JP3514919B2 - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to fitly effect, in dehumidification in an indoor heat exchanger, the setting of regions as regards the evaporating region and superheating region jointly with the control of superheating so as to make the dehumidification take place properly and in a stabilized state without involving a lowering of the indoor temperature. SOLUTION: An indoor heat exchanger (auxiliary indoor heat exchanger 7 + main indoor heat exchanger 8) is equipped with heat-exchanger temperature sensors 13, 14 provided at a target evaporation region (auxiliary indoor heat exchanger 7) and a target superheating region (main indoor heat exchanger 8) respectively in a setup to control, in the dehumidification cycle, the opening of a motor-operated expansion valve 24, on the basis of the difference between the detected temperatures of the two temperature sensors, in a manner of controlling the superheating. On the other hand, it is checked whether the motor- operated expansion valve 26 has been throttled to excess or not from the detected temperature Tcj of the heat-exchanger temperature sensor 13 following the throttling of the motor-operated expansion valve 24 in the control of the superheating. If actually an excess in throttling has been detected, the opening of the motor-operated expansion valve 26 is corrected toward a decrease.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls the opening of an electric expansion valve to set an evaporation area and a superheat area in an indoor heat exchanger,
The present invention relates to an air conditioner that performs dehumidification.

[0002]

2. Description of the Related Art Air conditioners include compressors, outdoor heat exchangers,
It is possible to cool the room by providing a refrigeration cycle in which an expansion mechanism and an indoor heat exchanger are sequentially connected to circulate a refrigerant, and the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator. In addition, since water in the air is condensed in the indoor heat exchanger with cooling, it is possible to dehumidify the room.

However, during the period when the room temperature is not so high and the humidity is high, dehumidification itself is desired rather than cooling. There is the following example as an air conditioner that independently has a dehumidifying operation function in addition to the cooling operation.

(1) By turning on / off the operation of the weak cooling, a dehumidifying action can be obtained without significantly lowering the indoor temperature. (2) Cooling and dehumidifying indoor air by cooling operation,
The temperature drop due to cooling is offset by the heat generated by the electric heater.

(3) The indoor heat exchanger is divided into two and an expansion valve is interposed between the two heat exchangers, so that one heat exchanger is an evaporator and the other heat exchanger is an outdoor heat exchanger. Similarly, it also functions as a condenser (reheater), warms the air cooled and dehumidified on the evaporator side and blows it out into the room.

However, in the dehumidifying operation of (1), the evaporation temperature of the refrigerant in the indoor heat exchanger becomes high because of the weak cooling, and the difference between the evaporation temperature and the dew point temperature of the intake air becomes small, so that sufficient dehumidification is performed. I can't get the ability.

In the dehumidifying operation of (2), since it is necessary to generate heat from the heater corresponding to the cooling capacity, it is necessary to prepare a large-sized electric heater, and there is a problem that power consumption increases.

In the dehumidifying operation of (3), since the indoor unit has an expansion valve, a sudden expansion noise of the refrigerant leaks into the room and the residents feel uncomfortable. In addition, the unbalanced cycle of the condenser (outdoor heat exchanger + reheater) is large and the evaporator is small, so the refrigerant liquefied in the condenser is sucked into the compressor without being completely evaporated in the evaporator. There is a concern that liquid back will occur and that the compressor will overheat due to the accumulation of refrigerant in the condenser.

Therefore, recently, the indoor heat exchanger is thermally separated into an auxiliary heat exchanger section and a main heat exchanger section without providing a throttle in the middle, and the auxiliary heat exchanger section and the main heat exchanger section are separated. The opening of the electric expansion valve is controlled so as to keep the temperature difference constant, so that the auxiliary heat exchanger part functions as the evaporation region and the main heat exchanger part functions as the overheat region, and the dehumidifying action is performed only in the auxiliary heat exchanger part. An air conditioner that can be used in a vehicle has been developed and is being put to practical use. According to this air conditioner, without causing an increase in power consumption,
It is possible to dehumidify the room without lowering the room temperature without leaking an unpleasant noise into the room and without causing the liquid bag or the abnormal overheating of the compressor.

[0010]

In the refrigerating cycle, the temperature of the indoor heat exchanger and the suction refrigerant temperature (suction temperature) of the compressor are detected by temperature sensors, respectively, and the superheat (superheat) corresponding to the difference between the two detected temperatures is detected. ) Generally, the opening degree of the electric expansion valve is adjusted so that the amount becomes equal to a target superheat amount that is determined by the operating frequency of the compressor, the outside air temperature, and the like. Due to this superheat control, stable cooling capacity, dehumidifying capacity,
Or I try to get the heating capacity.

However, depending on the operating conditions, the superheat region, that is, the overheat region, may spread to the temperature sensor position of the indoor heat exchanger. If this happens, the difference between the detected temperatures of both temperature sensors becomes small and the apparent amount of superheat decreases. Therefore, the opening of the electric expansion valve is narrowed down to compensate for this. This is a so-called over-throttled state. In such a case, stable cooling capacity, dehumidifying capacity, or heating capacity cannot be exerted.

In the case of the air conditioner for dehumidifying by setting the evaporation area and the overheating area in the indoor heat exchanger as described above, the temperatures of the evaporation area and the overheating area are respectively detected and the difference between the detected temperatures is calculated as the superheat amount. The opening degree of the electric expansion valve is controlled so that the amount of superheat becomes constant, but depending on the operating conditions, the overheat area expands to the temperature detection position in the evaporation area, and the difference between the two detection temperatures decreases or becomes zero. Sometimes (decreased apparent superheat).

In this case, the opening of the electric expansion valve is narrowed to compensate for the decrease in the superheat amount. However, the temperature detection position in the overheating region is sufficiently overheated and is almost the same temperature as the intake air temperature from the room, and even if the opening of the electric expansion valve is throttled, the temperature does not change any further. . That is, since the superheat region is still expanded to the place where it should be the evaporation region and the opening degree of the electric expansion valve is narrowed in addition, the dehumidifying action cannot be obtained.

The present invention takes the above circumstances into consideration,
The air conditioners of the first and second aspects of the present invention can appropriately set the regions of the evaporation region and the superheat region in the indoor heat exchanger during dehumidification together with the superheat control, thereby preventing the indoor temperature from decreasing. A stable dehumidifying action can be reliably obtained , and the rise of the dehumidifying action and the indoor temperature can be improved.
The purpose is to improve the stability of the degree .

[0015]

[0016]

[0017]

[0018]

[0019]

The air conditioner of the first invention is a refrigeration cycle in which a compressor, an outdoor heat exchanger, an electric expansion valve, and an indoor heat exchanger are sequentially communicated with each other, and an indoor heat exchange during a dehumidification cycle. Evaporation area temperature sensor and superheat area temperature sensor provided in the target evaporation area
The opening degree of the electric expansion valve is superheat-controlled based on the difference between the temperature detected by the temperature sensor and the temperature detected by the overheat zone temperature sensor, and after the electric expansion valve is throttled by the superheat control. sensing the temperature change in the evaporator region temperature sensor
If the detected temperature change increases, the electric expansion
A first over-throttle detection means for judging that the valve is over-throttled, and when the first over-throttle detection means detects an over-throttled state,
It provided first over aperture protection hand stage to open the electric expansion valve by a predetermined opening degree.

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

The air conditioner of the second invention comprises a compressor, an indoor heat exchanger, an electric expansion valve, a refrigerating cycle in which the indoor heat exchanger is in communication, an indoor temperature sensor for detecting the indoor temperature, Equipped with an evaporation zone temperature sensor and an overheat zone temperature sensor provided in the target evaporation zone and the target overheat zone in the indoor heat exchanger during the dehumidification cycle, the difference between the temperature detected by the evaporation zone temperature sensor and the temperature detected by the overheat zone temperature sensor The superheat control of the opening degree of the electric expansion valve based on, detects the difference between the detection temperature of the evaporation zone temperature sensor and the detection temperature of the indoor temperature sensor after a predetermined time from the start of operation , this difference is When the electric expansion valve has a predetermined value or less, it is determined that the electric expansion valve is over-throttled, and a second over-throttlement detection means is provided. the predetermined opening degree of the electric expansion valve It provided second over aperture protection hand stage to open only.

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

DETAILED DESCRIPTION OF THE INVENTION

(A) A first embodiment of the present invention will be described below with reference to the drawings. In FIG. 3, reference numeral 1 denotes an indoor unit, which has an indoor air suction port 2 on the front surface, an indoor air suction port 3 on the upper surface, and air conditioning air (cooling air, dehumidified air, heating) on the lower front surface. Air outlet 4).

In the indoor unit 1, the suction ports 2 and 3 are provided.
From this to the air outlet 4, the ventilation path 5 is formed. In this ventilation path 5, a dustproof (and deodorant) filter 6 is provided inside the suction ports 2 and 3, and a main indoor heat exchanger 8 and an auxiliary indoor heat exchanger 7 are arranged inside the filter 6. Set up. Then, a cross-flow type indoor fan 9 is arranged inside both heat exchangers 7, 8.

The main indoor heat exchanger 8 is divided into a first heat exchanger 8a and a second heat exchanger 8b.
b is arranged in an inverted V shape so as to surround the indoor fan 9.
The first heat exchanger 8a faces the suction port 2 on the front surface, and the second heat exchanger 8b faces the suction port 3 on the upper surface. The auxiliary indoor heat exchanger 7 is arranged between the second heat exchanger 8b and the suction port 3, that is, at a position on the windward side above the second heat exchanger 8b in the indoor air intake passage. .

