JPH06341719A - Operation controller for air conditioner - Google Patents

Abstract

PURPOSE:To realize a sufficient utilization of heat exchanging capacity by a method wherein an opening degree of an expansion valve is set large, when a sunction superheating degree is large, for example, when piping is long and outdoor temperature is high. CONSTITUTION:An opening degree controlling means 51 is provided to control an opening degree of an indoor electromotive expansion valve 32 so that a sunction superheating degree of refrigerant in an indoor heat exchanger 31 may reach a reference value. Further a capacity demanding means 52 is provided to output a demand signal which demands that an air conditioning capacity should be increased, when an indoor load becomes large. A superheating degree detecting means 53 is provided to output a superheating degree signal, when the temperature of a discharge pipe superheating degree of a compressor 21 becomes higher than a prescribed value, and a refrigerant shortage detecting means 54 is provided to output a gas shortage signal. A humidification controlling means 55 is provided to output a humidification permitting signal, when the demanding signal and the superheating degree signal are outputted and the gas shortage signal is not outputted, so that the opening degree controlling means 51 may be operated to lower the reference value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control device for an air conditioner, and more particularly to a measure for controlling an expansion valve.

[0002]

2. Description of the Related Art Conventionally, an air conditioner has been disclosed in Japanese Patent Laid-Open No.
As disclosed in JP-A-17358, a compressor, a four-way switching valve, an outdoor heat exchanger, an outdoor electric expansion valve, an indoor electric expansion valve, and an indoor heat exchanger are sequentially connected to form a main refrigerant circuit. Has been done. Further, during the cooling operation, the opening degree of the indoor electric expansion valve is PI-controlled (proportional / integral control) so that the superheat degree of the refrigerant in the indoor heat exchanger becomes a predetermined value. When the temperature is higher than 0 ° C., the opening degree of the indoor electric expansion valve is increased for a predetermined time to improve the energy effective rate (EER).

[0003]

However, in the above-described air conditioner, the opening degree of the indoor electric expansion valve is only open when the degree of superheat of the refrigerant in the indoor heat exchanger is large. Therefore, there is a problem that the capacity of the indoor heat exchanger cannot be fully exhibited and the energy effective rate (EER) is low. That is, it is not necessary to increase the degree of superheat when long piping is provided between the outdoor unit and the indoor unit or when the outdoor temperature is high. However, in the conventional air conditioner, since the opening degree of the indoor electric expansion valve is controlled only by the refrigerant state of the indoor heat exchanger, the opening degree cannot be set sufficiently large corresponding to the usage situation. There was a problem.

The present invention has been made in view of the above point, and the opening of the expansion valve is set to a large value even when the long piping or high ambient temperature is used, so that the heat exchanger capacity can be fully utilized. The purpose is to be able to.

[0005]

In order to achieve the above object, the means taken by the present invention is to increase the opening of the expansion valve when the load is large and the discharge pipe temperature of the compressor is large. It was done. Specifically, as shown in FIG. 1, the means taken by the invention according to claim 1 is as follows.
(21), heat source side heat exchanger (24), expansion valve with adjustable opening
The target is an operation control device of an air conditioner in which the closed side main refrigerant circuit (11) is formed by sequentially connecting the (32) and the utilization side heat exchanger (31). An opening control means (51) is provided to control the opening of the expansion valve (32) so that the heat exchange superheat of the refrigerant in the utilization side heat exchanger (31) reaches a predetermined target value. . Further, a capacity requesting means (52) for outputting a request signal for increasing the air conditioning capacity when the load on the usage side is increased based on the load on the usage side, the discharge temperature of the compressor (21) and the saturation temperature equivalent to the high pressure. And a superheat detecting means (53) for outputting a superheat signal when the superheat of the discharge pipe, which is the difference in temperature from the discharge pipe, exceeds a predetermined temperature. In addition, when the capacity request means (52) outputs a request signal and the superheat detection means (53) outputs a superheat signal, the opening control means (5
In 1), the wetness control means (55) for outputting the wetness permission signal to the opening degree control means (51) so as to reduce the target value of the heat exchange superheat degree is provided.

