JPH109683A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent a wet vapor suction to a compressor and to improve the life of the compressor by detecting the degree of superheat of refrigerant in a heat exchanger, and controlling to raise an operating frequency of the compressor by a predetermined value at the time when the degree of superheat is smaller than a target value by a predetermined value or more and the travel of a motor driven expansion valve is minimum. SOLUTION: In a cooling operation, an indoor temperature, a set indoor temperature, an indoor heat exchanger temperature and a suction side tube temperature are read. An operating frequency of a compressor 1 is controlled in response to a difference between the indoor temperature and the set indoor temperature, and a target value of the degree of superheat is set. The degree of superheat of refrigerant in the exchanger 5 is calculated from a difference between the suction side tube temperature and the exchanger temperature. A necessary amount of a valve opening operating to an opening of a motor driven expansion valve 4 at present time point in response to a difference between the set target value and the degree of superheat is obtained, and the valve 4 is operated to travel. In this case, when the degree is smaller by a predetermined value or more than the target value and the opening of the valve 4 is minimum, the operating frequency of the compressor is controlled to be raised by a predetermined value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for controlling a degree of superheat using an electric expansion valve.

[0002]

2. Description of the Related Art An air conditioner is equipped with a refrigeration cycle in which a compressor, an outdoor heat exchanger, a decompressor, an indoor heat exchanger, and the like are sequentially connected. The operation of the compressor is controlled by comparison with a temperature (set room temperature) preset by a remote controller or the like.

For example, a difference (= air-conditioning load) between the detected indoor temperature and the set indoor temperature is obtained, and the operating frequency of the compressor is controlled in such a direction that the temperature difference becomes zero. By this control, an optimal cooling capacity or heating capacity corresponding to the air conditioning load is exhibited.

Simultaneously with the operation frequency control, the degree of superheat (also referred to as superheat amount) of the refrigerant in the outdoor heat exchanger (during cooling) or the indoor heat exchanger (during heating) functioning as an evaporator is detected. Is the target value.
The degree of opening of the electric expansion valve, which is a pressure reducer, is controlled.
The degree of opening of the electric expansion valve continuously changes in accordance with the number of supplied drive pulses.

[0005] However, when the degree of superheat is smaller than the target value, the temperature difference between the outside air and the refrigerant is small, and it is likely that all the refrigerant flowing from the electric expansion valve to the evaporator cannot be completely evaporated. Then, a so-called liquid back occurs in which the liquid refrigerant that has not completely evaporated is sucked into the compressor, which may cause damage to the compressor. Therefore, in this case, the opening of the electric expansion valve is reduced. As a result, the pressure of the refrigerant flowing to the evaporator after passing through the electric expansion valve is reduced, whereby the liquid refrigerant is easily vaporized and liquid back to the compressor is prevented.

On the other hand, if the degree of superheat is larger than the target value, the temperature difference between the outside air and the refrigerant is too large, and the refrigerant flowing from the electric expansion valve to the evaporator absorbs too much heat, and the indoor temperature Adversely affect Therefore, in this case, the opening degree of the electric expansion valve is increased, the pressure of the refrigerant flowing from the electric expansion valve to the evaporator is increased, and the absorption of heat from the outside air is suppressed.

When the superheat reaches the target value, the opening of the electric expansion valve at that time is maintained as it is. As shown in the flowchart of FIG. 9, the difference Tk (= Ta−Tx) between the detected room temperature Ta and the set room temperature Tx is used not only for controlling the operation frequency but also for controlling the valve opening degree. There is something to do.

In this control, during cooling, the outside air temperature To
When the temperature becomes equal to or higher than ℃, the minimum value of the operating frequency is increased by a predetermined value from the normal value. That is, the outside air temperature To
Is high and the heat radiation effect of the outdoor heat exchanger (condenser) is reduced, the indoor heat exchanger temperature (evaporator temperature) T
The lowering of the operating frequency is limited so that e can be lowered to obtain a sufficient cooling effect.