The drain receiving portion 1 is provided below the first heat exchanger 8a.
9a is formed. A drain receiving portion 19b is formed below the second heat exchanger 8b and the auxiliary indoor heat exchanger 7. The radiating fins of the first heat exchanger 8a and the radiating fins of the second heat exchanger 8b are in contact with each other, but between the radiating fins of the second heat exchanger 8b and the radiating fins of the auxiliary indoor heat exchanger 7. A gap is secured between the two radiating fins so that they are not in contact with each other, that is, they are thermally separated.

When the indoor fan 9 rotates, indoor air passes through the suction port 2 and the suction port 3, respectively, and the indoor unit 1
Is sucked in. The suction air from the suction port 2 flows through the filter 6, the first heat exchanger 8a, and the indoor fan 9 side. After passing through the filter 6, the suction air from the suction port 3 first flows through the auxiliary indoor heat exchanger 7 and then through the second heat exchanger 8b toward the indoor fan 9 side.

A left-right louver 10 is provided in the ventilation passage 5 at a position facing the outlet 4 on the downstream side of the indoor fan 9. The left-right louver 10 is for manually setting the direction of the blowing air in the left-right direction of the indoor unit 1.

A plurality of, for example, a pair of vertical louvers 11, 11 are vertically arranged side by side on the downstream side of the horizontal louver 10. The vertical louvers 11 and 11 are driven by a single motor in conjunction with each other, and during operation, rotate in the counterclockwise direction in the figure to open the air outlet 4 and change the direction of the blowing air to the vertical direction of the indoor unit 1. The direction is set in the direction, and when the operation is stopped, it rotates clockwise in the drawing to close the air outlet 4, thereby preventing dust from entering the indoor unit 1.

On the other hand, as shown in FIG. 1, an outdoor heat exchanger 23 is connected to the discharge port of the compressor 21 via a four-way valve 22, and an expansion mechanism such as an electric expansion valve 24 is connected to the outdoor heat exchanger 23. Connected by piping. The opening degree of the electric expansion valve 24 continuously changes according to the number of input drive pulses.

One end of the auxiliary indoor heat exchanger 7 is connected to the electric expansion valve 24 by piping, and the other end of the auxiliary indoor heat exchanger 7 is connected to the main indoor heat exchanger 8 (the first heat exchanger 8a and the second heat exchanger). The device 8b) is piped. And the main indoor heat exchanger 8
The suction port of the compressor 1 is connected to the pipe via the four-way valve 2.

In this way, a heat pump type refrigeration cycle capable of cooling, dehumidifying and heating is constructed. During cooling, the refrigerant discharged from the compressor 1 flows from the four-way valve 22 to the outdoor heat exchanger 23, the electric expansion valve 24, the auxiliary indoor heat exchanger 7, and the main indoor heat exchanger 8 during cooling. A cooling cycle is formed in which the refrigerant that has flowed through the main indoor heat exchanger 8 returns to the compressor 1 through the four-way valve 22. That is, the outdoor heat exchanger 23 functions as a condenser, and the auxiliary indoor heat exchanger 7 and the main indoor heat exchanger 8 function as an evaporator.

During dehumidification, a dehumidification cycle in which the refrigerant flows in the same direction as during cooling is formed. During heating, the four-way valve 22 is switched so that the refrigerant discharged from the compressor 1 flows from the four-way valve 22 to the main indoor heat exchanger 8, the auxiliary indoor heat exchanger 7, and the electric expansion as shown by the broken line arrow in the figure. A cycle is formed in which the refrigerant sequentially flows to the valve 24 and the outdoor heat exchanger 23, and the refrigerant passing through the outdoor heat exchanger 23 returns to the compressor 1 through the four-way valve 22. That is, the auxiliary indoor heat exchanger 7 and the main indoor heat exchanger 8 function as a condenser, and the outdoor heat exchanger 23 functions as an evaporator.

The specific construction of the electric expansion valve 24 is shown in FIG. That is, the electric expansion valve 24 is connected to the refrigerant pipe 5
It has a housing 50 connected between the first and the second parts. This case 5
The rod 53 is rotatably held in the shaft 0 through the support member 54. The valve rod accommodating space 53 is provided at one end of the rod 53.
A is formed, and the valve rod 54 is vertically movably accommodated in the valve rod accommodation space 53a. The valve rod 54 has its tip facing the opening of the pipe 51, and closes the valve seat 51a around the opening by closing it.

A spring 55 is housed in the housing space 53a, and the spring 55 applies a biasing force to the valve rod 54 in the closing direction. The interposition of the spring 55 absorbs the pressing force when the valve rod 54 contacts the valve seat 51a, and prevents the valve rod 54 from biting into the valve seat 51a.

The rotor winding 56 is wound around the other end of the rod 53, and the stator winding 57 is wound around the outer peripheral surface of the housing 50. The magnetic field generated by the excitation of the stator winding 57 acts on the rotor winding 56, whereby the rod 53 rotates and the valve rod 54 moves up and down.

Auxiliary indoor heat exchanger 7 and heat exchanger 8a,
Of 8b, the heat exchanger temperature sensor 13 that functions as an evaporation zone temperature sensor is attached to the heat exchange pipe of the auxiliary indoor heat exchanger 7 that serves as the target evaporation zone during the dehumidification cycle. Furthermore, the heat exchanger 8 which becomes the target overheat region during the dehumidification cycle
A heat exchanger temperature sensor 14 that functions as an overheat region temperature sensor is attached to the heat exchange pipe in the middle portion of the first heat exchanger 8a among a and 8b.

An indoor temperature sensor 15 is provided in the indoor air intake passage from the intake port 2 to the main indoor heat exchanger 8. A suction refrigerant temperature sensor 16 is attached to a pipe between the four-way valve 22 and the suction port of the compressor 21. The heat exchanger temperature sensor 17 is attached to the outdoor heat exchanger 23. An outdoor fan 25 is provided near the outdoor heat exchanger 23. The outdoor fan 25 supplies outdoor air to the outdoor heat exchanger 23. An outdoor air temperature sensor 18 that detects the outdoor air temperature is provided near the outdoor fan 25.

The commercial AC power supply 30 is connected to the inverter circuit 3
1, the speed control circuits 32 and 33, and the control unit 40 are connected. Then, in the control unit 40, the inverter circuit 31,
Speed control circuits 32 and 33, vertical louver motor 11
M, heat exchanger temperature sensors 13 and 14, indoor temperature sensor 1
5, heat exchanger temperature sensor 16, heat exchanger temperature sensor 1
7, outside air temperature sensor 18, four-way valve 22, electric expansion valve 2
4 and the light receiving unit 41 are connected.

The inverter circuit 31 rectifies the power supply voltage, converts it into an alternating current of a frequency F (and voltage) according to a command from the control unit 40, and outputs it. This output serves as drive power for the drive motor (compressor motor) of the compressor 21.

The speed control circuit 32 is used for the outdoor fan motor 2
By controlling the supply of the power supply voltage to 5M (for example, energization phase control), the speed of the outdoor fan motor 25M (the amount of air blown by the outdoor fan 25) is set to the speed according to the command from the control unit 40. The speed control circuit 33 sets the speed of the indoor fan motor 9M (amount of air blown by the indoor fan 9) to a speed according to a command from the control unit 40 by controlling the supply of the power supply voltage to the indoor fan motor 9M (for example, energization phase control). To do.

The light receiving section 41 receives infrared light emitted from a remote control type operation device (hereinafter abbreviated as a remote controller) 42. The control unit 40 performs overall control of the air conditioner, and includes the following [1] to [21] as main functional means.

[1] When the cooling operation mode is set by the remote controller 42, the cooling cycle is formed to form the outdoor heat exchanger 23.
The condenser, the auxiliary indoor heat exchanger 7 and the main indoor heat exchanger 8
And control means that both function as an evaporator.

[2] Control means for controlling the operating frequency (output frequency of the inverter circuit 31) F of the compressor 21 in accordance with the temperature Ta detected by the indoor temperature sensor 15 during the cooling operation. [3] During cooling operation, the difference between the suction refrigerant temperature Tsuc detected by the suction refrigerant temperature sensor 16 and the temperature Tc of the main indoor heat exchanger 8 detected by the heat exchanger temperature sensor 14 is captured as a superheat amount, Cooling superheat control means for controlling the opening degree of the electric expansion valve 24 so that the superheat amount becomes a constant value.

[4] When the heating operation mode is set by the remote controller 42, the four-way valve 22 is switched to form a heating cycle, and the auxiliary indoor heat exchanger 7 and the main indoor heat exchanger 8 are both condenser and outdoor heat. Control means for causing the exchanger 23 to function as an evaporator.

[5] Control means for controlling the operating frequency F of the compressor 21 according to the temperature Ta detected by the indoor temperature sensor 15 during the heating operation. [6] During heating operation, the difference between the suction refrigerant temperature Tsuc detected by the suction refrigerant temperature sensor 16 and the temperature Te of the outdoor heat exchanger 23 detected by the heat exchanger temperature sensor 17 is detected as the superheat amount, and the superheat amount is obtained. Heating / superheat control means for controlling the opening of the electric expansion valve 24 so that the amount becomes a constant value.

[8] When the dehumidifying operation mode is set by the remote controller 42, a dehumidifying cycle is formed and the outdoor heat exchanger 23 is formed.
Is a condenser, and a control means for causing the auxiliary indoor heat exchanger 7 to function as an evaporator.

