the control in steps S53, S08, S54-S57, and S10 is performed when the indoor temperature is near the indoor temperature target value.

[0084] In step S53, the control unit (C) obtains the detected value (room humidity Rh) from the humidity detection means (42) and the detected value (room temperature Tr) from the temperature detection means (41). Then, in step S08, it calculates the difference between the room humidity Rh and the humidity target value RhS obtained in step S02 (humidity difference eRh = Rh - Rhs). In step S54, it calculates the difference between the room temperature Tr and the room temperature target value TrS obtained in step S51 (room temperature difference eTr = Tr - Trs).

[0085] Next, in step S55, the control unit (C) calculates a first evaporation temperature target value (TeS1 = f(Rh,eRh)) based on the indoor humidity Rh and the humidity difference eRh, and then in step S56, calculates a second evaporation temperature target value (TeS2 = f(Tr,eTr)) based on the room temperature Tr and the room temperature difference eTr. The calculation of the first evaporation temperature target value TeS1 in step S55 is performed using the same method as the calculation of the evaporation temperature target value TeS in step S09 of the above embodiment. The calculation of the second evaporation temperature target value TeS2 in step S56 is performed as follows.

[0086] The control unit (C) calculates a target evaporation temperature (second target evaporation temperature) for changing the cooling sensible heat capacity of the air conditioner (10) so that the indoor temperature approaches the target indoor temperature, using the indoor temperature, the target indoor temperature, the difference between the indoor temperature and the target indoor temperature, along with the evaporation temperature, the superheating degree of the evaporator (indoor heat exchanger (31)), the airflow rate (airflow rate of the indoor fan (32)), etc. For example, if the indoor temperature is higher than the target indoor temperature (when you want to lower the room temperature), the sensible heat capacity is made greater than the sensible heat load, and if the indoor temperature is about the same as the target indoor temperature (when you want to stabilize the room temperature), the sensible heat capacity is made about the same as the sensible heat load. Here, the sensible heat capacity is calculated from the evaporation temperature, the superheating degree of the evaporator, and the airflow rate, and the sensible heat load is calculated from the change in indoor temperature. In other words, the indoor temperature changes according to the difference between the sensible heat load and the sensible heat capacity.

[0087] Based on the room temperature (room temperature Tr), the target room temperature (target room temperature TrS), and the difference between room temperature Tr and target temperature TrS (temperature difference eTr = Tr - Trs) detected by the temperature detection means (41), the second evaporation temperature target value TeS2 can be calculated using methods such as feedback control or tables as described in the above embodiment.

[0088] Following steps S55 and S56, in step S57, the control unit (C) adopts the smaller of the first evaporation temperature target value TeS1 calculated in step S55 and the second evaporation temperature target value TeS2 calculated in step S56 as the evaporation temperature target value TeS. As a result, if the second evaporation temperature target value TeS2 is lower than the first evaporation temperature target value TeS1, the second evaporation temperature target value TeS2 is set as the evaporation temperature target value TeS. Also, if the second evaporation temperature target value TeS2 is higher than the first evaporation temperature target value TeS1, the first evaporation temperature target value TeS1 is set as the evaporation temperature target value TeS.

[0089] Following step S57, in step S10, the control unit (C) controls the compressor (21), expansion valve (24), and indoor fan (32) so that the evaporation temperature Te becomes the target evaporation temperature TeS set in step S57, and then returns to step S06.

[0090] According to the modified example 4 described above, in addition to the same effects as in the above embodiment, the following effects can be obtained. That is, the control unit (C) sets the smaller of the first evaporation temperature target value based on the indoor humidity detection value and the indoor humidity target value, and the second evaporation temperature target value based on the indoor temperature detection value and the indoor temperature target value, as the evaporation temperature target value. This makes it possible to maintain the indoor humidity within a comfortable range while adjusting the indoor temperature to the indoor temperature target value.

[0091] <Modification 5> The differences between the air conditioning control of Modification 2 shown in Figure 8 and the air conditioning control of the embodiment shown in Figure 2 are as follows. In the embodiment, in step S02, the control unit (C) acquires the indoor humidity target value (humidity target value RhS). In contrast, in this Modification 5, instead of step S02, in step S61, the humidity target value RhS is set to a range of 40% to 60% (comfort range). Steps S03 to S11 following step S61 are the same as in the embodiment.