During heating, the outside air temperature To is lower than -1 ° C., and the indoor heat exchanger temperature (condenser temperature) Te is 18 ° C.
In a situation where the indoor heat exchanger temperature Te is higher (ie, the set indoor temperature Tx is higher), the lowering of the operating frequency is limited so that a state in which the indoor heat exchanger temperature Te is higher than 18 ° C. and sufficient heating capacity can be obtained.

It is determined whether or not the operating frequency of the compressor is in a low frequency range. If the determination is not satisfied, a normal B is maintained as a control value holding time of the operating frequency.
If the determination is satisfied, A (> B) longer than usual is secured as the control value holding time. By securing a long control value holding time A in the low frequency region, frequent repetition of the ON / OFF operation of the compressor is avoided, and the indoor temperature is stabilized.

[0011]

When the degree of superheat is smaller than the target value, the opening of the electric expansion valve is reduced to prevent the liquid from flowing back to the compressor. If it is already in the minimum state, it is impossible to further reduce the opening, and eventually it may not be possible to prevent the liquid back.

The present invention has been made in view of the above circumstances,
It is an object of the air conditioners of the first, third, and fourth inventions to reliably prevent liquid back to the compressor and to improve the life of the compressor. It is an object of the air conditioner of the second invention to prevent liquid back to the compressor as much as possible and to improve the life of the compressor.

[0013]

An air conditioner according to a first aspect of the present invention includes a refrigeration cycle in which a compressor, an outdoor heat exchanger, an electric expansion valve, and an indoor heat exchanger are connected. Controls the operating frequency of the heat exchanger, detects the degree of superheat of the refrigerant in the outdoor heat exchanger or the indoor heat exchanger that functions as an evaporator, and controls the opening of the electric expansion valve so that the degree of superheat becomes a target value. A control means for increasing the operating frequency of the compressor by a predetermined value when the degree of superheat is smaller than the target value by a predetermined value or more and the opening of the electric expansion valve is minimum.

An air conditioner according to a second aspect of the present invention includes a refrigeration cycle connecting a compressor, an outdoor heat exchanger, an electric expansion valve, and an indoor heat exchanger, and controls an operating frequency of the compressor according to an air conditioning load. And detecting the degree of superheat of the refrigerant in the outdoor heat exchanger or the indoor heat exchanger functioning as an evaporator, and controlling the degree of opening of the electric expansion valve so that the degree of superheat becomes a target value. When the degree of superheat is smaller than the target value by a predetermined value or more, and when the opening of the electric expansion valve is at a minimum, control means is provided for extending the control value holding time of the operating frequency of the compressor.

An air conditioner according to a third aspect of the present invention includes a refrigeration cycle in which a compressor, an outdoor heat exchanger, an electric expansion valve, and an indoor heat exchanger are connected, and controls an operating frequency of the compressor according to an air conditioning load. And detecting the degree of superheat of the refrigerant in the outdoor heat exchanger or the indoor heat exchanger functioning as an evaporator, and controlling the degree of opening of the electric expansion valve so that the degree of superheat becomes a target value. When the degree of superheat is smaller than the target value by a predetermined value or more and the opening degree of the electric expansion valve is the minimum, the operation frequency of the compressor is increased by a predetermined value, and the control value holding time of the operation frequency is extended. Means. In an air conditioner according to a fourth aspect, the control means according to the first or third aspect increases the operating frequency of the compressor by a predetermined value every predetermined time.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 2, an outdoor heat exchanger 3 is connected to the discharge port of the compressor 1 via a four-way valve 2. An indoor heat exchanger 5 is connected to the outdoor heat exchanger 3 via a motor-operated expansion valve 4 which is a decompressor, and the indoor heat exchanger 5 is connected to the suction port of the compressor 1 via the four-way valve 2. Is connected to the pipe.