[9] Control means for controlling the operating frequency F of the compressor 21 in accordance with the temperature Ta detected by the indoor temperature sensor 15 during dehumidifying operation. [10] During the dehumidifying operation, the temperature Tc of the main indoor heat exchanger 8 detected by the heat exchanger temperature sensor 14 and the heat exchanger temperature sensor 1
The difference (= Tc-Tcj) from the temperature Tcj of the auxiliary indoor heat exchanger 7 detected in 3 is captured as the superheat amount SHa, and the superheat amount SHa is the target superheat amount S
Dehumidifying superheat control means for controlling the opening degree of the electric expansion valve 24 so that Ho becomes constant.

The target superheat amount SHo is used for stabilizing the refrigeration cycle, setting the auxiliary indoor heat exchanger 7 in the refrigerant evaporation region, and setting the main indoor heat exchanger 8 in the refrigerant overheating region. It also serves as a value and is sequentially set according to the operating frequency F of the compressor 21.

[11] During the superheat control during the dehumidifying operation, the opening degree of the electric expansion valve 24 is changed every predetermined time, and the time interval for changing the valve opening degree is set to a transitional period until the refrigeration cycle stabilizes. Means to make it different from the later stable period.

[12] Means for determining whether the refrigeration cycle is in the transition period or in the stable period based on the temperatures Tcj and Tc detected by the heat exchanger temperature sensors 13 and 14. [13] Means for varying the amount of change in the opening degree of the electric expansion valve 24 during the dehumidifying operation during the transition period and the stable period, which are determined as described above.

[14] During the dehumidifying operation, the heat exchanger temperature sensor 1 after the electric expansion valve 24 is throttled by the superheat control
A first over-throttle detection means for detecting an over-throttle of the electric expansion valve 24 according to a difference between the detected temperature (overheat zone temperature) Tc of 4 and the detected temperature (evaporation zone temperature) Tcj of the heat exchanger temperature sensor 13.

In the actual over-throttled state, the temperature Tc detected by the heat exchanger temperature sensor 14 does not change (because it is sufficiently overheated), and the temperature Tcj detected by the heat exchanger temperature sensor 13 changes. Therefore, the detection temperature Tcj of the heat exchanger temperature sensor 13 is the main detection element. Specifically, when the detected temperature Tcj of the heat exchanger temperature sensor 13 is increased, it is determined that the throttle valve is in the over-throttled state, and when it is not increased, the non-over-throttled state is determined. The same is true if the difference between the detected temperatures Tc and Tcj is increased and the over-throttled state is determined. If the difference is not increased, the non-over-throttled state is determined. Also, the detected temperature Tcj
Is increased and the change in the detected temperature Tc is less than or equal to a predetermined value, it is determined to be the over-throttled state.

[15] During dehumidifying operation, overthrottle of the electric expansion valve is detected according to the difference between the temperature Tcj detected by the heat exchanger temperature sensor 13 and the temperature Ta detected by the indoor temperature sensor 15 after a predetermined time has elapsed from the start of operation. Second over-aperture detecting means. In particular,
When the difference between the detected temperature Ta and the detected temperature Tcj is less than or equal to a predetermined value, it is determined that the over-throttled state.

[16] First over-throttle protection means for opening the electric expansion valve 24 by a first opening amount (for example, 5 pulses) when an over-throttled state is detected by the first over-throttlement detection means. [17] Second over-throttle protection means for opening the electric expansion valve 24 by a second opening amount (for example, 15 pulses) when the second over-throttle detection means detects the over-throttle state.

[18] When the heating operation mode is set by the remote controller 42, a heating cycle is formed to form the auxiliary indoor heat exchanger 7 and the main indoor heat exchanger 8 together as an evaporator, and the outdoor heat exchanger 23 as a condenser. Control means to function as.

[19] Control means for controlling the operating frequency F of the compressor 21 according to the temperature Ta detected by the indoor temperature sensor 15 during the heating operation. [20] During heating operation, heating that detects an over-throttle of the electric expansion valve 24 according to a difference between a temperature Tc detected by the heat exchanger temperature sensor 14 and a temperature Ta detected by the indoor temperature sensor 15 after a lapse of a predetermined time from the start of operation. Over-throttle detection means. Specifically, the detected temperature T
If the difference between a and the detected temperature Tc is less than or equal to a predetermined value, it is determined that the state is an over-throttled state. The predetermined value is set to a large value when the operating frequency F of the compressor 21 is high and a small value when the operating frequency F is low.

[21] Heating over-throttle protection means for opening the opening of the electric expansion valve 24 by a predetermined opening (for example, 30 pulses) every predetermined time when an over-throttled state is detected by the heating over-throttle detection means.

Next, the operation of the above configuration will be described. (1) Dehumidification operation mode When the dehumidification operation mode is set by the remote controller 42 and the operation start operation is performed, the compressor 21 is activated to form the dehumidification cycle, and the operation of the indoor fan 9 and the outdoor fan 25 is performed. The dehumidification operation is started. The operation during the dehumidifying operation is shown in the flowchart of FIG.

First, the opening of the electric expansion valve 24 is set to the initial opening for dehumidifying operation (step 101). This initial opening is a value smaller than the initial opening when the cooling operation is started.

For example, if the initial opening "200" is set at the start of the cooling operation, the initial opening "150" is set at the start of the dehumidifying operation. Numbers "200" and "1
50 ″ is the number of drive pulses supplied to the electric expansion valve 24. The larger the value, the larger the opening degree of the electric expansion valve 24.

By setting the initial opening "150", the temperature Tcj of the auxiliary indoor heat exchanger 7 can be swiftly lowered to a temperature equal to or lower than the dew point temperature which is a value suitable for dehumidification. This accelerates the rise of the dehumidifying action.

Temperature T of air sucked into indoor unit 1
a is detected by the indoor temperature sensor 15, and the detected temperature Ta
The difference .DELTA.T (= Ta-Ts) between the temperature and the set temperature Ts is obtained (step 102). Then, the operating frequency F of the compressor 21 is controlled according to the temperature difference ΔT (step 103).
That is, as the temperature difference ΔT is larger, the operating frequency F is set higher and the capacity of the compressor 21 is increased.

As the actual value of the operating frequency F during the dehumidifying operation is selected to be much lower than that during the cooling operation, the power consumption can be reduced and the energy saving effect can be obtained. When a certain time has passed from the start of operation (step 104
YES), the target superheat amount SHo corresponding to the operating frequency F of the compressor 21 is determined (step 105).

The difference (= Tc) between the temperature Tc of the main indoor heat exchanger 8 detected by the heat exchanger temperature sensor 14 and the temperature Tcj of the auxiliary indoor heat exchanger 7 detected by the heat exchanger temperature sensor 13.
-Tcj) is captured as the superheat amount SHa (step 106), and the opening correction timing is determined according to the superheat amount SHa (step 107). For example, if the superheat amount SHa is less than the set value 5 ° C,
After determining that the refrigeration cycle is in a transitional state, 1 minute is determined as the opening correction timing. If the superheat amount SHa is larger than the set value 5 ° C, 3 minutes is determined as the opening correction timing based on the judgment that the refrigeration cycle is in the stable state.

At the opening correction timing (step 10
8 YES), the difference SHd (= SHo-SHa) between the target superheat amount SHo and the actual superheat amount SHa is obtained (step 109). Furthermore, SHd and the previous S
The difference ΔSH with Hd (= SHd-previous SHd) is calculated (step 110). Then, the opening correction amount ΔPLS with respect to the current opening of the electric expansion valve 24 is obtained by a function using the current SHd and the difference ΔSH (step 111).

As the first determination condition (first over-aperture detection), the previous opening correction was in the aperture (reduction) direction (flag flag is "1"), and the above ΔSH (= SHd-
It is confirmed whether or not both the previous SHd) is smaller than zero (ΔSH <0) (step 112).
If satisfied, it is determined that the electric expansion valve 24 is in the over-throttled state, and the opening correction amount ΔPLS thus obtained is increased by 5 pulses which is the first opening amount (step
114).

As the second determination condition (second over-throttle detection), the difference (= Ta-Tcj) between the temperature Ta detected by the indoor temperature sensor 15 and the temperature Tcj detected by the heat exchanger temperature sensor 13 is equal to or less than a predetermined value. It is checked if something is satisfied (step 113). If satisfied, it is determined that the electric expansion valve 24 is in the over-throttled state, and the opening correction amount ΔPLS obtained above is increased by 15 pulses which is the second opening amount (step 115). .

Further, it is judged whether or not the determined opening correction timing is one minute for the transition period (step
116). If it is for the transition period, the opening correction amount ΔPLS is tripled (step 117).

Then, the opening of the electric expansion valve 24 is actually corrected by the opening correction amount ΔPLS (step 118). It is determined whether the opening correction is in the direction of narrowing (reducing) or in the direction of loosening (increasing) (step 119).
). The flag flag is set to "1" in the aperture (reduction) direction (step 120), and the flag flag is set to "0" in the loosening (increase) direction (step 121).

In this way, the difference between the temperature Tc detected by the heat exchanger temperature sensor 14 and the temperature Tcj detected by the heat exchanger temperature sensor 13 is captured as the superheat amount SHa, and the superheat amount SHa is the operating frequency F of the compressor 21. Of the electric expansion valve 24 so as to match the target superheat amount SHo according to
By correcting the opening of the auxiliary indoor heat exchanger 7, the temperature Tcj of the auxiliary indoor heat exchanger 7 becomes equal to or lower than the dew point temperature of the intake air, the auxiliary indoor heat exchanger 7 becomes an evaporation region, and the temperature Tc of the main indoor heat exchanger 8 is increased.
Becomes higher than the dew point temperature of the intake air, and the main indoor heat exchanger 8 becomes an overheat region.

