JPH01222137A - Air conditioning device - Google Patents

Abstract

PURPOSE:To stabilize the room humidity and temperature in an object area with a high degree of control accuracy, by regulating the lift of an electronic expansion valve corresponding to the room humidity and temperature in the area. CONSTITUTION:When the room temperature detected by a room temperature detector 9 is higher than a set temperature and the differential temperature exceeds a specified differential temperature, No.1 temperature control device 15 regulates the lift of No.1 electronic expansion valve 3 in proportion to the differential temperature DELTAT at that time. When the differential temperature DELTAT is within the specified differential temperature and a humidity detector 10 indicates a value of the room humidity exceeding a specified differential humidity, a re-heat quantity control device 17 regulates No.2 electronic expansion valve 6 to open to a lift in proportion to the differential humidity DELTARH in case the room humidity is higher than the specified humidity, and to close to a lift in proportion to the differential humidity DELTARH in case the room humidity lower than the specified humidity. When the differential humidity DELTARH is within the specified differential humidity and the differential temperature DELTAT exceeds the specified differential temperature, No.2 temperature control device 16 regulates No.2 electronic expansion valve 6 to close to a lift in proportion to the differential temperature DELTAT in case the room temperature is higher than the specified temperature, and to open to a lift in proportion to the differential temperature in case the room temperature is lower than the specified temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an air conditioner suitable for maintaining a constant temperature throughout the year, such as in a computer room.

(Prior art) As this type of constant temperature/constant temperature device, for example,
There is a system disclosed in Japanese Patent No. 9744, which is widely used for air conditioning in computer rooms, etc., but this is a differential with a temperature of around 2°C between the upper limit ON operating point and the lower limit OFF operating point. and a humidity controller that has a differential of around 10% relative humidity between the upper limit ON operation point and the lower limit OFF operation point. The compressor of the refrigeration system is operated by the signal transmitted at each off operating point, and the signals transmitted at each OFF operating point are issued together to stop the compressor and maintain the temperature and humidity within a predetermined range.

(Problems to be Solved by the Invention) Since the above-mentioned conventional device controls temperature and humidity in steps using an on-off method, the range to be air-conditioned necessarily has a width that is the same as or slightly wider than that of the differential. It is inevitable that there will be a range of changes in temperature and humidity, and therefore the problem is that temperature and humidity control becomes rough.

Although it is theoretically possible to make the difference in the differential as small as possible, in reality, the pressure m
It is difficult to say that this is a practical measure because the frequency of starting and stopping the aircraft increases, which not only has a negative effect on equipment life and running costs, but also causes a hunting phenomenon.

The present invention has been made to address these problems, and it uses an electronic expansion valve with a structure that allows easy and reliable valve opening control in place of the temperature-sensitive expansion valve that has been widely used in the past. By controlling the opening of this electronic expansion valve according to the room temperature and humidity of the target area, continuous stable operation that avoids the start and stop of the compressor is made possible with a simple refrigeration circuit, and at the same time, with high control accuracy. The object of the present invention is to realize a practical device that is stable in temperature and humidity, has a minimum equipment configuration, is economical, and is compact.