The electric expansion valve 4, whose opening continuously changes in accordance with the number of supplied drive pulses, is called a pulse motor valve (PMV). During the cooling operation, the refrigerant flows in the direction of the solid line arrows in the drawing to form a cooling cycle, and the outdoor heat exchanger 3 functions as a condenser and the indoor heat exchanger 5 functions as an evaporator.

At the time of the heating operation, by switching the flow path of the four-way valve 2, the refrigerant flows in the direction of the dashed arrow in the drawing to form a heating cycle, the indoor heat exchanger 5 is a condenser, and the outdoor heat exchanger 3 is an evaporator. Function as

An outdoor fan 6 is provided near the outdoor heat exchanger 3. The outdoor fan 6 forces outdoor air to pass through the outdoor heat exchanger 3. An indoor fan 7 is provided near the indoor heat exchanger 5. The indoor fan 7 forces indoor air to pass through the indoor heat exchanger 5.

A suction pipe temperature sensor 8 is attached to a pipe connected to a suction port of the compressor 1. The suction side pipe temperature sensor 8 detects the suction side pipe temperature Ts. A heat exchanger temperature sensor 11 is attached to the outdoor heat exchanger 3. The heat exchanger temperature sensor 11 detects the temperature of the outdoor heat exchanger 3.

An outside air temperature sensor 12 is provided in a suction air passage to the outdoor fan 6. The outside air temperature sensor 12 detects the outside air temperature To. A heat exchanger temperature sensor 21 is attached to the indoor heat exchanger 5. Heat exchanger temperature sensor 21
Detects the temperature of the indoor heat exchanger 5.

An indoor temperature sensor 22 is provided in a suction air passage of the indoor fan 7. The indoor temperature sensor 22 detects the indoor temperature Ta. The control circuit is shown in FIG.

An indoor control unit 40 is connected to the commercial AC power supply 30. An outdoor controller 50 is connected to the indoor controller 40 via a power supply line 31 and a serial signal line 32. The serial signal line 32 is for performing data transfer synchronized with the power supply voltage.

The indoor controller 40 includes a heat exchanger temperature sensor 2
1, an indoor temperature sensor 22, a speed control circuit 41, a louver drive circuit 42, and a remote control type operation device (hereinafter, abbreviated as a remote control) 60 are connected.

The speed control circuit 41 controls the speed of the indoor fan motor 7.
Control the speed of M. The louver drive circuit 42 drives the louver motor 43. This louver motor 43 is
Although not shown, a louver for adjusting the angle of the wind blown into the room up and down (or left and right) is driven. The remote controller 60 is for setting various operating conditions.

The outdoor control unit 50 includes a four-way valve 2, an electric expansion valve (PMV) 4, a suction pipe temperature sensor 8, a heat exchanger temperature sensor 11, an outside air temperature sensor 12, and an inverter circuit 5.
1. The fan drive circuit 52 is connected.

The inverter circuit 51 rectifies the commercial AC power supply voltage, converts it into a voltage (and level) having a frequency (and level) according to a command from the outdoor control unit 50, and outputs the voltage. This output is the driving power of the compressor motor 1M. The fan drive circuit 52 drives the outdoor fan motor 6M.

The indoor control unit 40 and the outdoor control unit 50
Each is composed of a microcomputer and its peripheral circuits, and has the following [1] to [11] as main functional means.

[1] The flow path of the four-way valve 2 is maintained in a neutral state, and the refrigerant discharged from the compressor 1 is supplied to the four-way valve 2, the outdoor heat exchanger 3, the electric expansion valve 4, the indoor heat exchanger 5, and the four-way valve 2. Means for returning to the compressor 1 to perform a cooling operation.

[2] The flow path of the four-way valve 2 is switched, whereby the refrigerant discharged from the compressor 1 is passed through the four-way valve 2, the indoor heat exchanger 5, the electric expansion valve 4, the outdoor heat exchanger 3, and the four-way valve 2. Means for returning to the compressor 1 to perform a heating operation.