Therefore, the intake air is cooled and dehumidified only in the auxiliary indoor heat exchanger 7, and is blown out into the room without heat exchange in the main indoor heat exchanger 8. The moisture adhering to the auxiliary indoor heat exchanger 7 travels through the heat exchange pipe and the radiation fins of the heat exchanger 7 and drops into the drain receiving portion 19b.

Here, the dehumidifying action of the auxiliary indoor heat exchanger 7 will be described. When the operating frequency F rises, the circulation amount of the refrigerant increases. If the target superheat amount SHo is constant for any operating frequency F,
As the refrigerant circulation amount increases, the auxiliary indoor heat exchanger 7
Only by this, the evaporation of the refrigerant does not end, and the evaporation of the refrigerant also occurs in the main indoor heat exchanger 8. When this happens, not only the function of dehumidification but also cooling (that is, lowering the temperature of indoor air)
The function of is also demonstrated.

If the target superheat amount SHo can be changed according to the change of the operating frequency F, even if the refrigerant circulation amount increases, the evaporation of the refrigerant can be finished only by the auxiliary indoor heat exchanger 7. Therefore, the target superheat amount SHo is set to a value proportional to the operating frequency F. As a result, regardless of changes in compression function,
The dehumidifying action can be given only to the auxiliary indoor heat exchanger 7 to reliably suppress the decrease in the indoor temperature.

In particular, a conventional electric heater for reheating is not required, so that power consumption does not increase. Unlike the conventional case, since the expansion valve (to divide the indoor heat exchanger into the evaporator and the reheater) is not provided in the indoor unit, there is no problem that the rapid expansion noise of the refrigerant leaks into the room. In addition, in the type in which the expansion valve is installed in the indoor unit, the unbalanced cycle in which the condenser (outdoor heat exchanger + reheater) is large and the evaporator is small, and the refrigerant liquefied in the condenser is used in the evaporator. There was a concern that a liquid bag may be sucked into the compressor without being completely evaporated, or that the refrigerant may be accumulated in the condenser and the compressor may be overheated.

Furthermore, since a gap is secured between the heat radiation fins of the auxiliary indoor heat exchanger 7 and the heat radiation fins of the main indoor heat exchanger 8, both the heat radiation fins are in non-contact, that is, they are thermally separated. The heat transfer between the auxiliary indoor heat exchanger 7 and the main indoor heat exchanger 8 is prevented as much as possible, and a sufficient temperature difference can be secured between the dehumidifying area and the overheating area, and the evaporation temperature of the refrigerant can be increased. Can be made sufficiently low, and a high dehumidifying capacity can be secured.

With respect to the construction of the indoor unit 1, there is a suction port 2 on the front surface and a suction port 3 on the upper surface. These suction ports 2 and 3 are connected to the first heat exchanger 8a of the main indoor heat exchanger 8 and the first heat exchanger 8a. Two
The heat exchangers 8a and 8b are opposed to each other, and both heat exchangers 8a and 8b are arranged in an inverted V shape so as to surround the indoor fan 9, and further between the second heat exchanger 8b and the suction port 3 on the upper surface. Since the auxiliary indoor heat exchanger 7 is arranged in the above, it is possible to secure a good ventilation path for the auxiliary indoor heat exchanger 7 and the main indoor heat exchanger 8 while avoiding upsizing of the indoor unit 1. As a result, the heat exchange efficiency between the refrigerant and the sucked air is improved, and the energy saving effect is obtained.

By the way, depending on the operating conditions, the overheat region may extend up to the mounting position of the heat exchanger temperature sensor 13 in the auxiliary indoor heat exchanger 7, and if that happens, the detected temperatures Tcj, Tc of both heat exchanger temperature sensors 13, 14 will be detected. May decrease and the superheat amount SHa may decrease. In this case, the opening degree of the electric expansion valve 24 is narrowed to compensate for the decrease in the superheat amount SHa.
However, the temperature detection position in the original overheating region (the mounting position of the heat exchanger temperature sensor 14) is sufficiently overheated and is almost the same temperature as the intake air temperature from the inside of the room. Even if the opening is reduced, the temperature does not change any further. That is, the superheat area remains expanded in the auxiliary indoor heat exchanger 7, which should originally be the evaporation area,
In addition, since the opening degree of the electric expansion valve 24 is narrowed, there is a possibility that the dehumidifying action may not be obtained.

However, when entering such an over-throttled state,
As shown in FIG. 5, the detected temperature Tcj of the heat exchanger temperature sensor 13 changes in an increasing direction, while the detected temperature Tc of the heat exchanger temperature sensor 14 changes less than a predetermined value, and the first determination condition Is satisfied (YES in step 112). In other words, it is determined that the drawing is overdrawn. Then, as over-throttle protection, the opening degree correction of the electric expansion valve 24 is increased by 5 pulses (step 114).

When the over-throttled state is entered, the difference between the temperature Ta detected by the indoor temperature sensor 15 and the temperature Tcj detected by the heat exchanger temperature sensor 13 becomes a predetermined value or less, so that as shown in FIG. The second judgment condition is satisfied (step 113
YES). In other words, it is determined that the drawing is overdrawn. Then, as over-throttle protection, the opening degree correction of the electric expansion valve 24 is increased by 15 pulses (step 115). When the second determination condition is satisfied, the degree of over-throttlement is large, and the opening correction amount is set to be larger than when the first determination condition is satisfied in order to perform quick protection. .

When the auxiliary indoor heat exchanger 7 and the main indoor heat exchanger 8 are viewed as one heat exchanger, it is shown in FIG. 6, FIG. 7, and FIG. Is shown in.

In FIG. 6, the overheat region extends to the auxiliary indoor heat exchanger 7, which corresponds to an over-throttled state. FIG. 7 shows a state in which the evaporation region has expanded to the main indoor heat exchanger 8 side. This Figure 6
7 and FIG. 7 are both inappropriate, and the situation of FIG. 6 shifts to the proper state shown in FIG. 8 due to the detection of over-aperture and over-aperture protection. The situation of FIG. 7 shifts to the proper state of FIG. 8 by superheat control.

On the other hand, regarding the superheat control, it is determined whether the refrigeration cycle is in the transient period or in the stable period, and if it is in the transient period, the correction amount of the opening is increased to three times the correction amount in the stable period. (Steps 116 and 117), the rise of the dehumidifying action is improved. In the stable period, the correction amount of the opening is not increased, so that the stability of the indoor temperature is improved.

In the dehumidifying operation, the vertical louvers 11 and 11 are set slightly upward from the horizontal as shown by the broken line in FIG. 3 so that a short circuit in which blown air is sucked from the suction port is formed. Good. Due to the formation of this short circuit, dehumidification can be performed without allowing the wind from the outlet to reach the living area, and comfortable dehumidification without a feeling of cold wind becomes possible.

(2) Heating operation mode In the heating operation mode, as shown in the flowchart of FIG. 9, the four-way valve 22 is switched (step 201) to form the heating cycle.

The difference ΔT (= Ta-Ts) between the detected temperature Ta of the room temperature sensor 15 and the set temperature Ts is obtained (step 202). Then, according to the temperature difference ΔT, the compressor 21
The operating frequency F is controlled (step 203).

The target superheat amount SHo for the heating operation is determined (step 204), and the suction refrigerant temperature Tsuc detected by the refrigerant temperature sensor 16 and the outdoor heat exchanger 23 detected by the heat exchanger temperature sensor 17 are determined. The difference from the temperature Te (= Tsuc-Te) is captured as the superheat amount SHa (step 205).

A difference SHd (= SHo-SHa) between the target superheat amount SHo and the actual superheat amount SHa is obtained (step 206). Also, SHd and the previous SH
The difference ΔSH with d (= SHd-previous SHd) is calculated (step 207). Then, the current SHd and the difference Δ
The opening correction amount ΔPLS with respect to the current opening of the electric expansion valve 24 is obtained by a function using SH (step
208).

As the heating over-throttle detection, it is determined whether the difference (= Tc-Ta) between the temperature Tc detected by the heat exchanger temperature sensor 14 and the temperature Tc detected by the indoor temperature sensor 15 is equal to or less than a predetermined value T ₁ ( Step 209). Two types of high and low are prepared as the predetermined value T ₁ , and in order to accurately perform over-throttle detection, if the operating frequency F of the detection compressor 21 is higher than a certain value, the higher predetermined value T ₁ is selected, and the operating frequency is selected. If F is lower than a certain value, the lower predetermined value T ₁ is selected.

If the judgment is not satisfied (step 209:
NO), the opening of the electric expansion valve 24 is actually corrected by the opening correction amount ΔPLS under the judgment that the throttle valve is not over-throttled (step 210).

The determination is satisfied (YES in step 209),
Moreover, if the satisfaction state continues for a predetermined time based on the time count t ₁ , for example, 2 minutes or more (steps 211, 212).
), After the time count t ₁ is cleared (step 2
13) Then, the calculated opening correction amount ΔPLS is increased by a predetermined opening amount, for example, 30 pulses (step 214). Then, the opening of the electric expansion valve 24 is actually corrected by the opening correction amount ΔPLS (step 215).

After this opening correction, the temperature difference (= Tc-T
Whether a) continues to be equal to or less than the predetermined value T ₁ ,
It is determined (step 216). If it continues (YES in step 216), the opening degree correction amount ΔPLS is calculated every predetermined time tx based on the time count t ₂ (steps 217 and 218).
Is increased by 30 pulses of a predetermined opening amount and is actually corrected (steps 214 and 215). This opening degree correction is repeated until the temperature difference (= Tc-Ta) becomes equal to or greater than the predetermined value T ₁ , that is, until the over-throttled state is resolved. The time count t ₂ is sequentially cleared (step 219).

