JPH06341695A - Operation control device for air conditioner - Google Patents

Abstract

PURPOSE:To enable a rapid transferring of a normal control to be attained while a specified flow rate of refrigerant is assured, and utilize fully a capacity of a heat exchanger. CONSTITUTION:There is provided a liquid temperature outputting means 52 for comparing a calculated liquid refrigerant temperature with a detected liquid refrigerant temperature based on a saturation temperature corresponding to a low pressure and outputting a lower temperature as a controlled liquid temperature. Additionally, there is provided a value-travel control means 53 for use in controlling a degree of opening of an indoor device side electrical expansion valve 32 during a cooling operation in such a manner that a degree of over-heating based on the controlled liquid temperature and the detected gas refrigerant temperature becomes a predetermined value. In addition, there is also provided a super cooling control means 55 for use in controlling a valve travel of the indoor device side electrical expansion valve 32 in such a manner that a degree of super cooling during a heating operation becomes a predetermined value. Further, there is provided a difference temperature judging means 56 for judging a difference temperature between a saturation temperature Tc corresponding to a high pressure and an indoor air temperature T1. Additionally, there is provided a valve- travel holding mans 57 for holding the indoor device side electrical expansion valve 32 during a heating operation to a predetermined degree of opening until the difference temperature discriminated by the difference temperature discriminating means 56 becomes a predetermined value or more.

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, Japanese Patent Publication No.
As disclosed in JP-A-49034, 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. When the air-conditioning operation is started, the initial value of each electric expansion valve is set to a pre-stored opening, and the initial opening is held for a predetermined time. The normal control is performed according to the cooling degree.

[0003]

However, in the operation control device of the air conditioner described above, the stored data of the initial opening of the electric expansion valve can be rewritten to the opening during stable operation. Since the predetermined time is fixed to a constant initial opening, there is a problem that it takes time to shift to the normal control. That is, during the cooling operation and the heating operation, the indoor electric expansion valve is held at the initial opening regardless of the degree of superheat, etc. until a predetermined time elapses. There was a problem that the ability could not be fully exerted. Also,
When the indoor electric expansion valve is superheat-controlled from the start-up during the cooling operation, the superheat is not generated at the start-up, so the indoor electric-expansion valve is controlled only in the closing direction. On the other hand, even in the heating operation, if the indoor electric expansion valve is supercooled from the start-up time, the operating frequency of the compressor becomes low due to the low pressure drooping at the time of start-up, the high-low differential pressure becomes small, and the refrigerant hardly flows, Moreover, there is a problem that the temperature of the liquid refrigerant in the indoor heat exchanger becomes almost equal to the indoor temperature, and the indoor electric expansion valve is throttled because the degree of supercooling is small.

The present invention has been made in view of the above circumstances, and ensures a constant refrigerant flow rate, speeds up the transition to normal control, and enables the heat exchanger capacity to be fully utilized. That is the purpose.

[0005]

In order to achieve the above object, the means taken by the present invention controls the opening degree of an expansion valve on the basis of the pressure equivalent saturation temperatures of the suction side and the discharge side of a compressor. It was done like this. 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). Further, a liquid temperature detection means (Th2) and a gas temperature detection means (Th3) for respectively detecting the suction side liquid refrigerant temperature and the outlet side gas refrigerant temperature in the utilization side heat exchanger (31) are provided, and the compression is performed. A saturation temperature detecting means (51) for detecting a saturation temperature corresponding to the low pressure on the suction side of the machine (21) is provided. Furthermore, the main refrigerant circuit (1
Liquid refrigerant temperature calculated by adding the predetermined temperature determined by the pressure loss based on the pipe length of 1) to the saturation temperature equivalent to the low pressure detected by the saturation temperature detecting means (51) and the detected liquid refrigerant temperature of the liquid temperature detecting means (Th2) A liquid temperature output means (52) is provided for comparing the above and outputting a low temperature as the control liquid temperature. in addition,
The expansion valve (32) during cooling operation so that the superheat degree based on the control liquid temperature output by the liquid temperature output means (52) and the gas refrigerant temperature detected by the gas temperature detection means (Th3) becomes a predetermined value. An opening degree control means (53) for controlling the opening degree is provided.