Further, the means taken by the invention according to claim 2 is the use side heat exchanger (31) in the invention according to claim 1 above.
While the refrigerant shortage detection means (54) for detecting the lack of refrigerant and outputting the gas shortage signal is provided, the wetness control means (55) is such that the refrigerant shortage detection means (54) is in a non-output state of the gas shortage signal. And a wetness permission signal can be output. The means taken by the invention according to claim 3 is the wetness control means in the invention according to claim 1 or 2 above.
(55) raises the third level signal for lowering the target value and the second level signal for maintaining the current state and the target value by the discharge pipe superheat degree based on the superheat degree signal output from the superheat degree detecting means (53) It is configured to output a wetness permission signal with the first level signal. Further, the means taken by the invention according to claim 4 is that in the invention according to claim 3, in the main refrigerant circuit (11), a liquid injection bypass passage (43) for guiding the liquid refrigerant to the suction side of the compressor (21). ) Is provided, while the injection control means (56) for controlling the opening and closing of the liquid injection bypass path (43), and the injection control means (56) outputs an opening signal of the liquid injection bypass path (43), wetness control Means (5
In 5), when the first level signal is output, level-up means (57) for outputting the level-up signal so as to output the second level signal instead of the first level signal is provided.

[0007]

With the above construction, in the invention according to claim 1,
First, during normal cooling operation, the opening control means (51)
Sets a target value of the heat exchange superheat degree in the use side heat exchanger (31), and controls the opening degree of the expansion valve (32) so as to reach this target value. In this normal control state, when the load on the utilization side becomes large, the capacity requesting means (52) outputs a request signal, and the discharge pipe temperature of the compressor (21) rises above the saturation temperature equivalent to the high pressure by a predetermined temperature. Superheat detection means (53)
Outputs a superheat signal. Then, the wetness control means (55) outputs the wetness permission signal in response to the request signal and the superheat degree signal. Particularly, in the invention according to claim 2, when the refrigerant shortage detection means (54) detects the refrigerant shortage and the refrigerant shortage detection means (54) does not output the gas shortage signal, the wetness control means (55) ) Will output a wetness permission signal.
The opening degree control means (51) receives the wetness permission signal, and the opening degree control means (51) lowers the target value of the heat exchange superheat degree. By reducing this target value, the expansion valve (32)
Will be opened more than in normal control.

Further, in the invention according to claim 3, the wetness control means (55) outputs a wetness permission signal having a level signal different depending on the superheat degree of the discharge pipe, and outputs a third level signal when the superheat degree of the discharge pipe is high. However, if the opening degree of the expansion valve (32) is increased and the superheat degree of the discharge pipe is not so high, a second level signal is output to maintain the opening degree of the expansion valve as it is, and if the superheat degree of the discharge pipe is low, 1
A level signal is output to reduce the opening of the expansion valve (32).
Further, in the invention according to claim 4, when the discharge pipe temperature T4 rises during the control of the expansion valve (32), the injection control means (56) opens the liquid injection bypass passage (43) to perform liquid injection. On the other hand, the level-up means (57) outputs a level-up signal, and the wetness control means (55) outputs a second level signal instead of the first level signal when the first level signal is output. That is, since the discharge pipe temperature is high, the opening degree control means (51) maintains the current state without throttling the indoor electric expansion valve (32).