[3] A difference Tk (= air-conditioning load) between the room temperature Ta detected by the room temperature sensor 22 and a set room temperature Tx set in advance by the remote controller 60 is determined as an air-conditioning load, and according to the temperature difference Tk. Means for controlling the operating frequency F of the compressor 1 (the output frequency of the inverter circuit 51).

[4] Means for setting a target value SHx of the degree of superheat in accordance with the temperature difference Tk. [5] A means for holding the control value (that is, the operating frequency F) for a predetermined time t ₁ every time the operating frequency F is controlled.
It is called a control data holding time to a predetermined time t _1. By securing this control value holding time t ₁ , the compressor 1
In order to stabilize the indoor temperature by suppressing the frequent fluctuation of the capacity.

[0033] [6] operation frequency F is determined whether the low frequency range, if the determination is not satisfied to ensure normal value as the control value holding time t ₁ of the above, if the determination is satisfied the control means for securing a longer than normal as a value holding time t _1. By ensuring longer control value holding time t ₁ of the low-frequency range, to avoid repetition of frequent on-off operation of the compressor, so that stabilize the room temperature.

[7] During the cooling operation, the detected temperature Ts of the suction side pipe temperature sensor 8 and the detected temperature of the heat exchanger temperature sensor 21 (the temperature of the indoor heat exchanger 5 functioning as an evaporator) Te
Means for calculating the difference (= Ts−Te) as the degree of superheat SH of the refrigerant in the indoor heat exchanger 5.

[8] During the heating operation, the detected temperature Ts of the suction side pipe temperature sensor 8 and the detected temperature of the heat exchanger temperature sensor 11 (temperature of the outdoor heat exchanger 3 functioning as an evaporator) Tc.
(= Ts−Tc) as the degree of superheat SH of the refrigerant in the outdoor heat exchanger 3.

[9] The target value SHx and the superheat degree SH
Means for calculating a difference ΔT (= SHx−SH) from the above. [10] In order to bring the degree of superheat SH to the target value SHx, the required amount ΔQ of the opening operation of the electric expansion valve 4 with respect to the current opening Q is determined according to the above ΔT, and the electric expansion is performed by the required amount ΔQ. Means for operating the opening of the valve 4.

[11] When the ΔT is larger than the predetermined value H (ΔT> H), that is, when the superheat degree SH is separated from the target value SHx by the predetermined value H or more, the opening degree of the electric expansion valve 4 is increased. Means for judging whether or not the state is at a minimum, and if not minimum, the opening degree of the electric expansion valve 4 is decreased by a predetermined value; if it is at a minimum, the operating frequency F is increased by a predetermined value every predetermined time. This aims at preventing liquid back to the compressor 1.

Next, the operation of the above configuration will be described with reference to FIGS. During operation (YES in step 101)
), Various temperature data (room temperature Ta, set room temperature T)
x, the indoor heat exchanger temperature Te, the suction side pipe temperature Ts, the outside air temperature To, and the outdoor heat exchanger temperature Tc) are read (step 102).

If the operation is the cooling operation (YES in step 103)
), A difference Tk (= Ta−Tx) between the room temperature Ta detected by the room temperature sensor 22 and the set room temperature Tx preset by the remote controller 60 is calculated (step 104).
Then, the operating frequency F of the compressor 1 is controlled according to the temperature difference Tk, and the target value SHx of the degree of superheat is set according to the temperature difference Tk (step 105).

The temperature Ts (corresponding to the temperature of the refrigerant flowing out of the indoor heat exchanger 5 functioning as an evaporator) of the suction pipe of the compressor 1 is detected by the suction pipe temperature sensor 8.
The difference (= Ts−T) between the detected temperature Ts and the detected temperature of the heat exchanger temperature sensor 21 (the temperature of the indoor heat exchanger 5) Te.
e) is calculated as the degree of superheat SH of the refrigerant in the indoor heat exchanger 5. Then, a difference ΔT (= SHx−SH) between the set target value SHx and the degree of superheat SH is calculated,
According to the ΔT, the required amount ΔQ of the opening operation of the electric expansion valve 4 with respect to the current opening Q is obtained. This required amount Δ
Q, the opening Q of the electric expansion valve 4 is operated (step
106). By this opening degree operation, the degree of superheat SH becomes the target value SH.
Move to x.