(Means for Solving the Problems) Therefore, as is clear with reference to the accompanying drawings, the present invention provides a compressor (1), a condenser (2) provided on the outdoor side, a first electronic expansion valve (3), A refrigerating cycle is formed by an evaporator (4) provided on the indoor side, and a reheater (5) is arranged on the downstream side of the evaporator (4) in the air flow direction. A refrigerant circuit in which the second electronic expansion valve (6) is connected in series is connected in parallel to a refrigerant circuit in which the condenser (2) and the first electronic expansion valve (3) are connected in series, while the evaporator ( 4), a room temperature detector (9) that detects the intake air temperature, and an evaporator (
4) The room temperature measured by the humidity detector 0 [that detects the suction air humidity] and the room temperature detector (9) is higher than the set temperature, and
If the value exceeds the predetermined temperature difference, the first electronic expansion valve (3)
a first temperature control means Q5) that controls the opening to an opening proportional to the temperature difference (ΔT) at that time; and when the temperature difference (ΔT) is within a predetermined temperature difference, the room humidity is set by the humidity detector αω. If the value exceeds a predetermined humidity difference with respect to humidity, when the room humidity is higher, the second electronic expansion valve (6) is opened to an opening proportional to the humidity difference (ΔRH11) at that time, and vice versa. When the humidity is low, the second electronic expansion valve (6) is
H) Reheat amount control means a for closing to an opening proportional to I)
1, and when the humidity difference (ΔRHH) is within a predetermined humidity difference, and the temperature difference (6 dens) exceeds the predetermined humidity difference, if the room temperature is higher than the set temperature, the temperature difference (ΔT )
A second temperature control that closes the second electronic expansion valve (6) to an opening proportional to the temperature difference (ΔT), and, conversely, opens the second electronic expansion valve (6) to an opening proportional to the temperature difference (ΔT) when the temperature is low. The present invention is characterized by comprising means (2).

Further, the present invention provides the temperature difference (ΔT) between the room temperature and the set temperature.
It is preferable that reheat limiting means α instantaneous is provided for closing the second electronic expansion valve (6) when the temperature difference exceeds a high set temperature difference which is larger than the predetermined temperature difference.

Furthermore, the refrigeration cycle is formed into a reversible refrigeration cycle capable of cooling and heating, and the first temperature control means α and the second temperature control means Q6) are configured to be capable of handling both cooling and heating. In addition, when the air conditioning load is large and the temperature difference (ΔT) exceeds a high set temperature difference that is larger than the predetermined temperature difference, the four-way switching valve (7) is switched to the cooling side or to the cooling side according to the air conditioning load condition. Air conditioning control means α that switches to the heating side
It is preferable to provide a scent.

On the other hand, the humidifier (11) is disposed on the downstream side of the reheater (5) in the air flow direction, and the second electronic expansion valve (6) is fully closed controlled by the reheat amount control means aη. , and when the room humidity is lower than the set humidity, the humidifier α
A preferable configuration is that a humidification control means am for operating υ in humidification is provided.

The present invention also provides an inverter-driven variable capacity compressor in which the compressor (11) is frequency-controlled in accordance with the air conditioning load, and on the other hand, the humidity difference (ΔRH) is within a predetermined humidity difference, and the room humidity is lower and the humidity is increasing, the output frequency of the inverter @ is lowered; conversely, when the humidity is decreasing, the output frequency is increased, and when the room temperature is higher and the humidity is increasing, the output frequency is increased. Increase the frequency, and conversely lower the output frequency when the humidity is decreasing, and further increase the humidity difference (ΔR
When the humidity difference (HH) exceeds the predetermined humidity difference, this humidity difference (Δ
A preferred configuration includes a humidity control means (21) that increases the output frequency of the inverter Q2) when the room humidity is high, and lowers the output frequency when the room humidity is low, in response to RH11). be.

(Function) The present invention detects indoor temperature and humidity, and directly controls the cooling capacity of the indoor heat exchanger (4) and the reheating capacity of the reheater (5). Furthermore, since this control is performed steplessly and continuously by the two electronic expansion valves (3) and f6), it is possible to increase control precision and at the same time perform high response control.

(Embodiment) Fig. 1 is a circuit diagram of an apparatus according to an embodiment of the present invention, which includes a compressor (1), a four-way switching valve (7), an outdoor heat exchanger (2) which serves as a condenser during cooling. ), first electronic expansion valve (3), indoor heat exchanger (4) which serves as an evaporator during cooling, and accumulator (
8) forms a known reversible refrigeration cycle,
Cooling and heating operations according to the invention of claim 3 can be performed by switching the four-way switching valve (7), and normally the cooling operation is exclusively carried out most of the year.