During the heating operation, the over-throttle detection is appropriate by performing the over-throttle detection by using the indoor temperature Ta and Tc of the main indoor heat exchanger 8 which can secure a sufficient temperature difference. In addition to this, since over-throttle protection is performed, superheat control becomes appropriate and a stable heating action can be obtained.

(3) Cooling operation mode In the cooling operation in which both the auxiliary indoor heat exchanger 7 and the main indoor heat exchanger 8 function as evaporators, the suction refrigerant temperature T
The difference (= Tsuc-Tcj) between suc and the temperature Tcj detected by the heat exchanger temperature sensor 13 is captured as the superheat amount SHa, and the target superheat amount SHo for the cooling operation is obtained.
The opening degree of the electric expansion valve 24 is superheat-controlled in accordance with the difference SHd (= SHo-SHa) between and.

The over-throttle detection may be performed based on the difference between the temperature Tc detected by the heat exchanger temperature sensor 14 and the temperature Tj detected by the heat exchanger temperature sensor 13, as in the dehumidifying operation.
Alternatively, it may be performed based on the difference between the indoor temperature Ta and the temperature Tc detected by the heat exchanger temperature sensor 14. Then, when detecting the over-throttled state, over-throttle protection is executed in the same manner as the dehumidifying operation and the heating operation. As a result, superheat control becomes appropriate and a stable cooling action can be obtained.

(B) Next, a second embodiment of the present invention will be described. In step 112 in the first embodiment, "first"
"Over throttle detection of" and "Second over throttle detection" of step 113 are effective for the air conditioner in which the operable range of the outdoor temperature is not so wide.

However, an air conditioner designed to expand the operable range of the indoor and outdoor temperatures, for example, the operable range of the indoor temperature expands to the low temperature side, and the operable range of the outside air temperature increases to the high temperature side. In the spread air conditioner,
There is a possibility that an error may occur in the "first over-aperture detection" or the "second over-aperture detection".

For example, in the dehumidifying operation under the condition that the indoor temperature is low and the outdoor air temperature is high, the outdoor heat exchanger (condenser)
The temperature of the refrigerant flowing from 23 does not drop easily, and the refrigerant having a temperature higher than the indoor temperature flows into the auxiliary indoor heat exchanger 7 at the beginning of the operation. In this case, since the refrigerant does not evaporate in the auxiliary indoor heat exchanger 7, the temperature Tcj of the auxiliary indoor heat exchanger 7 is increased.
(Evaporation zone temperature), temperature Tc of the main indoor heat exchanger 8 (overheat zone temperature), and room temperature Ta are substantially the same. Moreover, since the capacity of the compressor 21 is set to a low level (the operating frequency F is low) during the dehumidifying operation, it takes a long time before the difference between the evaporation zone temperature Tcj, the superheat zone temperature Tc, and the indoor temperature Ta occurs. It takes time.

Under these circumstances, the evaporation zone temperature Tcj
There is an error in the "first over-throttle detection" which detects the over-throttle based on the change of the Is likely to occur.

If an error is detected in over-throttle detection, the opening of the electric expansion valve 24 is unnecessarily increased, and it takes an extremely long time for the refrigeration cycle to reach the optimum state for the dehumidifying operation.

In order to cope with such a problem, in the second embodiment, the following [22] is added as the functional means of the control unit 40 to [1] to [21] in the first embodiment.
The other structure is the same as that of the first embodiment.

[22] Based on the difference ΔTao (= Ta-To) between the indoor temperature Ta detected by the indoor temperature sensor 15 and the outdoor air temperature To detected by the outdoor air temperature sensor 18, the first and second over-throttlements are performed. Discriminating means for discriminating whether or not the detection by the detecting means is effective. Specifically, the outside air temperature To is subtracted from the indoor temperature Ta to obtain the temperature difference ΔTao, and when the temperature difference ΔT is equal to or larger than a predetermined value X (negative value), it is determined that the over-throttle detection is effective.

As for the operation, as shown in the flow chart of FIG. 10, step 111 and step 111 in the first embodiment are performed.
Between 112 and 112
0 is added.

Over / Aperture Detection Effective / Ineffective Discrimination Routine 300
Corresponds to the above-mentioned [22] discriminating means and comprises steps 301 to 306 shown in FIG. First, the flag flag _{1, which} is an indicator of whether over-aperture detection is valid or invalid, is "1".
Or "0" is determined (step 301). Note that the flag
flag ₁ is initially set to "0" at the start of operation.

If the flag flag _{1 is} still "0" (NO in step 301), the detected temperature Ta of the indoor temperature sensor 15 and the detected temperature To of the outside air temperature sensor 18 are read (steps 302 and 303).

The temperature difference ΔTao (= Ta-To) is obtained by subtracting the detection temperature To from the detection temperature Ta (step 304), and the temperature difference ΔTao is compared with the predetermined value X (negative value). (Step 305).

If the temperature difference ΔTao is greater than or equal to the predetermined value X (YES in step 305), the first step of step 112 in the subsequent stage is performed.
Over-aperture detection ”and step 113“ Second over-aperture detection ”
If it is determined that the flag is valid, the flag flag ₁ is set to "1" (step 306). After this, step 112
Move to.

When the flag flag ₁ becomes "1" (step
301 YES), and thereafter steps for determining valid / invalid
The process proceeds from step 302 to step 112 without going through step 306.

However, when the temperature difference ΔTao is less than the predetermined value X (NO in step 305), it is determined that the "first over-throttle detection" and "second over-throttle detection" in the subsequent stages are invalid. Below, the flag flag ₁ remains "0", and the process proceeds to step 116 while bypassing steps 112 and 113.

If the flag flag ₁ remains "0" (NO in step 301), the subsequent steps for determining validity / invalidity.
302 to step 306 are repeatedly executed. Figure 12
Room temperature Ta and evaporation zone temperature T after a certain period of time from the start of operation
This is the data confirmed by experiments using the temperature difference ΔTao as a parameter for the relationship with cj.

That is, in a region where the indoor temperature Ta is low, the outside air temperature To is high, and the temperature difference ΔTao is less than a predetermined value X (negative value), the evaporation zone temperature Tcj is higher than the indoor temperature Ta or the evaporation zone temperature Tcj is higher than the indoor temperature Ta. The temperature Tcj is slightly lower than the indoor temperature Ta.

As described above, in the dehumidifying operation under the condition that the indoor temperature is low and the outdoor air temperature is high, the temperature of the refrigerant flowing out from the outdoor heat exchanger (condenser) 23 does not decrease easily, and the initial operation is started. The reason is that the refrigerant having a temperature higher than the indoor temperature flows into the auxiliary indoor heat exchanger 7. Since the refrigerant that has flowed in does not evaporate in the auxiliary indoor heat exchanger 7, the evaporation zone temperature Tcj, the superheat zone temperature Tc, and the room temperature Ta are substantially the same. Moreover, since the capacity of the compressor 21 is set to a low level (the operating frequency F is low) during the dehumidifying operation, it takes a long time until a difference occurs between the evaporation zone temperature Tcj, the superheat zone temperature Tc, and the indoor temperature Ta. It will cost you.

Under these circumstances, the evaporation zone temperature Tcj
There is an error in the "first over-throttle detection" which detects the over-throttle based on the change of the Will occur.

Therefore, the temperature difference ΔTao that may cause an erroneous detection.
In a region where is less than the predetermined value X, over-throttle detection is invalidated to avoid unnecessary increase in valve opening. And the temperature difference Δ
After Tao becomes equal to or larger than the predetermined value X and there is no fear of erroneous detection, over-aperture detection is made effective.

By such control, over-throttle detection for appropriately setting the region setting of the evaporation region (main indoor heat exchanger 7) and the overheating region (auxiliary indoor heat exchanger 8) together with the superheat control, the indoor and outdoor temperature is detected. It can be performed properly regardless of the expansion of the operable range and the reliability can be improved.

(C) A third embodiment of the present invention will be described. An air conditioner designed to expand the operable range of the indoor and outdoor temperatures, for example, an air conditioner in which the operable range of the indoor temperature expands to the low temperature side and the operable range of the outside air temperature expands to the high temperature side. Then, there is a possibility that an error may occur in the "first over-aperture detection" or the "second over-aperture detection".

For example, the dehumidifying operation under the condition that the outside air temperature is low is a so-called start-up operation in which the compressor 21 is started in a state where the liquid refrigerant is accumulated in the outdoor heat exchanger 23 and the pipes around it. Moreover, during the dehumidifying operation, the compressor 21
Is set to a low level (the operating frequency F is low), it takes time for the refrigerant to flow into the auxiliary indoor heat exchanger 7, which in turn lowers the temperature Tcj (evaporation zone temperature) of the auxiliary indoor heat exchanger 7. Will take time. During this period, the evaporation zone temperature Tcj, the superheat zone temperature Tc, and the room temperature Ta are kept substantially the same.

Under such a situation, the superheat region temperature Tc
There is an error in the "first over-throttle detection" which detects the over-throttle based on the change of the Is likely to occur.

In order to cope with such a problem, in the third embodiment, the following [23] is added to [1] to [21] in the first embodiment as the functional means of the control unit 40.
The other structure is the same as that of the first embodiment.

[23] Difference ΔTccj (= Tc-Tcj, superheat amount SHa) between the overheat zone temperature Tc detected by the heat exchanger temperature sensor 14 and the evaporation zone temperature Tcj detected by the heat exchanger temperature sensor 13. ), The determination means determines whether or not the detection by the first and second over-throttle detection means is effective.
Specifically, the temperature difference ΔTccj is obtained by subtracting the evaporation region temperature Tcj from the overheat region temperature Tc, and it is determined that the over-throttle detection is effective after the temperature difference ΔTccj becomes equal to or more than the predetermined value Y.