[0009]

Therefore, according to the invention of claim 1,
Load on the user side When the indoor load is large and the superheat of the discharge pipe is high, the expansion valve (32) is opened widely, so the opening of the expansion valve (32) should be kept open when long piping or high outside air temperature is used. Therefore, it is possible to set the opening sufficiently large in accordance with the usage situation. As a result, the use side heat exchanger (31)
The energy effective rate (EER) can be improved because the above-mentioned ability can be fully exerted. Further, according to the invention of claim 2, since the expansion valve (32) is not opened at the time of outputting the gas shortage signal, the uneven flow of the refrigerant in the case of having a plurality of utilization side heat exchangers (31) is ensured. Can be prevented. Further, according to the invention of claim 3, since the opening degree of the expansion valve (32) is changed based on the degree of superheat of the discharge pipe, the air conditioning operation can be performed at the optimum discharge pipe temperature, and the compressor ( 21) can be operated in the optimum condition. Further, according to the invention of claim 4, since the expansion valve (32) is not throttled in the state where the liquid injection is being performed, the liquid injection can be ended early, and the input of the compressor (21) can be performed. Up can be suppressed.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 is an air conditioner according to the present invention.
The refrigerant piping system of the outdoor unit (2) and the indoor unit (3) in (1) is shown. The outdoor unit (2) includes a compressor (21) whose capacity is adjusted by an inverter (2a) whose output frequency is variably switched every 4 to 10 Hz within a range of 30 to 116 Hz, and a compressor (21). An oil separator (22) that separates the oil in the discharged gas, a four-way switching valve (23) that switches as shown by the solid line in the figure during cooling operation and switches as shown by the broken line in the figure during heating operation, and during cooling operation. An outdoor fan (2F) attached to the condenser, the outdoor heat exchanger (24) and the outdoor heat exchanger (24) as a heat source side heat exchanger that serves as an evaporator during heating operation,
Outdoor electric expansion valve (25) that throttles the refrigerant during heating operation
, A receiver (26) for storing the liquefied refrigerant, and an accumulator (27) are built-in as main equipment, and each equipment such as the compressor (21) and the outdoor heat exchanger (24) is a refrigerant pipe. (4) is connected so that the refrigerant can flow. Also,
The indoor unit (3) includes an indoor heat exchanger (31) as a utilization side heat exchanger that functions as an evaporator during cooling operation and a condenser during heating operation, and an indoor fan attached to the indoor heat exchanger (31). (3F), on the liquid pipe side of the refrigerant pipe (4) connected to the indoor heat exchanger (31), the indoor electric that adjusts the refrigerant flow rate during heating operation and throttles the refrigerant during cooling operation. Expansion valve
(32) is provided. And the outdoor unit (2)
And the indoor unit (3) is a connecting pipe that is the refrigerant pipe (4).
(41), the above compressor (21), outdoor heat exchanger
Each device such as (24) and indoor heat exchanger (31) is connected to the closed circuit by refrigerant pipe (4), and the heat obtained by heat exchange with outdoor air is released to the indoor air. A refrigerant circuit (11) is configured.

Further, (42) is a bypass path for heating overload control that bypasses the outdoor heat exchanger (24), and the bypass path (42) is common to the outdoor heat exchanger (24). Auxiliary heat exchanger (4a) installed in the air passage and capillary tube (4b)
And the auxiliary opening / closing valve (4c) which is opened when the refrigerant has a high pressure are sequentially connected in series and in parallel to the outdoor heat exchanger (24). Then, the heating overload control bypass path (42)
The auxiliary on-off valve (4c) is turned on to open when the high pressure is excessively increased during the cooling operation and during the heating operation, and a part of the discharged gas is used for heating overload control from the main refrigerant circuit (11). The bypass passage (42) is bypassed so that part of the discharged gas is condensed by the auxiliary heat exchanger (4a). (43) is a liquid injection bypass passage for injecting a liquid refrigerant into the suction side of the compressor (21) during heating / cooling operation to adjust the degree of superheat of the suction gas, which is the discharge pipe temperature of the compressor (21). An injection valve (4d) that is opened when it rises excessively and a capillary tube (4e) are interposed. (44) is an oil return pipe for returning the lubricating oil from the oil separator (22) to the compressor (21) through the capillary tube (4f). (45) is a compressor (21)
This is a pressure equalizing hot gas bypass that connects the discharge-side refrigerant pipe (4) and the suction-side refrigerant pipe (4) of the compressor (21) due to a thermo-off state, etc., and only for a certain period of time before restarting. A pressure equalizing valve (4g) and a capillary tube (4h) which are opened are provided. (46) is a pressure equalizing passage connected between the receiver (26) and the pressure equalizing hot gas bypass passage (45), one end of which is on the upper end surface of the receiver (26) and the other end of which is equalizing the above. It is connected to the upstream side of the pressure equalizing valve (4g) in the pressure hot gas bypass passage (45). The pressure equalizing passage (46) is provided with a check valve (4i) which allows only the refrigerant to flow from the receiver (26) to the pressure equalizing hot gas bypass passage (45), and the pressure equalizing valve (4g) is opened. In this state, the gas refrigerant in the upper layer of the receiver (26) can be introduced into the pressure equalizing hot gas bypass passage (45), that is, the suction side of the compressor (21) without introducing the liquid refrigerant. There is. Also,
(2b) is a suction refrigerant and a refrigerant pipe (4) on the suction side of the compressor (21).
This is a suction pipe heat exchanger for cooling the suction refrigerant by heat exchange with the liquid refrigerant in the liquid pipe to compensate for an increase in the degree of superheat of the refrigerant in the communication pipe (41).