[0092] According to Modification 5, in addition to the same effects as the above embodiment, the effect of avoiding discomfort for people in the room can be obtained.

[0093] (Other Embodiments) In the above embodiment (including modified examples; the same applies hereinafter), the air conditioning system (10) was configured such that one indoor unit (30) was connected to one outdoor unit (20). However, instead, a configuration in which multiple indoor units (30) are connected to one outdoor unit (20) is also possible. In other words, multiple evaporators (31) may be placed in each of the multiple rooms. In this case, the control unit (C) may set an evaporation temperature target value for each of the multiple evaporators (31) placed in the multiple rooms, and control the compressor (21) and expansion valve (24) of the outdoor unit (20) based on the minimum, average, or median value of the set evaporation temperature target values ​​(multiple).

[0094] Furthermore, considering that the humidity detection value may change rapidly due to abnormalities in the humidity detection means (42) or water adhesion, the control unit (C) may be configured not to use the detected value of the humidity detection means (42) in setting the evaporation temperature target value if the detected value changes beyond a predetermined range within a predetermined time. For example, even under high latent heat load conditions, the relative humidity increases by about 2% per minute, so if a humidity change of 20% / minute or more, which is 10 times that rate of change, is detected, it may be excluded from the humidity control by the control unit (C) described in the above embodiment.

[0095] Although embodiments have been described above, the embodiments can be combined or substituted as appropriate, allowing for diverse changes in form and details. Furthermore, the designations "first," "second," "third," etc., in the specification and claims are used to distinguish the phrases to which these designations are attached, and do not limit the number or order of such phrases.

[0096] As described above, this disclosure is useful for air conditioning systems.

[0097] 10 Air conditioning system 11 Refrigerant circuit 21 Compressor 23 Outdoor heat exchanger (condenser) 24 Expansion valve 31 Indoor heat exchanger (evaporator) 32 Indoor fan 42 Humidity detection means C Control unit

Claims

1. An air conditioning system (10) comprising a refrigerant circuit (11) including a compressor (21), a condenser (23), an evaporator (31), and an expansion valve (24), wherein the evaporator (31) cools the room so that the room temperature and humidity reach target room temperature and target room humidity values, respectively, comprising: a humidity detection means (42) for detecting the relative humidity in the room; and a control unit (C) for controlling the compressor (21) and the expansion valve (24) based on a target evaporation temperature value of the refrigerant in the evaporator (31), wherein the control unit (C) sets the target evaporation temperature value based on the value detected by the humidity detection means (42) and the target room humidity value when the room temperature is near the target room temperature value.

2. An air conditioning system (10) according to claim 1, wherein the control unit (C) further sets the target evaporation temperature value based on the degree of superheating of the evaporator (31).

3. An air conditioning system (10) according to claim 1 or 2, wherein the control unit (C) further sets the target evaporation temperature value based on the currently detected value and the previously detected value.

4. An air conditioning device (10) according to any one of claims 1 to 3, further comprising an indoor fan (32), wherein the control unit (C) sets the rotation speed of the indoor fan (32) based on the detected value and the indoor humidity target value.

5. An air conditioning system (10) according to any one of claims 1 to 4, wherein the evaporators (31) are arranged in a plurality of rooms, and the control unit (C) sets an evaporation temperature target value for each of the evaporators (31) arranged in the plurality of rooms, and controls the compressor (21) and the expansion valve (24) based on the minimum, average, or median value of the set evaporation temperature target value.

6. An air conditioning system (10) according to claim 1, wherein the control unit (C) does not use the detected value to set the evaporation temperature target value if the detected value changes beyond a predetermined range during a predetermined time.

7. An air conditioning system (10) according to any one of claims 1 to 6, wherein the control unit (C) calculates a first evaporation temperature target value based on the detected value and the indoor humidity target value, calculates a second evaporation temperature target value based on the indoor temperature and the indoor temperature target value, and sets the second evaporation temperature target value to the evaporation temperature target value if the second evaporation temperature target value is lower than the first evaporation temperature target value.

8. An air conditioning system (10) according to any one of claims 1 to 7, wherein the target indoor humidity value is within the range of 40% or more and 60% or less.

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