Then, a compressor (1), a four-way switching valve (7), a condenser (2
), an accumulator (8) constitutes an outdoor unit, and a first electronic expansion valve (3) and an evaporator (4) constitute an indoor unit.
A thermistor as a temperature-sensing part of a room temperature detector (9) that detects the temperature of the suction air and sends a room temperature signal is placed at the air inlet, and also detects the humidity of the suction air and detects the room temperature. A humidity sensing element of a humidity detector α0) that transmits a signal is arranged, and a first thermistor Q3 as a temperature sensing part of a superheat detector is arranged in the outlet piping and inlet piping of the evaporator (4).
) and a second thermistor Q4) are attached.

The illustrated device further includes a reheat circuit attached to the refrigeration cycle, and this reheat circuit connects a reheat 2m (5) located downstream of the evaporator (4) in the air flow direction and an inlet. The circuit has a circuit configuration in which the second electronic expansion valve (6), which is connected to the heating device (5), is connected in series, and this reheating circuit is connected to the condenser (5).
2) and the first electronic expansion valve (3) are connected in parallel to the refrigerant circuit which is connected in series.

The first electronic expansion valve (3) and the second electronic expansion valve (6) are electrically driven expansion valves in which a pulse motor output shaft is connected to the valve shaft, and the pulse output with changed polarity is pulsed. When applied to the motor, the valve is controlled to the opening side or the throttle side with an opening degree proportional to the number of pulses, and the first electronic expansion valve (3) is controlled to be activated by the signal transmitted from the superheat degree detector. The valve opening degree is adjusted by a pulse output from a circuit (not shown) and a first temperature control means α, which will be described later.
The second electronic expansion valve (6) has its valve opening adjusted by pulse outputs from the reheat amount control means 0η, the reheat limiting means 0, the second temperature control means Q61, and the air conditioning control means α. It has become so.

On the other hand, the compressor (11) is connected to a motor whose rotation is controlled by an inverter, and in addition to the known control method in which the output frequency of the inverter is controlled according to the air conditioning load, Humidity control means (21) having such a configuration
Frequency control is achieved by the pulse output from.

Further, in the above device, a humidifier OD is disposed in the vicinity of the reheater (5) in the indoor unit and on the leeward side of the reheater (5), and the humidifier αυ according to claim 4 is The humidifying operation is performed by the output from the humidifying control means (2).

The control system of the above air conditioner will be explained below with reference to FIGS. 2 to 4. ◎ First temperature control means aω, room temperature signal from room temperature detector (9) and setting from room temperature setting device The first electronic expansion valve (
3), and the temperature difference (ΔT) obtained by subtracting the set temperature from the room temperature is within the range of ±1°C, that is, -
It is determined whether 1'C≦ΔT≦1°C (step ([1)), and if it is within that range, the opening degree of the first electronic expansion valve (3) is maintained at the current state.

On the other hand, when the temperature difference (ΔT) during cooling is T>1°C, that is, higher than the set temperature, and the difference exceeds 1°C, and when during heating, ΔT<−1'C1, that is, higher than the set temperature. When the temperature difference exceeds 1°C, the first electronic expansion valve (3) is opened and closed according to the absolute value of this temperature difference using a linear capacity control method (step (c)).
). However, when the outlet of the evaporator (4) becomes wet or when the evaporation temperature is low, the capacity control is not performed and the protection control is performed.

To give a specific control example, the temperature difference (ΔT ), the target opening degree diagram of the ascending linear characteristic is obtained, and the target opening degree is calculated at every sampling time (30 seconds), and the following operation is performed.

i) If the target opening is the current opening (closed direction), the first electronic expansion valve (3 ) close.

ii) Target opening degree> In the case of the current opening degree (opening direction), the expansion valve (3) is opened by the number of pulses proportional to the difference between the exit superheat degree of the evaporator (4) and the set superheat degree, for example, 5°C.