Further, the air conditioner (1) is provided with many sensors, and (Th1) is a room temperature sensor for detecting an indoor temperature T1 which is the temperature of the intake air in the room, (Th2) and (Th3) is the liquid refrigerant temperature T2 and the gas refrigerant temperature in the liquid side and gas side refrigerant pipes (4) of the indoor heat exchanger (31), respectively.
Indoor liquid temperature sensor and indoor gas temperature sensor that detect T3, (T
h4) is a discharge pipe sensor that detects the discharge pipe temperature T4 of the compressor (21), (Th5) is an outdoor liquid temperature sensor that detects defrost etc. from the liquid refrigerant temperature T5 of the outdoor heat exchanger (24), Th6) is a suction pipe sensor that is arranged in the suction refrigerant pipe (4) on the downstream side of the suction pipe heat exchanger (2b) and detects the suction pipe temperature T6 of the compressor (21), and (Th7) is an outdoor The outside air temperature sensor (P1), which is arranged at the air inlet of the heat exchanger (24) and detects the outside air temperature T7 which is the temperature of the intake air outside the room, (P1) is arranged on the discharge side of the compressor (21). A high pressure sensor for detecting the high pressure side pressure of the refrigerant circuit (11),
(P2) is arranged on the suction side of the compressor (21) and is connected to the main refrigerant circuit (1
The low-pressure sensor (HPS) for detecting the low-pressure side pressure of 1) is a high-pressure pressure switch for protecting the compressor (21) arranged on the discharge side of the compressor (21). The electric expansion valves (25, 32) and the sensors (Th1 to Th7) are connected to the control unit (5) by a signal line, and the control unit (5) is connected to the sensors (Th1 to Th7). Each electric expansion valve (2
5, 32) etc. open / close control and capacity control of the compressor (21) are performed.