FIG. 5 shows a Mollier diagram during the cooling. In the case of the heating operation (NO in step 103), the difference Tk (= Tx) between the set room temperature Tx preset by the remote controller 60 and the room temperature Ta detected by the room temperature sensor 22
−Ta) is calculated (step 107). Then, the operating frequency F of the compressor 1 is controlled according to the temperature difference Tk, and the target value SHx of the degree of superheat is set according to the temperature difference Tk (step 108).

The temperature Ts (corresponding to the temperature of the refrigerant flowing out of the outdoor heat exchanger 3 functioning as an evaporator) of the suction side pipe of the compressor 1 is detected by the suction side pipe temperature sensor 8.
The difference (= Ts−T) between the detected temperature Ts and the detected temperature of the heat exchanger temperature sensor 11 (the temperature of the outdoor heat exchanger 3) Tc.
c) is calculated as the degree of superheat SH of the refrigerant in the outdoor heat exchanger 3. Then, a difference ΔT (= SHx−SH) between the set target value SHx and the degree of superheat SH is calculated,
According to the ΔT, the required amount ΔQ of the opening operation of the electric expansion valve 4 with respect to the current opening Q is obtained. This required amount Δ
Q, the opening Q of the electric expansion valve 4 is operated (step
109). By this opening degree operation, the superheat degree SH becomes the target value SH
Move to x.

FIG. 6 shows a Mollier chart during this heating. In this way, the timer operation is started with the operation frequency F being controlled and the opening degree Q of the electric expansion valve 4 being operated (step 110). The timer operation is used to count the control value holding time t ₁ of the operation frequency F.

When the control value holding time t ₁ has elapsed (YES in step 111), it is determined whether ΔT is greater than a predetermined value H (step 112). When ΔT is larger than a predetermined value H (ΔT> H, YES in step 112), that is, when the superheat degree SH is smaller than the target value SHx by a predetermined value H or more, the opening degree Q of the electric expansion valve 4 is minimized. Is determined (step 113).

As shown in FIG. 3, the minimum value of the opening degree Q is, as shown in FIG. Two levels of reference opening are set, each larger by 10 and 5 pulses as the number of pulses.

If the opening Q has decreased to the X region smaller than the first reference opening (Qmin + 5 pulse opening), it is determined that the opening Q is in the minimum state. Thereafter, the opening degree Q is larger than the second reference opening degree (Qmin + opening amount for 10 pulses).
By increasing to the region, it is determined that the opening degree Q has departed from the minimum state.

As a minimum value of the opening degree Q, it is needless to say that the actual minimum value Qmin which cannot be reduced by the valve mechanism may be directly applied. If the opening Q of the electric expansion valve 4 is not the minimum (NO in step 113), the opening Q of the electric expansion valve 4 is reduced by a predetermined value (step 114).
). Thus, the amount of the refrigerant flowing from the electric expansion valve 4 to the indoor heat exchanger 5 is reduced by reducing the valve opening degree,
All of the refrigerant flowing into the indoor heat exchanger 5 evaporates. Therefore, liquid back to the compressor 1 is prevented.

If the opening Q of the electric expansion valve 4 is already in the minimum state (YES in step 113), it is impossible to further restrict the opening, so that the operating frequency F is kept at the predetermined value (for example, 30 seconds). ) Is increased by a predetermined value (for example, 5 Hz) (step 115). By increasing the operating frequency F in this manner, not only the indoor heat exchanger 5 but also the area from the indoor heat exchanger 5 to the suction pipe becomes a superheated region of the refrigerant. As a result, liquid back to the compressor 1 is reliably prevented, and the life of the compressor 1 can be improved.

When an operation stop command is input from the remote controller 60 (YES in step 116), the operation ends. Next, the second
An example will be described.