Note that if the current opening is within the range of ±10 pulses with respect to the target opening, that opening is maintained.

iii) Low-temperature protection: If the inlet temperature T is below the set temperature, the expansion valve is activated by the number of pulses proportional to the difference between the inlet temperature T and the set temperature, regardless of the magnitude relationship between the target opening and the current opening. Open (3) to increase the evaporation temperature.

■) Moisture protection: If the superheat degree falls below the set superheat degree (5℃), regardless of the magnitude relationship between the target opening degree and the current opening degree, the superheat degree
The expansion valve (3) is closed by the number of pulses proportional to the difference in degrees Celsius to increase the degree of superheat.

◎ A reheat amount control means αη receives a temperature difference signal corresponding to the temperature difference (ΔT), a room temperature signal from the humidity detector α field, and a set humidity signal as input signals, and sends them to the second electronic expansion valve (6). It provides an output, and the temperature difference (ΔT) is within a predetermined temperature difference, that is,
-1℃≦∆T 51T: Is the humidity difference (∆RH11) obtained by subtracting the set humidity from the room humidity within the predetermined humidity difference range, for example, within the range of ±10% (-10≦∆RHH≦10)? is determined (Step (G)), and if it is within that range, the opening degree of the second electronic expansion valve (6) is maintained at the current level (Step (G)).

On the other hand, when the humidity difference (ΔRH11) is outside the above range and the room humidity is higher (ΔRH1+>10%), the operation state requires dehumidification, so the second electronic expansion valve (6) is By opening the number of pulses proportional to (ΔRHH), the amount of refrigerant flowing to the reheater (5) is increased, and the reheating capacity is increased (step (+7)').

On the contrary, room humidity is lower (ΔRH11>10%
), the operating state requires humidification, so the reheating capacity is reduced by closing the second electronic expansion valve (+9) by the number of pulses proportional to the humidity difference (ΔRHH).
Step (su)).

◎ Second temperature control means αe, the humidity difference (ΔRHH) is within a predetermined humidity difference, that is,
−10%≦ΔRHH≦10%, temperature difference (ΔT)
is activated when the temperature difference exceeds a predetermined temperature difference, and the temperature difference signal corresponding to the temperature difference (ΔT) and the humidity difference (ΔRHH
) in response to a humidity difference signal corresponding to the second electronic expansion valve (6).
gives the output.

In other words, room temperature is 1°C higher when air conditioned, 6162°C.
In addition, during heating, when the temperature is low and T<1°C, the second electronic expansion valve (6) due to the humidity difference (ΔRH)
The indoor heat exchanger (
4) Increase the ability (step (wa)').

On the other hand, room temperature is lower during cooling and is much lower ℃≦ΔT〈-1'C
In addition, during heating, if the temperature is 1'c<6162°C at the highest, the expansion valve (6) is opened by the number of pulses proportional to the temperature difference (ΔT) to increase the capacity of the heat exchanger (4). decrease (step (wa)).

◎ Reheat limiting means side, according to the structure of claim 3, wherein the temperature difference (ΔT
) in response to a temperature difference signal corresponding to the second electronic expansion valve (6).
It is configured to give an output to.

The temperature difference (ΔT) exceeds the predetermined temperature difference (-1°C≦ΔT≦1°C) and becomes equal to or higher than the high set temperature difference, for example, when ΔT>
If the temperature is 2°C and ΔT is 2°C during heating, the second electronic expansion valve (6) is forcibly closed (step (ri)).
, the indoor heat exchanger (4) is operated at maximum capacity.

■ Heating and cooling control means (a), which is according to the structure of claim 2, and is configured to give a switching command to the four-way switching valve (7) in response to a temperature difference signal corresponding to the temperature difference (ΔT). .

That is, when the temperature difference (ΔT) exceeds the set temperature difference and the room temperature is higher (ΔT>2°C), the four-way switching valve (7) is set to the cooling side and the room temperature is lower. (ΔT<-2
℃), the device switches to the heating side (step (ne)).

By providing this control means α, automatic switching between cooling and heating can be achieved in the event of sudden load changes.