Further, the control unit (15) includes an opening control means (51), a capacity requesting means (52), a superheat degree detecting means (53), and a refrigerant shortage detecting means (54), which are features of the present invention. Wetness control means (55), injection control means (56), and level up means (57) are provided. The opening control means (51) is for the indoor liquid temperature sensor (Th2) during the cooling operation.
Based on the liquid refrigerant temperature T2 detected by the indoor gas temperature sensor (Th3) and the gas refrigerant temperature T3 detected by the indoor gas temperature sensor (Th3), the heat exchange superheat degree (hereinafter referred to as suction superheat degree) of the refrigerant in the indoor heat exchanger (31) is predetermined. The opening degree of the indoor electric expansion valve (32) is PI-controlled (proportional / integral control) so that the target value SHmin (for example, 5 ° C.) of Also, the ability requesting means (52)
Is configured to output a request signal for increasing the air conditioning capacity when the indoor load increases based on the indoor load (use side load). Specifically, the capability requesting means (5
2) is configured to output a request signal when the room temperature T1 detected by the room temperature sensor (Th1) becomes 5 ° C. or higher than the set temperature set by a remote controller or the like. The superheat detection means (53) is a compressor (21) detected by the discharge pipe sensor (Th4).
When the discharge pipe superheat DSH, which is the temperature difference between the discharge pipe temperature T4 and the saturation temperature Tc corresponding to the high-pressure pressure based on the high-pressure side pressure detected by the high-pressure sensor (P1), exceeds the specified temperature, a superheat signal is output. In other words, the temperature difference (T4-Tc) at which the discharge pipe temperature T4 rises above the saturation temperature Tc equivalent to the high pressure is calculated as the discharge pipe superheat degree DSH, and this discharge pipe superheat degree DSH is, for example, 20 ° C. When exceeded, it is configured to output a superheat signal. The refrigerant shortage detection means (54) is configured to detect the lack of refrigerant in the indoor heat exchanger (31) and output a gas shortage signal, that is, for example, a plurality of indoor units.
(3,3, ...), the indoor electric expansion valve (32) in the indoor unit (3) of 1 has been fully opened for 10 minutes, and the degree of superheat of the refrigerant in the indoor heat exchanger (31) Exceeds a predetermined value, for example, (indoor temperature T1−liquid-side refrigerant temperature T2-2.5) / 2, a gas shortage signal is output because gas shortage due to uneven flow occurs.

The wetness control means (55) is provided with the capacity requesting means (5
When the 2) outputs the request signal, the superheat detection means (53) outputs the superheat signal, and the refrigerant shortage detection means (54) is in the non-output state of the gas shortage signal, the opening control means (51) is configured to output a wetness permission signal to the opening degree control means (51) so as to reduce the target value SHmin of the intake superheat degree. Specifically, as shown in Table 1, the outside-wetting control means (55) controls the discharge tube superheat degree DSH based on the superheat degree signal output from the superheat degree detecting means (53) and the change amount of the discharge pipe temperature T4. And a map configured to output three level signals based on the. And the third level signal is
It is a signal that lowers the target value SHmin of the intake superheat,
The second level signal is a signal for maintaining the target value SHmin of the intake superheat degree at present, and the first level signal is a signal for increasing the target value SHmin of the intake superheat degree.

[Table 1] For example, the wetness control means (55) has a discharge pipe superheat DSH of 55 ° C.
When the discharge pipe temperature T4 rises above 2 ° C, the third level signal is output to increase the opening degree of the indoor electric expansion valve (32), and the discharge pipe superheat degree DSH exceeds 45 ° C. If it is less than 55 ° C. and the rise of the discharge pipe temperature T4 is between −2 and + 2 ° C., the second level signal for maintaining the opening degree of the indoor electric expansion valve (32) at present is output. Further, the injection control means (56) is a liquid injection bypass passage.
(43) is controlled to open and close.When the discharge pipe temperature T4 rises above 105 ° C or the discharge pipe superheat DSH rises above 55 ° C, the injection valve (4d) is opened while the discharge pipe temperature T4 rises. Lower than 85 ° C and discharge pipe superheat DSH is 35
It is configured to close the injection valve (4d) when the temperature becomes below ℃. The level-up means (57) is
When the injection control means (56) outputs a signal for opening the liquid injection bypass passage (43), the wetness control means (55) outputs a second level signal instead of the first level signal when outputting the first level signal. As shown by * in Table 1 above, the wetness control means (55) outputs the second level signal instead of the first level signal when performing liquid injection. It is designed to output.