As for the operation, as shown in the flow chart of FIG. 10, step 111 and step 111 in the first embodiment are performed.
Between 112 and 112
0 is added.

Over / Aperture Detection Effective / Ineffective Discrimination Routine 300
Corresponds to the above-mentioned [23] discriminating means and comprises steps 401 to 406 shown in FIG. First, the flag flag _{1, which} is an indicator of whether over-aperture detection is valid or invalid, is "1".
Or "0" is determined (step 401). Note that the flag
flag ₁ is initially set to "0" at the start of operation.

If the flag flag _{1 is} still "0" (NO in step 401), the superheat zone temperature Tc detected by the heat exchanger temperature sensor 14 and the evaporation zone temperature Tcj detected by the heat exchanger temperature sensor 13 are detected. Is read (steps 402, 403)
).

The temperature difference ΔTccj (= Tc-Tcj, which corresponds to the superheat amount) is obtained by subtracting the evaporation region temperature Tcj from the overheating region temperature Tc (step 404), and the temperature difference ΔTccj and the predetermined value Y are obtained. Compared (step 40)
Five ).

If the temperature difference ΔTccj is equal to or larger than the predetermined value Y (YES in step 405), the first step of step 112 in the subsequent stage is performed.
Over-aperture detection ”and step 113“ Second over-aperture detection ”
If it is determined that is valid, the flag flag ₁ is set to "1" (step 406). After this, step 112
Move to.

When the flag flag ₁ becomes "1" (step
401 YES), and thereafter steps for determining valid / invalid
The process proceeds from step 402 to step 112 without passing through step 406.

However, if the temperature difference ΔTccj is less than the predetermined value Y (NO in step 405), the "first" in step 112 is selected.
Over-aperture detection ”and step 113“ Second over-aperture detection ”
Is judged to be invalid, the flag flag ₁ remains "0" and the process proceeds to step 116 while bypassing step 112 and step 113.

If the flag flag ₁ remains "0" (NO in step 401), the steps for determining validity / invalidity are performed thereafter.
Steps 402 to 406 are repeatedly executed. Figure 14
It is data obtained by confirming the relationship among the room temperature Ta, the superheat region temperature Tc, and the evaporation region temperature Tcj after the dehumidifying operation is started by experiments.

That is, in the dehumidifying operation under the condition where the outside air temperature is low, the superheat region temperature Tc, the evaporation region temperature Tcj, and the room temperature Ta are kept substantially the same at the start of the operation.

As described above, in the dehumidifying operation under the condition that the outside air temperature is low, the compressor 21 is started in a state where the liquid refrigerant is accumulated in the outdoor heat exchanger 23 and the pipes around it, that is, the so-called bed start-up. Therefore, the capacity of the compressor 21 is set to be low (the operating frequency F is low) during the dehumidifying operation. It takes time for the refrigerant to flow into the auxiliary indoor heat exchanger 7, and thus it takes time for the temperature Tcj (evaporation region temperature) of the auxiliary indoor heat exchanger 7 to decrease. During this time, the evaporation region temperature Tcj, the superheat region temperature Tc, The indoor temperature Ta will be maintained in substantially the same state.

Under such a situation, the superheat region temperature Tc
There is an error in the "first over-throttle detection" which detects the over-throttle based on the change of the Will occur.

Therefore, after the operation is started, during a period in which the difference ΔTccj between the superheat region temperature Tc and the evaporation region temperature Tcj is less than the predetermined value Y,
That is, the change in the evaporation zone temperature Tcj is small and the "first over throttling detection" error occurs, and the difference between the room temperature Ta and the evaporation zone temperature Tcj is small, and the "second over throttling detection" error occurs. During the gaining period, over-throttle detection is invalidated to avoid an unnecessary increase in valve opening. Then, after the temperature difference ΔTccj opens above the predetermined value Y and there is no fear of erroneous detection, the over-throttle detection is made effective.

By such control, over-throttle detection for appropriately setting the area setting of the evaporation area (main indoor heat exchanger 7) and the overheating area (auxiliary indoor heat exchanger 8) together with the superheat control, the indoor / outdoor temperature is detected. It can be performed properly regardless of the expansion of the operable range and the reliability can be improved.

(D) A fourth embodiment of the present invention will be described. The fourth embodiment is a combination of the second embodiment and the third embodiment, and as the functional means of the control unit 40, [1] to [21] in the first embodiment are followed by the following [22]. [23] is added. The other structure is the same as that of the first embodiment.

[22] Based on the difference ΔTao between the room temperature Ta detected by the room temperature sensor 15 and the outside air temperature To detected by the outside air temperature sensor 18, the detection of the first and second over-throttle detection means is effective. First determining means for determining whether or not. Specifically, the temperature difference ΔTao is obtained by subtracting the outside air temperature To from the room temperature Ta, and the temperature difference ΔT is a predetermined value X (negative value).
In the above cases, it is determined that the excessive aperture detection is effective.

[23] Difference ΔTccj (= Tc-Tcj, superheat amount SHa) between the superheat region temperature Tc detected by the heat exchanger temperature sensor 14 and the evaporation region temperature Tcj detected by the heat exchanger temperature sensor 13. ), The second determination means for determining whether or not the detections of the first and second over-aperture detection means are valid. Specifically, the temperature difference ΔTccj is obtained by subtracting the evaporation region temperature Tcj from the overheat region temperature Tc, and it is determined that the over-throttle detection is effective after the temperature difference ΔTccj becomes equal to or more than the predetermined value Y.

Regarding the operation, as shown in the flowchart of FIG. 10, step 111 and step 111 in the first embodiment are performed.
Between 112 and 112
0 is added.

Over / Aperture Detection Effective / Ineffective Discrimination Routine 300
Corresponds to the first and second discriminating means described above, and FIG.
Step 301-Step 306 and Step 402-shown in FIG.
It consists of step 406.

First, it is judged whether the flag flag _{1, which} is an indicator of whether over-aperture detection is valid or invalid, is "1" or "0" (step 301). The flag flag ₁ is initialized to "0" at the start of operation.

If the flag flag _{1 is} still "0" (NO in step 301), the detected temperature Ta of the indoor temperature sensor 15 and the detected temperature To of the outside air temperature sensor 18 are read (steps 302 and 303).

By subtracting the detected temperature To from the detected temperature Ta, the temperature difference ΔTao (= Ta-To) is obtained (step 304), and the temperature difference ΔTao is compared with the predetermined value X (negative value). (Step 305).

If the temperature difference ΔTao is greater than or equal to the predetermined value X (YES in step 305), the first step in step 112 in the subsequent stage is performed.
Over-aperture detection ”and step 113“ Second over-aperture detection ”
If it is determined that the flag is valid, the flag flag ₁ is set to "1" (step 306). After this, step 112
Move to.

When the flag flag ₁ becomes "1" (step
301 YES), and thereafter steps for determining valid / invalid
302 to step 306 and step 402 to step 406
Transition to step 112 without passing.

However, when the temperature difference ΔTao is less than the predetermined value X (NO in step 305), the flag flag ₁ remains “0” and the overheat region temperature Tc and the heat detected by the heat exchanger temperature sensor 14 are kept. The evaporation zone temperature Tcj detected by the exchanger temperature sensor 13 is read (steps 402, 403).

The temperature difference ΔTccj (= Tc-Tcj) is obtained by subtracting the evaporation region temperature Tcj from the superheat region temperature Tc (step 404), and the temperature difference ΔTccj is compared with the predetermined value Y (step). 405).

If the temperature difference ΔTccj is equal to or larger than the predetermined value Y (YES in step 405), the first step in step 112 in the subsequent stage is performed.
Over-aperture detection ”and step 113“ Second over-aperture detection ”
If it is determined that is valid, the flag flag ₁ is set to "1" (step 406). After this, step 112
Move to.

However, if the temperature difference ΔTccj is less than the predetermined value Y (NO in step 405), the "first" in step 112 is selected.
Over-aperture detection ”and step 113“ Second over-aperture detection ”
Is judged to be invalid, the flag flag ₁ remains "0" and the process proceeds to step 116 while bypassing step 112 and step 113.

If the flag flag ₁ remains "0" (NO in step 301), the subsequent steps for determining validity / invalidity.
302 to step 306 and step 402 to step 406
Is repeatedly executed.

As described above, in a region where the temperature difference ΔTao is less than the predetermined value X, the over-throttle detection is disabled to avoid an unnecessary increase in the valve opening degree, and after the operation is started, the temperature difference ΔTccj is a region where the temperature difference ΔTccj is less than the predetermined value Y. In this case, the over-throttle detection is disabled to avoid an unnecessary increase in the valve opening degree, so that the area settings of the evaporation area (main indoor heat exchanger 7) and the overheating area (auxiliary indoor heat exchanger 8) can be appropriately set together with the superheat control. Over-throttle detection to do
Despite the expansion of the operable range of the indoor and outdoor temperatures, it can be performed properly and the reliability can be improved.

(E) The fifth embodiment of the present invention will be described. In the fifth embodiment, as the functional means of the control unit 40,
The following [24] is added to [1] to [21] in the case of the first embodiment. The other structure is the same as that of the first embodiment.

[24] Discriminating means for discriminating whether or not the detection of the first and second over-throttlement detecting means is effective based on the evaporation zone temperature Tcj detected by the heat exchanger temperature sensor 13. Specifically, it is determined that the over-throttle detection is effective after the evaporation zone temperature Tcj becomes equal to or lower than the predetermined value Z.