(2) Humidification control means (21°) This is a configuration according to claim 4, and is configured to receive the humidity signal from the humidity detector Qω and the set humidity signal and give an on/off output to the humidifier aυ.

The room temperature is lower than the set humidity (ΔR11<-10%) on the condition that the second electronic expansion valve (6) is fully closed (step (ri)) by the reheat amount control means aη.
In this case, a humidification operation command is sent to the humidifier αD.

By providing this control means 12, it is possible to maintain a constant temperature state by supplying heat even in a slightly dry state.

◎ Humidity control means (21), which has the configuration according to claim 5, and receives the humidity signal from the humidity detector α0 and the set humidity signal and connects the inverter (b) which is a power supply device for the drive motor of the compressor (1). It is formed so as to give a frequency conversion output to.

As is well known in the case of an inverter-driven compressor (1), its capacity control is based on the temperature difference (ΔT) within the range of 30 to 120 Hz. When the frequency is greater than the reference value, a frequency increase output of 2 to 3 Hz is generated for each sampling, and when the reference value is met, an output that maintains the current frequency state is generated.
When it is smaller than the reference value, on the other hand, a frequency reduction output of 2 to 3 Hz is generated to control the temperature (step (a)).

In addition to such capacity control, the present invention attempts to increase or decrease the capacity of the compressor (1) in response to changes in humidity, and the humidity difference (ΔRHH) is within a predetermined humidity difference, that is, -1
Depending on whether 0%≦∆RHH≦10%, adaptive capacity control is performed, and if the humidity is within the predetermined humidity,
Humidity difference before sampling (ΔRHH1) and temperature difference at current sampling (ΔRH) I! ), and if the difference becomes 5% or more relative to the set humidity, the frequency is changed by one step.A specific example is as follows, and is shown in step (S).

i) If ΔRH,, ΔRHt<O (when the room temperature is lower), lower the output frequency by 1 step in direction), increase it by 1 step in direction).

ii) ΔRHH+, ΔRHI1. If >0 (room temperature is higher), increase the number by one step and decrease it by one step.

in)ΔRH111>0. ΔRH1h<O or ΔRHH
If +<0°ΔRH1(!>O), the current frequency is held because the room temperature fluctuates from higher to lower than the set humidity or vice versa.

On the other hand, if the humidity difference (ΔRHH) exceeds the predetermined humidity difference, the process proceeds to step (T), and the humidity difference (ΔRHH)
) is larger than the reference value, output increases the frequency by 1 step per sampling, when they match, output maintains the current frequency, and when it is smaller, output decreases the frequency to control the capacity. .

Although the above has been explained separately for each means, the mode of control thereof is shown in FIG. 3 along with the cooling operation state and heating operation state, and furthermore, in FIG. 4, the humidity control means (21) shows the cooling operation state when the capacity of the compressor (1) is controlled according to changes in humidity.

As is clear from the flow of each of these operations, when controlling the indoor temperature and humidity to be maintained in the shaded area on the air diagram in Figure 5, when the temperature and humidity are high, air conditioning (cooling), When the temperature and humidity are low, priority is given to heating, that is, the opening degree of the first electronic expansion valve (3) is increased and the opening degree of the second electronic expansion valve (6) is increased.
) is fully closed or minimized, and when the temperature reaches the set range, humidity control is performed by controlling the opening of the second electronic expansion valve (6), and the cooling (heating) priority system is activated. The operation control shown in FIGS. 3 and 4 is implemented.

In this way, it is possible to perform stable operation in which the room temperature and room temperature are kept constant by having a reheating function.

(Effect of the invention) By controlling the valve opening degree of the first electronic expansion valve (3) by the first temperature control means α, the heat exchange capacity of the indoor heat exchanger (4) can be adjusted steplessly in response to the air conditioning load. It can be adjusted to
The capacity of the reheater (5) can be adjusted to increase or decrease according to the room humidity by controlling the opening degree of the second electronic expansion valve (6) by the reheat amount control means an, so that the room temperature and humidity can be kept in a state where the range of fluctuation is small. temperature and humidity control accuracy can be dramatically improved.