Further, the means taken by the invention according to claim 2 is, as shown in FIG. 2, first, a compressor (21), a heat source side heat exchanger (24), and a heat source side expansion mechanism (25). And an operation control of an air conditioner in which a closed side main refrigerant circuit (11) is formed by sequentially connecting a use side expansion valve (32) with adjustable opening and a use side heat exchanger (31) Intended for devices. Then, a subcooling control means (55) for controlling the opening degree of the use side expansion valve (32) so that the degree of supercooling of the refrigerant in the use side heat exchanger (31) during the heating operation becomes a predetermined value is provided. ing. Further, a temperature difference determining means (56) for determining the temperature difference between the high pressure equivalent saturation temperature in the main refrigerant circuit (11) and the use side air temperature is provided. In addition, the control of the subcooling control means (55) during heating operation is stopped until the differential temperature determined by the differential temperature determination means (56) becomes a predetermined value or more, and the use side expansion valve (32) is set to a predetermined value. An opening holding means (57) for holding the opening is provided.

[0007]

With the above construction, in the invention according to claim 1,
First, while the liquid temperature detecting means (Th2) and the gas temperature detecting means (Th3) respectively detect the suction side liquid refrigerant temperature and the outlet side gas refrigerant temperature in the utilization side heat exchanger (31), the saturation temperature detecting means (51 ) Detects the low pressure equivalent saturation temperature on the suction side of the compressor (21). And the liquid temperature output means (52) is
The calculated liquid refrigerant temperature obtained by adding the predetermined temperature determined by the pressure loss based on the pipe length of the main refrigerant circuit (11) to the saturation temperature equivalent to the low pressure detected by the saturation temperature detecting means (51) and the liquid temperature detecting means (Th2). The lower temperature is output as the control liquid temperature by comparing with the detected liquid refrigerant temperature. That is, for example, the temperature obtained by adding 20 ° C. to the low pressure equivalent saturation temperature is set as the calculated liquid refrigerant temperature,
The liquid coolant temperature is compared with the actual liquid coolant temperature, and the lower temperature is set as the control liquid temperature. After that, the liquid temperature output means (5
The opening control means (53) controls the expansion valve (53) during cooling operation so that the superheat degree based on the control liquid temperature output by (2) and the gas refrigerant temperature detected by the gas temperature detection means (Th3) becomes a predetermined value. 32)
Will be controlled. That is, the expansion valve (32) is opened by a predetermined opening degree when the cooling operation is started.

Further, in the invention according to claim 2, the subcooling control means (55) expands the utilization side so that the degree of supercooling of the refrigerant in the utilization side heat exchanger (31) during the heating operation becomes a predetermined value. Valve (3
The opening of 2) is controlled. For example, the opening of the expansion valve (32) on the usage side is supercooled based on the temperature of the liquid refrigerant on the usage side and the saturation temperature corresponding to the high pressure. On the other hand, the differential temperature determination means (5
6) is the saturation temperature equivalent to the high pressure and the air temperature on the use side, for example,
The temperature difference from the room temperature is determined. Then, the opening degree holding means (57) heats until the temperature difference determined by the temperature difference determination means (56) becomes equal to or higher than a predetermined value, for example, the high pressure equivalent saturation temperature rises to 5 ° C. or more from the room temperature. Stop the control of the supercooling control means (55) at the time of operation and use side expansion valve (32)
Is maintained at a predetermined opening, and the user-side expansion valve (3
The opening of 2) is guaranteed.

[0009]