The second embodiment differs from the first embodiment only in [11] among [1] to [11], which are the main functional units of the indoor control unit 40 and the outdoor control unit 50, as follows. [11] When ΔT is larger than the predetermined value H (ΔT> H), that is, when the superheat degree SH is smaller than the target value SHx, the predetermined value H
When it is more than the distance, it is determined whether the opening degree of the electric expansion valve 4 is in the minimum state. If not, the opening degree of the electric expansion valve 4 is reduced by a predetermined value. means for extending the control value holding time t _1.

The other structure is the same as that of the first embodiment. The operation is shown in the flowchart of FIG. 7 (up to step 112 is the same as in FIG. 4).

If the opening Q of the electric expansion valve 4 is not the minimum (NO in step 113), the opening Q of the electric expansion valve 4 is reduced by a predetermined value (step 114). However, if the opening degree Q of the electric expansion valve 4 is already in the minimum state (step 113).
YES), since it is impossible to reduce the opening further, the control value holding time t _{1 of} the operating frequency F is set to the predetermined time t ₂
It is extended (step 117).

If the control value holding time t _{1 of the} operating frequency F becomes long, for example, even if the load becomes low and the compressor 1 is turned off, the operation is not immediately turned off. Will be continued as much as possible. As a result, the original liquid-back preventing action due to the decrease in the opening degree Q of the electric expansion valve 4 is continued as much as possible.

Next, a third embodiment will be described. Third
In the embodiment, among [1] to [11], which are main functional units of the indoor control unit 40 and the outdoor control unit 50, only [11] is different from the first and second embodiments as follows.

[11] When ΔT is greater than a predetermined value H (Δ
T> H), that is, when the superheat degree SH is smaller than the target value SHx by a predetermined value H or more, it is determined whether the opening degree of the electric expansion valve 4 is in the minimum state. Means for reducing the opening of the valve 4 by a predetermined value, and if it is the minimum, increasing the operating frequency F by a predetermined value every predetermined time and extending the control value holding time t ₁ of the operating frequency F.

The other structure is the same as that of the first embodiment. The operation is shown in the flowchart of FIG. 8 (up to step 112 is the same as in FIG. 4).

If the opening Q of the electric expansion valve 4 is not the minimum (NO in step 113), the opening Q of the electric expansion valve 4 is reduced by a predetermined value (step 114). However, if the opening degree Q of the electric expansion valve 4 is already in the minimum state (step 113).
YES), since it is impossible to reduce the opening further, the operating frequency F is increased by a predetermined value (for example, 5 Hz) every predetermined time (for example, 30 seconds) (step 115), and the operating frequency F control data holding time t ₁ of the predetermined time t ₂ extension (step 117).

As the operating frequency F is increased in this way, the amount of refrigerant that the compressor 1 draws from the evaporator (the indoor heat exchanger 5 during cooling and the outdoor heat exchanger 3 during heating) increases. The pressure in the evaporator drops. As a result, it is possible to further reduce the pressure from a state in which the opening degree of the electric expansion valve 4 is minimized and the pressure in the evaporator is reduced, and the liquid refrigerant is easily vaporized. Is reliably prevented.

Moreover, the control value holding time t of the operating frequency F
_As a result of the extension of ₁ , for example, even if the load becomes low and the compressor 1 is turned off, the operation is not turned off immediately and the operation of the compressor 1 is continued as much as possible. As a result, the operation of preventing the liquid back caused by increasing the operating frequency F is continued as much as possible. The present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention.

[0060]

As described above, in the air conditioner of the first invention, when the degree of superheat is smaller than the target value by a predetermined value or more and the opening of the electric expansion valve is minimum, the operating frequency of the compressor is reduced. Since the configuration is such that the predetermined value is increased, liquid back to the compressor is reliably prevented, and the life of the compressor can be improved.