Next, the operation of the air conditioner (1) will be described. In Fig. 2, during cooling operation of the air conditioner, the four-way switching valve (23) is switched to the solid line side in the figure, the auxiliary opening / closing valve (4c) of the auxiliary heat exchanger (4a) is always open, and the compressor is
The refrigerant compressed in (21) is condensed in the outdoor heat exchanger (24) and the auxiliary heat exchanger (4a), and is sent to the indoor unit (3) via the communication pipe (41). Then, in this indoor unit (3), the liquid refrigerant is decompressed by the indoor electric expansion valves (32) (32) and evaporated in the indoor heat exchanger (31), and then the outdoor unit (via the connecting pipe (41). It returns to 2) in a gas state and circulates so as to be sucked into the compressor (21). That is, the liquid refrigerant is the indoor heat exchanger (31)
In, the room air is cooled by exchanging heat with the room air and evaporating. Further, during the heating operation, the four-way switching valve (23) is switched to the side of the broken line in the figure, the flow of the refrigerant is opposite to that during the cooling operation, and the refrigerant compressed by the compressor (21) becomes the indoor heat. After being condensed in the exchanger (31), flowing to the outdoor unit (2) in a liquid state, decompressed by the outdoor electric expansion valve (25), and evaporated in the outdoor heat exchanger (24), the compressor (21)
Circulate back to. That is, the gas refrigerant heats the indoor air by exchanging heat with the indoor air in the indoor heat exchanger (31) and condensing. Therefore,
The opening control of the indoor electric expansion valve (32) during the cooling operation of the air conditioner (1) will be described with reference to FIG. First, the cooling operation is started, and in step ST1, the opening degree control means (51) sets the target value SHmin of the intake superheat degree, and the normal opening degree control is performed. That is, the opening control means
(51) shows that in normal control, the intake superheat becomes 5 ° C based on the liquid refrigerant temperature T2 detected by the indoor liquid temperature sensor (Th2) and the gas refrigerant temperature T3 detected by the indoor gas temperature sensor (Th3). Further, the opening degree of the indoor electric expansion valve (32) is PI controlled. While this normal control is being performed, the capacity requesting means (5
2) outputs the request signal, the superheat detection means (53) outputs the superheat signal, and the refrigerant shortage detection means (54) does not output the gas shortage signal.
Moving to ST2, the wetness control means (55) executes the wetness control of the indoor electric expansion valve (32). In other words, the room temperature T1 is higher than the set temperature by 5 ℃ or more, and the discharge pipe superheat degree DSH is 20 ℃.
When the gas shortage signal is not output in a state of exceeding the range, the wetness control is performed.

In this wetness control, first, step
After the timer is set in ST21, the process proceeds to step ST22, and the opening degree control means (51) sets the target value SHmin of the intake superheat degree. Since it is the time to enter the wetness control at present, 5 ° C. in step ST1 is set as it is. After that, when the timer times out, for example, when 10 minutes have elapsed, the process proceeds from step ST22 to step ST23, and the opening degree control means (51) is driven indoors based on the wetness permission signal output from the wetness control means (55). Set the target value SHmin of the expansion valve (32). That is, the wetness control means (55) takes in the discharge pipe temperature T4 at every sampling time of 2 minutes and displays the discharge pipe temperature T4 and the discharge pipe superheat degree DSH of the superheat degree detection means (53). The level signal is output from the map shown in FIG. For example, when the discharge pipe superheat degree DSH is 55 ° C. or higher and the rise of the discharge pipe temperature T4 is 2 ° C. or higher, the wetness control means (55)
Outputs a level signal and discharge pipe superheat DSH is 55 at 55 ° C or higher.
If it is lower than ℃ and the rise of the discharge pipe temperature T4 is between -2 and +2 ℃, the second level signal is output. And opening control means
When the third level signal is output, (51) lowers the intake superheat target value SHmin by 1 ° C and greatly controls the opening degree of the indoor electric expansion valve (32) to reduce the intake superheat. To do. Further, the opening degree control means (51) maintains the current target value SHmin of the intake superheat degree when the second level signal is output. When the first level signal is output, the opening control means (51) raises the target value SHmin of the intake superheat degree by 1 ° C. to increase the intake superheat degree, and the indoor electric expansion valve (32).
Control the opening degree of. In the current state, since it is the time when the wetness control is started, the third level signal is output,
The opening degree of the indoor electric expansion valve (32) is largely controlled.