Regarding the operation, as shown in the flow chart of FIG. 10, step 111 and step 111 in the first embodiment are performed.
Between 112 and 112
0 is added.

Over / Aperture Detection Effective / Ineffective Discrimination Routine 300
Corresponds to the above-mentioned [24] discriminating means and comprises steps 501 to 504 shown in FIG. First, the flag flag _{1, which} is an indicator of whether over-aperture detection is valid or invalid, is "1".
Or "0" is determined (step 501). Note that the flag
flag ₁ is initially set to "0" at the start of operation.

If the flag flag _{1 is} still "0" (NO in step 501), the evaporation zone temperature Tcj detected by the heat exchanger temperature sensor 13 is read (step 502). This evaporation zone temperature Tcj is compared with a predetermined value Z (step 503).
).

FIG. 1 shows the relationship between the evaporation zone temperature Tcj and the predetermined value Z.
It is shown in FIG. If the evaporation zone temperature Tcj is equal to or lower than the predetermined value Z (YES in step 503), the "first over-throttle detection" in step 112 and the "second over-throttle detection" in step 113 are effective. Then, the flag flag ₁ is set to "1" (step 504). After this, the process proceeds to step 112.

When the flag flag ₁ becomes "1" (step
501 YES), and then steps for determining valid / invalid
The process proceeds to step 112 without going through steps 502 to 504.

However, when the temperature difference ΔTccj is larger than the predetermined value Z (NO in step 503), the “first over-throttle detection” in step 112 and the “second over-throttle detection” in step 113 are invalid. If it is determined that the flag is present, the flag flag ₁ remains "0", and the process proceeds to step 116 while bypassing steps 112 and 113.

If the flag flag ₁ remains "0" (NO in step 501), the subsequent steps for determining validity / invalidity.
Steps 502 to 504 are repeatedly executed. In this way, after the start of operation, during the period when the evaporation zone temperature Tcj is higher than the predetermined value Z, the change in the evaporation zone temperature Tcj is still small and an error occurs in the "first over-throttle detection", or the room temperature Ta and evaporation. Under the judgment that the difference between the temperature Tcj and the zone temperature Tcj is still small and the "second over-throttle detection" may be erroneous, the over-throttle detection is disabled to avoid an unnecessary increase in the valve opening. . Then, after the evaporation zone temperature Tcj becomes equal to or lower than the predetermined value Z and there is no fear of erroneous detection, the over-throttle detection is made effective.

With such control, over-throttle detection for appropriately setting the area setting of the evaporation area (main indoor heat exchanger 7) and the overheating area (auxiliary indoor heat exchanger 8) together with the superheat control, the indoor / outdoor temperature is detected. It can be performed properly regardless of the expansion of the operable range and the reliability can be improved.

In the fifth embodiment, the evaporation zone temperature Tcj is used as a determining element for determining whether or not the over-throttle detection is effective, but the overheating zone temperature Tc may be used instead of the evaporation zone temperature Tcj. In this case, the over-throttle detection is determined to be valid after the overheat region temperature Tc becomes equal to or lower than the predetermined value Z.

(F) A sixth embodiment of the present invention will be described. In the fifth embodiment, as the functional means of the control unit 40,
The following [25] is added to [1] to [21] in the case of the first embodiment. The other structure is the same as that of the first embodiment.

[25] Discriminating means for discriminating whether or not the detection by the first and second over-throttlement detecting means is effective based on the evaporation zone temperature Tcj detected by the heat exchanger temperature sensor 13. Specifically, it is determined that the over-throttle detection is effective after the change in the evaporation zone temperature Tcj changes from a decrease to an increase.

As for the operation, as shown in the flow chart of FIG. 10, step 111 and step 111 in the first embodiment are performed.
Between 112 and 112
0 is added.

Over / Aperture Detection Effective / Ineffective Discrimination Routine 300
Corresponds to the discrimination means in [25] above and comprises steps 601 to 610 shown in FIG. First, the flag flag _{1, which} is an indicator of whether over-aperture detection is valid or invalid, is "1".
Or "0" is determined (step 601). Note that the flag
flag ₁ is initially set to "0" at the start of operation.

If the flag flag _{1 is} still "0" (NO in step 601), it is judged whether the temperature reading number n is "0" (step 602). The temperature reading number n is cleared to "0" at the start of the operation.

If the temperature reading number n is still "0" (YES in step 602), the evaporation zone temperature Tcj detected by the heat exchanger temperature sensor 13 is read (step 604), and the evaporation zone temperature Tcj is read. It is stored as Tcj (0) (step
605).

When the time count t ₁ is started (step 606), the temperature reading number n is increased by "1" (step 607), and the temperature reading number n (= "1") is set value "3" or more. It is determined whether or not (step 608)
).

In this case, since the temperature reading number n has not reached the set value "3" yet (NO in step 608), the "first over throttle detection" in step 112 and the "second over throttle" in step 113 are performed. If the flag "Detected" is invalid,
Flag ₁ remains "0", and step 112 and step 11
Go to step 116, bypassing step 3.

When the temperature reading number n becomes "1" (NO in step 602), it is determined whether or not the time count t ₁ has reached the set time ts (for example, 10 to 20 seconds) (step 603).

If the time count t ₁ does not reach the set time ts (NO in step 603), the shift to step 116 continues. When the time count t ₁ reaches the set time ts (YES in step 603), the evaporation zone temperature Tcj is read again (step 604), and the evaporation zone temperature Tcj is Tcj.
It is stored as (1) (step 605).

The time count t ₁ is restarted (step 606), the temperature reading number n is increased by "1" (step 607), and whether the temperature reading number n (= "2") is the set value "3" or more. It is judged (step 608).

In this case, since the temperature reading number n has not yet reached the set value "3" (NO in step 608), the "first over throttle detection" in step 112 and the "second over throttle" in step 113 are performed. If the flag "Detected" is invalid,
Flag ₁ remains "0", and step 112 and step 11
Go to step 116, bypassing step 3.

In this way, the evaporation zone temperature Tcj is read and stored at every set time ts, and when the number of temperature readings n reaches the set value "3" (YES in step 608), the 3 stored by then. Batch evaporation temperature Tcj (n-2), Tcj (n
-1) and Tcj (n) are compared with each other (step 609).

If there is a relation of Tcj (n-2)> Tcj (n-1) <Tcj (n) (YES in step 609), that is, when the change of the evaporation zone temperature Tcj changes from decrease to increase. After that, the flag flag ₁ is set to "1" under the judgment that the "first over-aperture detection" in the step 112 and the "second over-aperture detection" in the step 113 are effective after that. (Step 610). The time count t ₁ is reset. After this, the process proceeds to step 112.

As described above, after the operation is started, the evaporation zone temperature Tcj
If there is a risk that an error may occur in the "first over-throttle detection" or "second over-throttle detection" while the change in the Avoid growth. Then, after the change of the evaporation zone temperature Tcj changes from the decrease to the increase and there is no fear of erroneous detection, the over-throttle detection is made effective.

By such control, over-throttle detection for appropriately setting the area setting of the evaporation area (main indoor heat exchanger 7) and the overheating area (auxiliary indoor heat exchanger 8) together with the superheat control is performed. It can be performed properly regardless of the expansion of the operable range and the reliability can be improved.

In the sixth embodiment, the evaporation zone temperature Tcj is used as a determining element for determining whether or not the over-throttle detection is effective, but the overheating zone temperature Tc may be used instead of the evaporation zone temperature Tcj. In this case, after the change in the overheat region temperature Tc changes from the decrease to the increase, it is determined that the over-throttle detection is effective.

(G) A seventh embodiment of the present invention will be described. In the seventh embodiment, as the functional means of the control unit 40,
The following [26] to [29] are added to [1] to [21] in the first embodiment. The other structure is the same as that of the first embodiment.

[26] Based on the opening Q of the electric expansion valve 24,
A first discriminating unit that discriminates whether or not the detections of the first and second excessive aperture detection units are valid. Specifically, it is determined that the electric expansion valve 24 is effective after the opening amount Qo at the start of operation is reduced by a predetermined opening amount Qn or more.

[27] Predetermined opening Qn in the first discriminating means
Is a control means for variably setting the temperature of the indoor temperature sensor 15 and a temperature of the outdoor air temperature sensor 18 which is difference ΔTao (Ta-Ts).

[28] Second discriminating means for discriminating whether or not the detection by the first and second over-throttlement detecting means is effective based on the elapsed time to from the start of operation. Specifically, it is determined to be valid after the elapsed time to from the start of operation reaches the predetermined time tn.

[29] Predetermined time tn in the second discriminating means
Is a control means for variably setting the temperature of the indoor temperature sensor 15 and a temperature of the outdoor air temperature sensor 18 which is difference ΔTao (Ta-Ts).

As for the operation, as shown in the flowchart of FIG. 10, step 111 and step in the first embodiment are performed.
Between 112 and 112
0 is added.

Over-Aperture Detection Effective / Ineffective Discrimination Routine 300
Corresponds to the functions of [26] to [29] above.
Steps 701 to 709 shown in FIG. First, it is determined whether the flag flag _{1, which} is an indicator of whether over-aperture detection is valid or invalid, is "1" or "0" (step 701). In addition,
The flag flag ₁ is initialized to "0" at the start of operation.

If the flag flag _{1 is} still "0" (NO in step 701), the detected temperature Ta of the indoor temperature sensor 15 and the detected temperature To of the outside air temperature sensor 18 are read (steps 702, 703).