Therefore, according to the invention of claim 1,
When the cooling operation is started, the opening degree of the expansion valve (32) is controlled based on the saturation temperature equivalent to the low pressure, and the normal control is performed compared to the case where the opening degree is maintained at the predetermined opening degree for a certain period of time. Since the transition time can be shortened, the heat exchanger capacity can be fully exerted, and the air conditioning capacity can be improved. In addition, when the expansion valve (32) is superheated from the start-up during low capacity operation of long piping and during low outside air cooling operation, low pressure protection control is performed by controlling the expansion valve (32) in the direction of throttling. However, since the expansion valve (32) can be opened to a predetermined opening, the low-pressure protection control can be executed less frequently. On the other hand, according to the second aspect of the present invention, during the heating operation, the use side expansion valve (32) is kept at the predetermined opening degree until the temperature difference between the high pressure equivalent saturation temperature and the use side air temperature occurs. Therefore, the time required to shift to the normal control can be shortened compared to the case where the predetermined opening is maintained for a certain time as in the cooling operation, so that the heat exchanger capacity can be fully exhibited. Therefore, the air conditioning capacity can be improved. In particular, since the temperature can be quickly raised when the heating is started in the early morning, it is possible to improve comfort. Further, when the heating operation is restarted after the defrost operation, the use-side expansion valve (32) is opened to a predetermined opening degree, so that it is possible to prevent frost from occurring and to reduce the frequency of defrost operation. In addition, when the long pipe is connected to a large capacity and the low outside air heating operation is performed, the expansion valve on the utilization side is used from the beginning of control.
When supercooling control of (32), the system will diverge without opening the expansion valve (32), but since the expansion valve (32) is opened to a predetermined opening, divergence of the system is reliably prevented. can do.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 3 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) has a compressor (21) whose operating capacity is adjusted by an inverter (2a) whose output frequency is variably switched at intervals of 4 to 10 Hz within a range of 30 to 116 Hz, and the compressor (21). The oil separator (22) that separates the oil in the gas refrigerant discharged from, the four-way switching valve (23) that switches as shown by the solid line in the figure during cooling operation, and the dashed line in the figure during heating operation, and the cooling An outdoor heat exchanger (24) as a heat source side heat exchanger that functions as a condenser during operation and an evaporator during heating operation, and an outdoor fan attached to the outdoor heat exchanger (24)
(2F), an outdoor electric expansion valve (25) which is a heat source side expansion mechanism that performs a throttle action of the refrigerant during heating operation, a receiver (26) that stores the liquefied refrigerant, and an accumulator (27) as main devices. The respective devices such as the compressor (21) and the outdoor heat exchanger (24) that are built in are connected to the refrigerant pipe (4) so that the refrigerant can flow. In addition, the indoor unit (3)
An indoor fan (3F) attached to the indoor heat exchanger (31) and the indoor heat exchanger (31) as a utilization side heat exchanger that serves as a condenser during cooling operation and a condenser during heating operation, On the liquid pipe side of the refrigerant pipe (4) connected to the indoor heat exchanger (31), there is an indoor electric expansion valve (32) that regulates the refrigerant flow rate during heating operation and throttles the refrigerant during cooling operation. It is provided. And the outdoor unit (2) and the indoor unit
(3) is connected by a connecting pipe (41) which is a refrigerant pipe (4), and each device such as the compressor (21), the outdoor heat exchanger (24) and the indoor heat exchanger (31) is a refrigerant. A main refrigerant circuit (11) connected to the closed circuit by the pipe (4) is configured to release the heat obtained by heat exchange with the outdoor air to the indoor air.

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 for detecting an indoor temperature T1 (use side air temperature) which is the intake air temperature of the room. The sensors, (Th2) and (Th3) are indoor heat exchangers, respectively.
Liquid refrigerant temperature in liquid side and gas side refrigerant pipe (4) of (31)
Liquid temperature detecting means for detecting T2 and gas refrigerant temperature T3 and an indoor liquid temperature sensor and an indoor gas temperature sensor which are gas temperature detecting means, (Th4) is a discharge pipe for detecting a discharge pipe temperature T4 of the compressor (21). Sensor, (Th5) is the liquid refrigerant temperature of the outdoor heat exchanger (24)
Outdoor liquid temperature sensor that detects defrost etc. from T5, (Th6)
Is the suction refrigerant pipe on the downstream side of the suction pipe heat exchanger (2b).
The intake pipe sensor (Th7), which is located in (4) and detects the intake pipe temperature T6 of the compressor (21), is located at the air intake port of the outdoor heat exchanger (24) and indicates the outdoor intake air temperature. An outside air temperature sensor that detects an outside air temperature T7, (P1) is a high pressure sensor that is disposed on the discharge side of the compressor (21) and detects the high pressure side pressure of the main refrigerant circuit (11), (P2), A low pressure sensor that is arranged on the suction side of the compressor (21) and detects the low pressure side pressure of the main refrigerant circuit (11), (HPS)
Is a high-pressure pressure switch for protecting the compressor (21) disposed on the discharge side of the compressor (21). Then, each of the above electric expansion valves (2
5, 32) and sensors (Th1 to Th7) are connected to the control unit (5) by a signal line.
(5) receives the detection signals of the sensors (Th1 to Th7) and controls the opening and closing of the electric expansion valves (25, 32) and the capacity of the compressor (21).