After that, the above steps ST23 to ST
24, it is determined whether or not the target value SHmin is 5 ° C. Since it is now 1 ° C lower and 4 ° C, the determination becomes NO and the process moves to step ST25, where the target value SHmin is 1 ° C. Determine if it is ℃. If the target value SHmin is 4 ° C. as at present, the determination is NO and the above step ST21
Then, the above operation is repeated. That is, each level signal is output based on the discharge pipe temperature T4 and the discharge pipe superheat degree DSH, and the target value SHmin of the suction superheat degree is increased / decreased by 1 ° C. every 10 minutes, and the indoor electric expansion valve (32) is increased. Control the opening. While the indoor electric expansion valve (32) is being controlled, if the target value SHmin becomes 5 ° C, the step ST
If the determination in step 24 is YES, the process moves to step ST1 and returns to the normal control. Also, the indoor electric expansion valve (32)
When the discharge pipe temperature T4 rises to 105 ° C or higher or the discharge pipe superheat DSH becomes 55 ° C or higher during the control of, the injection control means (56) causes the injection valve (4d)
On the other hand, the level-up means (57) outputs a level-up signal, and the wetness control means (55) outputs a second level signal in place of the first level signal when the first level signal is output. That is, since the discharge pipe temperature T4 is high, the opening degree control means (51) maintains the current state without throttling the indoor electric expansion valve (32).

Thereafter, when the target value SHmin falls to 1 ° C. during the control of the indoor electric expansion valve (32), the determination in step ST25 is YES, the process proceeds to step ST26, and the timer is set. In step ST27, the opening degree control means (51) sets the target value SHmin of the intake superheat degree. In the first time, set 1 ° C in step ST23 as it is. After that, when the timer expires,
For example, when 2 minutes have elapsed, the process proceeds from step ST27 to step ST28, and the opening control means (51) sets the target value SHmin of the indoor electric expansion valve (32) based on the wetness permission signal output from the wetness control means (55). Set again. That is, the wetness control means (55) outputs a level signal based on the discharge pipe temperature T4 and the discharge pipe superheat degree DSH, as in step ST23. And
The opening control means (51), when the third level signal is output,
The target value SHmin is controlled by -2, and the target value SHmin is 1 ° C.
However, since the discharge pipe temperature T4 is high, the indoor electric expansion valve (32) is opened every 10 pulses by 10 pulses and the above step ST26 is performed.
Will return to. Further, when the second level signal is output, the opening control means (51) controls the target value SHmin to -1, maintains the current target value SHmin of the intake superheat degree, and returns to step ST26. It will be. The opening control means (5
In 1), when the first level signal is output, the target value SHmin is controlled to 0, and the discharge pipe temperature T4 has dropped, so the indoor electric expansion valve (32) is closed every 10 pulses for every 10 pulses. Step
Returning to ST26, the indoor electric expansion valve (32) is opened and closed every 10 pulses as described above. After that, when the cooling operation is stopped, when the discharge pipe superheat DSH rises above 20 ° C,
When the capacity requesting means (52) stops outputting the request signal, or when the refrigerant shortage detecting means (54) outputs the gas shortage signal, the process returns from step ST2 to step ST1 to control the opening degree. The means (51) will carry out normal control of the indoor electric expansion valve (32).

Therefore, according to this embodiment, when the indoor load is large and the discharge pipe superheat degree DSH is high, the indoor electric expansion valve
The opening of the indoor electric expansion valve (32) can be set to the maximum when the long piping or high outside temperature is used because the (32) is opened wide. Can be set large. As a result, the capacity of the indoor heat exchanger (31) can be fully exerted, so that the energy effective rate (EER) can be improved. Further, when the gas shortage signal is output, the indoor electric expansion valve (32) is not left open, so that it is possible to reliably prevent the nonuniform flow of the refrigerant in the case of having a plurality of indoor units (3, 3, ...). Further, since the opening degree of the indoor electric expansion valve (32) is changed based on the discharge pipe superheat degree DSH, the air conditioning operation can be performed at the optimum discharge pipe temperature T4, and the compressor (21) can be operated in the optimum state. You can drive. In addition, since the indoor electric expansion valve (32) is not throttled while liquid injection is being performed, the liquid injection can be ended early and the input increase of the compressor (21) can be suppressed.