Furthermore, if there is a temperature fluctuation while the room humidity is maintained, the capacity of the reheater (5) is controlled to increase or decrease by the second temperature control means αe, so that the temperature can be increased while suppressing the humidity fluctuation. Control can be performed reliably.

In this way, room temperature and room humidity can be kept constant throughout the year.

In addition, in claim 2, a reversible system is adopted in the refrigeration cycle to enable switching between cooling and heating, and when there is a large drop in room temperature during cooling operation or a large rise in room temperature during heating operation, heating and cooling control is performed. By configuring the system to be able to automatically switch to heating or cooling using the means α, the temperature control period can be further expanded and the system can be fully adapted to environments with severe temperature fluctuations.

Furthermore, in claim 3, when the room temperature has a significant temperature difference with respect to the set temperature, the function of the reheater (5) is suppressed by the reheat limiting means α instantaneous, so that the indoor heat The exchanger (4) is operated at maximum capacity for the load to ensure stable temperature maintenance.

Further, in claim 4, a humidifier aD is attached, and the humidifier a0 is operated by the humidification control means C21 when the room humidity cannot be maintained at a constant level at low humidity.
High reliability is maintained without creating an unfavorable environment that is too dry.

Furthermore, in claim 5, the humidity control means (21) performs not only the capacity control on the heat exchanger side but also the capacity control of the compressor in response to fluctuations in room humidity. Control is possible.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a device according to an embodiment of the present invention, Fig. 2 is the same (block diagram of the control system), and Figs. 3 and 4 are flow diagrams showing operation control of an example of the device of the present invention. , Fig. 5 is an air diagram for explaining the mode of temperature and humidity control. (1)...Compressor, (2)...Outdoor heat exchanger (condenser), (3)...・・・
・First electronic expansion valve, (4)... Indoor heat exchanger (evaporator), (5)...
Reheater, (6)...Second electronic expansion valve, (7)...
Four-way switching valve, (9)...Room temperature detector, (II...
Humidity detector, Ql)... Humidifier, (2)... Inverter, QSI... First temperature control means, (II... Second temperature control means, αη... Reheat amount control means, Ql... Reheat limiting means, Ql... Cooling/heating control means, am... Humidification control means, (21)... Humidity control means. Z:j-possessed (0C)

Claims (5)