By subtracting the detected temperature To from the detected temperature Ta, the temperature difference ΔTao (= Ta-To) is obtained (step 704), and the predetermined time tn and the predetermined opening Qn are changed according to the temperature difference ΔTao. Set (Step 70)
Five ). This variable setting is made as follows. The opening degree is represented by the number of drive pulses supplied to the electric expansion valve 24.

Predetermined value X (negative value described in the second embodiment)
When ≦ ΔTao, tn = 20 minutes, Qn = 40 pulses. When X ≦ ΔTao <−30 deg, tn = 0 minutes, Qn = 0 pulse. When -30deg ≤ ΔTao <-20deg, tn = 0 minutes, Qn = 0 pulse. When -20deg ≤ ΔTao <-10deg, tn = 3 minutes, Qn = 5 pulses. When -10deg ≤ ΔTao <0deg, tn = 5 minutes, Qn = 10 pulses. When -10deg ≤ ΔTao <0deg, tn = 5 minutes, Qn = 10 pulses. When 0deg ≤ ΔTao <10deg, tn = 10 minutes, Qn = 20 pulses. When 10deg ≤ ΔTao <20deg, tn = 15 minutes, Qn = 30 pulses. When 20deg ≤ ΔTao <30deg, tn = 20 minutes, Qn = 40 pulses.

ΔTao becomes a negative value when the outside air temperature To is higher than the room temperature Ta, and ΔTao becomes a positive value when the outside air temperature To is lower than the room temperature Ta. During a period in which the elapsed time to from the start of operation has not reached the predetermined time tn yet (NO in step 706), the current opening Q is subtracted from the initial opening Qo at the start of the operation of the electric expansion valve 24 to change the opening. ΔQ (= Qo-Q) is obtained (step 707). Then, it is determined whether the opening change ΔQ is equal to or larger than the predetermined opening Qn (step 708).

If the opening change ΔQ does not reach the predetermined opening Qn (NO in step 708), the “first over-throttle detection” in step 112 and the “second over-throttle detection” in step 113 are invalid. If it is determined that there is, the flag flag ₁ remains “0”, and bypasses step 112 and step 113.
Go to step 116.

When the opening change ΔQ reaches the predetermined opening Qn (YES in step 708, refer to FIG. 14), thereafter, the first over-throttle detection in step 112 in the subsequent stage and step 113.
Based on the judgment that the "second over-aperture detection" of is effective,
Flag flag ₁ is set to "1" (step 709)
). After this, the process proceeds to step 112.

When the elapsed time to from the start of operation reaches the predetermined time tn (YES in step 706, see FIG. 14), the flag flag ₁ is set to "1" regardless of the opening change ΔQ ( Step 709), Step 112
Move to.

As described above, after the operation is started, the electric expansion valve 24
If the opening degree Q of is not throttled by a predetermined opening degree Qn or more or the predetermined time tn has not elapsed, there is a possibility that an error may occur in the "first over-throttle detection" or the "second over-throttle detection". Under this judgment, the over-throttle detection is invalidated to avoid an unnecessary increase in the valve opening. Then, after the opening Q of the electric expansion valve 24 is narrowed down by a predetermined opening Qn or more, or after a predetermined time tn has elapsed from the start of operation and there is no fear of erroneous detection, over-throttle detection is made effective. .

By such control, the over-throttle detection for appropriately setting the area setting of the evaporation area (main indoor heat exchanger 7) and the overheating area (auxiliary indoor heat exchanger 8) together with the superheat control, the indoor / outdoor temperature. It can be performed properly regardless of the expansion of the operable range and the reliability can be improved.

Especially, the predetermined time tn and the predetermined opening Qn
Is the difference ΔTao between the indoor temperature Ta and the outside air temperature To.
Since it is variably set according to the above, it is possible to detect the over-throttle in consideration of the actual driving situation.

[0228]

As described above, the air conditioners of the first and second aspects of the present invention can appropriately set the evaporating region and the superheat region in the indoor heat exchanger during dehumidification together with superheat control. , thereby with stable dehumidifying effect can be reliably obtained without lowering the indoor temperature, dehumidification
It improves the rise of action and the stability of room temperature.
Can be achieved.

[0229]

[0230]

[0231]

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a refrigeration cycle and a configuration of a control circuit of each embodiment.

FIG. 2 is a diagram showing a configuration of a specific example of the electric expansion valve of each embodiment.

FIG. 3 is a cross-sectional view showing the internal configuration of the indoor unit of each example.

FIG. 4 is a flow chart for explaining the operation during the dehumidifying operation of the first embodiment.

FIG. 5 is a diagram showing a relationship between changes in detected temperatures Tc and Tcj during dehumidification operation and over-throttle detection according to the embodiment.

FIG. 6 is a diagram showing an example of how the phase change of the refrigerant becomes when the auxiliary indoor heat exchanger and the main indoor heat exchanger of each embodiment are viewed as one heat exchanger.

FIG. 7 is a diagram showing another example of how the phase change of the refrigerant becomes when the auxiliary indoor heat exchanger and the main indoor heat exchanger of each embodiment are viewed as one heat exchanger.

FIG. 8 is a diagram showing an appropriate example of how the phase change of the refrigerant becomes when the auxiliary indoor heat exchanger and the main indoor heat exchanger of each embodiment are viewed as one heat exchanger.

FIG. 9 is a flowchart for explaining the operation of each embodiment during heating operation.

FIG. 10 is a flowchart for explaining the operation during the dehumidifying operation of the second to seventh embodiments.

FIG. 11 is a flowchart showing a valid / invalid determination routine of over-aperture detection in the second embodiment.

FIG. 12 is a diagram showing the relationship between the indoor temperature Ta and the evaporation zone temperature Tcj in each example, using the temperature difference ΔTao as a parameter.

FIG. 13 is a flowchart showing a valid / invalid determination routine of over-aperture detection in the third embodiment.

FIG. 14 is a diagram showing a relationship among an indoor temperature Ta, an overheating zone temperature Tc, and an evaporation zone temperature Tcj in each example.

FIG. 15 is a flowchart showing a valid / invalid determination routine of over-aperture detection in the fourth embodiment.

FIG. 16 is a flowchart showing a valid / invalid determination routine of over-aperture detection in the fifth embodiment.

FIG. 17 is a flowchart showing an over / aperture detection validity / invalidity determination routine in the sixth embodiment.

FIG. 18 is a flowchart showing an over / aperture detection validity / invalidity determination routine in a seventh embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Indoor unit, 2 ... Suction port, 3 ... Suction port, 4 ... Outlet port, 5 ... Ventilation path, 7 ... Auxiliary indoor heat exchanger, 8 ... Main indoor heat exchanger, 8a ... 1st heat exchanger, 8b … Second heat exchanger, 9
... Indoor fan, 11, 11 ... Vertical louver, 13, 1
4, 17 ... Heat exchanger temperature sensor, 15 ... Indoor temperature sensor, 16 ... Refrigerant temperature sensor, 18 ... Outside air temperature sensor, 2
1 ... Compressor, 22 ... Four-way valve, 23 ... Outdoor heat exchanger, 24
... electric expansion valve, 31 ... inverter circuit, 40 ... control unit.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Watanabe 336 Tatehara, Fuji City, Shizuoka Prefecture, Toshiba FEC Corporation (56) Reference JP-A-6-34184 (JP, A) JP-A-59 -122864 (JP, A) JP 62-258969 (JP, A) JP 6-317357 (JP, A) JP 6-281273 (JP, A) (58) Fields investigated (Int.Cl) . ⁷ , DB name) F25B 1/00 304 F25B 1/00 371

Claims (2)

(57) [Claims] 1. A refrigeration cycle in which a compressor, an outdoor heat exchanger, an electric expansion valve, and an indoor heat exchanger are sequentially connected, and an evaporation area provided in a target evaporation area and a target superheat area in the indoor heat exchanger during a dehumidification cycle. Equipped with a temperature sensor and an overheat zone temperature sensor, the detection temperature of the evaporation zone temperature sensor and the overheat zone temperature sensor
In an air conditioner that superheat-controls the opening of an electric expansion valve based on the difference from the detected temperature, a change in the detected temperature of the evaporation zone temperature sensor after the electric expansion valve is throttled by superheat control is detected, and this detection is performed.
If the temperature change increases, it is judged that the electric expansion valve is over-throttled.
Comprising a first over-aperture detection means for disconnection, when the first over aperture detecting means has detected an over aperture state, provided the first over aperture protection hand stage of opening the electric expansion valve by a predetermined opening degree An air conditioner characterized by that. 2. A refrigeration cycle in which a compressor, an outdoor heat exchanger, an electric expansion valve, and an indoor heat exchanger are sequentially connected, an indoor temperature sensor for detecting an indoor temperature, and target evaporation in the indoor heat exchanger during a dehumidification cycle. Equipped with an evaporation zone temperature sensor and an overheat zone temperature sensor provided in the target zone and the target superheat zone, and superheat control the opening of the electric expansion valve based on the difference between the temperature detected by the evaporation zone temperature sensor and the temperature detected by the overheat zone temperature sensor. In the air conditioner to detect the difference between the detection temperature of the evaporation zone temperature sensor and the detection temperature of the indoor temperature sensor after a predetermined time from the start of operation ,
When the difference is less than or equal to a predetermined value, the electric expansion valve is provided with second over-throttle detection means for judging that the throttle is over-throttled, and when the second over-throttle detection means detects an over-throttled state, the electric an air conditioner characterized in that a second over-squeeze protection hand stage of opening the expansion valve by a predetermined opening degree.