In this embodiment, one indoor unit (3) is used.
Although the air conditioner (1) having the above has been described, it goes without saying that the present invention may be a multi-type having a plurality of indoor units (3, 3, ...). Also, opening control means
It goes without saying that (51) is not limited to the one that PI-controls the indoor electric expansion valve (32). Also, the wetness control means (55)
Has a map as shown in Table 1, but the map is not limited to this map, and the level signal is not limited to the type of the embodiment.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a refrigerant circuit diagram showing a refrigerant piping system of the air conditioner.

FIG. 3 is a control flow chart showing an opening control of an indoor electric expansion valve.

[Explanation of symbols]

 1 Air conditioner 11 Main refrigerant circuit 2 Outdoor unit 21 Compressor 24 Outdoor heat exchanger (heat source side heat exchanger) 25 Outdoor electric expansion valve 3 Indoor unit 31 Indoor heat exchanger (use side heat exchanger) 32 Indoor electric expansion Valve 43 Liquid injection bypass passage 4d Injection valve 5 Controller 51 Opening control means 52 Capacity demand means 53 Superheat detection means 54 Refrigerant shortage detection means 55 Wetness control means 56 Injection control means 57 Level up means

Claims (4)

[Claims] 1. A compressor (21), a heat source side heat exchanger (24),
An operation control device for an air conditioner in which an expansion valve with adjustable opening (32) and a heat exchanger (31) on the use side are connected in sequence to form a closed main refrigerant circuit (11). The opening side control means (51) for controlling the opening degree of the expansion valve (32) so that the heat exchange superheat degree of the refrigerant in the use side heat exchanger (31) reaches a predetermined target value, and the use side load Based on the above, the capacity requesting means for outputting a request signal for increasing the air conditioning capacity when the load on the use side increases
(52), superheat detection means (53) for outputting a superheat signal when the superheat degree of the discharge pipe based on the discharge temperature of the compressor (21) and the saturation temperature equivalent to the high pressure exceeds a predetermined temperature, and the above capacity. When the request means (52) outputs the request signal and the superheat detection means (53) outputs the superheat signal, the opening degree control means (51) becomes wet so as to reduce the target value of the heat exchange superheat. An operation control device for an air conditioner, comprising: a wetness control means (55) for outputting a permission signal to the opening degree control means (51). 2. The operation control device for an air conditioner according to claim 1, further comprising a refrigerant shortage detection means (54) for detecting a refrigerant shortage of the utilization side heat exchanger (31) and outputting a gas shortage signal. On the other hand, the wetness control means (55) is characterized in that when the refrigerant shortage detection means (54) is in a non-output state of a gas shortage signal, it is configured to be in a state in which a wetness permission signal can be output. Operation control device for the harmony device. 3. The operation control device for an air conditioner according to claim 1 or 2, wherein the wetness control means (55) is controlled by the superheat degree of the discharge pipe based on the superheat degree signal output from the superheat degree detecting means (53). An air conditioner configured to output a wetness permission signal including a third level signal for decreasing the value, a second level signal for maintaining the current state, and a first level signal for increasing the target value. Operation control device. 4. The operation control device for an air conditioner according to claim 3, wherein the main refrigerant circuit (11) is provided with a liquid injection bypass passage (43) for guiding the liquid refrigerant to the suction side of the compressor (21). Meanwhile, when the injection control means (56) for controlling the opening and closing of the liquid injection bypass passage (43) and the injection control means (56) output an open signal of the liquid injection bypass passage (43), the wetness control means (55) ) Is provided with a level-up means (57) for outputting a level-up signal so as to output a second level signal instead of the first level signal when the first level signal is output. Device operation control device.