[Claims] 1. Compressor (1), condenser (2) installed on the outdoor side, first
An electronic expansion valve (3) and an evaporator (4) provided on the indoor side form a refrigeration cycle, and a reheater (5) is arranged on the downstream side of the evaporator (4) in the air flow direction. Reheater (5
) and the second electronic expansion valve (6) are connected in parallel to the refrigerant circuit connected in series with the condenser (2) and the first electronic expansion valve (3). vessel(
4), a room temperature detector (9) that detects the suction air temperature, and a humidity detector (10) that detects the suction air humidity of the evaporator (4).
), and if the room temperature detected by the room temperature detector (9) is higher than the set temperature and exceeds a predetermined temperature difference, the first electronic expansion valve (3) is activated in proportion to the temperature difference (ΔT) at that time. the first temperature control means a, which controls the opening degree to the temperature difference (ΔT
) is within a predetermined temperature difference, if the room humidity measured by the humidity detector (10) exceeds the predetermined humidity difference with respect to the set humidity, if the room humidity is higher, the second electronic expansion valve (6 ) to an opening proportional to the humidity difference (ΔRH) at that time,
Conversely, when the humidity is low, the second electronic expansion valve (6) is closed to an opening proportional to the humidity difference (ΔRH) at that time; When the temperature difference (ΔT) exceeds the predetermined humidity difference, if the room temperature is higher than the set temperature, the temperature difference (ΔT) exceeds the predetermined humidity difference.
The second electronic expansion valve (6) is closed to an opening proportional to the temperature difference (ΔT), and conversely, when the temperature difference is low, the second electronic expansion valve (6) is opened to an opening proportional to the temperature difference (ΔT). Temperature control means (1
6) An air conditioner characterized by comprising: 2. Compressor (1), four-way switching valve (7), outdoor heat exchanger (2) that serves as a condenser for cooling provided on the outdoor side, first electronic expansion valve (3), provided on the indoor side for cooling A reversible refrigeration cycle is formed by an indoor heat exchanger (4) serving as an evaporator, and a reheater (5) is disposed on the downstream side in the air flow direction with respect to the indoor heat exchanger (4). A refrigerant circuit in which a reheater (5) and a second electronic expansion valve (6) are connected in series is a refrigerant circuit in which an outdoor heat exchanger (2) and a first electronic expansion valve (3) are connected in series. while the indoor heat exchanger (4)
The room temperature detected by the room temperature detector (9) which detects the temperature of the intake air, the humidity detector (10) which also detects the humidity of the intake air, and the room temperature detector (9) is higher than the set temperature during cooling.
During heating, if the temperature is low and exceeds a predetermined temperature difference, the first temperature control means (15) controls the first electronic expansion valve (3) to an opening proportional to the temperature difference (ΔT) at that time. )and,
When the temperature difference (ΔT) is within a predetermined temperature difference, if the room humidity measured by the humidity detector (10) exceeds the predetermined humidity difference with respect to the set humidity, if the room humidity is higher, the second The electronic expansion valve (6) is opened to an opening proportional to the humidity difference (ΔRH) at that time, and when the humidity is low, the second electronic expansion valve (6) is opened.
reheating amount control means (17) for closing the opening to an opening proportional to the humidity difference (ΔRH) at that time, and the humidity difference (ΔRH)
is within a predetermined humidity difference, and if the temperature difference (ΔT) exceeds the predetermined temperature difference, if the room temperature is higher than the set temperature, a second electron is applied to the opening proportional to the temperature difference (ΔT). The expansion valve (6) is closed during cooling and opened during heating; conversely, when the temperature is low, the second electronic expansion valve (6) is opened to an opening proportional to the temperature difference (ΔT) during cooling, and opened during heating. a second temperature control means (16) that closes the four-way switching valve (7) when the temperature difference (ΔT) exceeds a high set temperature difference that is larger than the predetermined temperature difference; This air conditioner is characterized by being provided with an air conditioning control hand (19) that switches to the cooling side when the temperature is high and to the heating side when the temperature is low. 3. reheat limiting means (18) for closing the second electronic expansion valve (6) when the temperature difference (ΔT) between the room temperature and the set temperature exceeds a high set temperature difference that is larger than the predetermined temperature difference;
The air conditioner according to claim 1 or 2, further comprising: an air conditioner. 4. The humidifier (11) is disposed on the downstream side of the reheater (5) in the air flow direction, while the reheat amount control means (17)
a humidification control means (20) for operating the humidifier (11) when the second electronic expansion valve (6) is fully closed and the room humidity is lower than the set humidity; The air conditioner according to any one of claims 1 to 3. 5. The compressor (1) is an inverter-driven variable capacity compressor whose frequency is controlled according to the air conditioning load;
When the humidity difference (ΔRH) is within a predetermined humidity difference, the room humidity is lower, and the humidity is increasing, the inverter (
12) Decrease the output frequency, and conversely increase the output frequency when the humidity is decreasing, and increase the output frequency when the room humidity is higher and the humidity is increasing, and conversely when the humidity is decreasing. Lower the output frequency and further reduce the humidity difference (ΔRH)
exceeds the specified humidity difference, this humidity difference (ΔRH)
When the room humidity is higher, the inverter (12)
Claims 1 to 4 further comprising a humidity control means (21) for increasing the output frequency of the humidity control device and lowering the output frequency when the output frequency is low.
The air conditioner according to any of the above.