An air conditioner according to a second aspect of the present invention is configured such that when the degree of superheat is smaller than a target value by a predetermined value or more and the opening of the electric expansion valve is minimum, the control value holding time of the operating frequency of the compressor is extended. Therefore, liquid back to the compressor can be prevented as much as possible to improve the life of the compressor.

In the air conditioner according to the third aspect of the present invention, when the degree of superheat is smaller than the target value by a predetermined value or more and the opening of the electric expansion valve is minimum, the operating frequency of the compressor is raised by a predetermined value, and the operation of the compressor is increased. Since the control value holding time of the frequency is extended, liquid back to the compressor is reliably prevented, and the life of the compressor can be improved.

In the air conditioner of the fourth invention, the control means of the first or third invention is configured to increase the operating frequency of the compressor by a predetermined value at predetermined time intervals. And the life of the compressor can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control circuit of each embodiment.

FIG. 2 is a configuration diagram of a refrigeration cycle of each embodiment.

FIG. 3 is a diagram showing conditions for determining a minimum value of a valve opening in each embodiment.

FIG. 4 is a flowchart for explaining the operation of the first embodiment.

FIG. 5 is a Mollier chart during cooling in each embodiment.

FIG. 6 is a Mollier chart during heating in each embodiment.

FIG. 7 is a flowchart for explaining the operation of the second embodiment.

FIG. 8 is a flowchart for explaining the operation of the third embodiment.

FIG. 9 is a flowchart showing a control example of a conventional air conditioner.

[Explanation of symbols]

1 ... Compressor, 3 ... Outdoor heat exchanger, 4 ... Electric expansion valve, 5 ...
Indoor heat exchanger, 6 ... Outdoor fan, 7 ... Indoor fan, 8 ...
Suction side pipe temperature sensor, 11 ... heat exchanger temperature sensor, 1
2: indoor temperature sensor, 21: heat exchanger temperature sensor, 22
... outdoor temperature sensor, 40 ... indoor control unit, 50 ... outdoor control unit.

Claims (4)

[Claims] A refrigeration cycle connected to a compressor, an outdoor heat exchanger, an electric expansion valve, and an indoor heat exchanger, and controls an operating frequency of the compressor according to an air conditioning load;
In an air conditioner that detects the degree of superheat of a refrigerant in an outdoor heat exchanger or an indoor heat exchanger that functions as an evaporator and controls the degree of opening of an electric expansion valve so that the degree of superheat becomes a target value, the degree of superheat is An air conditioner comprising: control means for increasing an operating frequency of the compressor by a predetermined value when the opening degree of the electric expansion valve is smaller than the target value by a predetermined value or more. 2. A refrigeration cycle including a compressor, an outdoor heat exchanger, an electric expansion valve, and an indoor heat exchanger, wherein the operating frequency of the compressor is controlled according to an air conditioning load.
In an air conditioner that detects the degree of superheat of a refrigerant in an outdoor heat exchanger or an indoor heat exchanger that functions as an evaporator and controls the degree of opening of an electric expansion valve so that the degree of superheat becomes a target value, the degree of superheat is An air conditioner, comprising: a control unit for extending a control value holding time of an operating frequency of the compressor when the opening degree of the electric expansion valve is smaller than the target value by a predetermined value or more. . 3. A refrigeration cycle including a compressor, an outdoor heat exchanger, an electric expansion valve, and an indoor heat exchanger connected to control an operation frequency of the compressor according to an air conditioning load.
In an air conditioner that detects the degree of superheat of a refrigerant in an outdoor heat exchanger or an indoor heat exchanger that functions as an evaporator and controls the degree of opening of an electric expansion valve so that the degree of superheat becomes a target value, the degree of superheat is Control means for increasing the operating frequency of the compressor by a predetermined value and extending the control value holding time of the operating frequency when the opening degree of the electric expansion valve is smaller than the target value by a predetermined value or more and the opening degree of the electric expansion valve is a minimum. An air conditioner characterized by being provided. 4. The air conditioner according to claim 1, wherein the control means increases the operating frequency of the compressor by a predetermined value at predetermined time intervals.