Further, the control unit (15) has a feature of the present invention that a saturation temperature detecting means (51) and a liquid temperature output means (52) for controlling the indoor electric expansion valve (32) during cooling operation. ) And a cooling opening control means (53), and a heating opening control means (5) for controlling the outdoor electric expansion valve (25) and the indoor electric expansion valve (32) during heating operation.
4), a supercooling control means (55), a differential temperature determination means (56), and an opening degree holding means (57) are provided. The saturation temperature detecting means (51)
Is configured to detect the saturation temperature Te corresponding to the low pressure on the suction side of the compressor (21) from the low pressure side pressure detected by the low pressure sensor (P2). The liquid temperature output means (52),
The calculated liquid refrigerant temperature TH2 obtained by adding the predetermined temperature determined by the pressure loss based on the pipe length of the main refrigerant circuit (11) to the low temperature equivalent saturation temperature Te detected by the saturation temperature detection means (51) and the indoor liquid temperature sensor (Th2 ) Is compared with the detected liquid refrigerant temperature T2 detected by (1), and a low temperature is output as the control liquid temperature. Specifically, the liquid temperature output means (52) calculates the liquid refrigerant temperature TH2 by adding 20 ° C. to the low pressure equivalent saturation temperature Te.
(Te + 20), and this calculated liquid refrigerant temperature TH2 corresponds to the saturation temperature equivalent to the pressure in the indoor heat exchanger (31), and the lower of this calculated liquid refrigerant temperature TH2 and the detected liquid refrigerant temperature T2 is the control liquid temperature Th2D. I am trying. The cooling opening control means (53),
The indoor electric expansion valve (32) so that the superheat degree SH based on the control liquid temperature Th2D output by the liquid temperature output means (52) and the gas refrigerant temperature T3 detected by the indoor gas temperature sensor (Th3) becomes a predetermined value. ) Is controlled. That is, the opening control means (53), in the normal control, the indoor heat exchanger (31) based on the discharge pipe superheat degree of the discharge pipe temperature T4 of the compressor (21) and the high pressure equivalent saturation temperature Tc The target superheat degree is set and the wetness control is performed. At that time, when the low outside air cooling operation is started, the indoor liquid temperature sensor (Th2)
Also, at the liquid refrigerant temperature T2 and the gas refrigerant temperature T3 detected by the indoor gas temperature sensor (Th3), the liquid refrigerant temperature T2 is almost equal to the indoor temperature, so it is judged that the superheat degree SH is small and the indoor electric expansion valve (32 ) Will be controlled. Therefore, when the compressor (21) is started, the low-pressure side pressure immediately decreases, so that the superheat degree SH is calculated based on the low-pressure equivalent saturation temperature Te.
Are trying to control.

On the other hand, the heating opening control means (54) has a suction pipe temperature T6 of the compressor (21) detected by the suction pipe sensor (Th6) and a saturation corresponding to the low pressure detected by the saturation temperature detection means (51). temperature
The opening degree of the outdoor electric expansion valve (25) is controlled so that the superheat degree SH (T6-Te) based on Te and Te becomes a predetermined value. The supercooling control means (55) is configured to control the opening degree of the indoor electric expansion valve (32) so that the subcooling degree of the refrigerant in the indoor heat exchanger (31) during heating operation becomes a predetermined value. Has been done. That is, the supercooling control means (55) is a saturation temperature equivalent to the high pressure based on the liquid refrigerant temperature T2 detected by the indoor liquid temperature sensor (Th2) and the high pressure side pressure detected by the high pressure sensor (P1).
The opening degree of the indoor electric expansion valve (32) is controlled so that the degree of supercooling (T2-Tc) based on Tc becomes a predetermined value. The differential temperature determination means (56) is configured so that the saturation temperature Tc corresponding to the high pressure due to the high pressure of the high pressure sensor (P1) is the detection room temperature T1 of the room temperature sensor (Th1).
The temperature difference, which is a higher temperature difference, is discriminated. That is, since the liquid refrigerant temperature T2 on the indoor side at the time of stop is almost equal to the indoor temperature T1, when the high pressure equivalent saturation temperature Tc rises above the indoor temperature T1, a differential pressure in the main refrigerant circuit (11) occurs. Therefore, the temperature difference determining means (56) determines the temperature difference from the high pressure equivalent saturation temperature Tc and the room temperature T1. The opening degree holding means (57) is configured to hold the above-mentioned excess temperature during heating operation until the temperature difference between the high pressure equivalent saturation temperature Tc and the indoor temperature T1 becomes a predetermined value or more based on the temperature difference signal of the temperature difference determination means (56). Indoor electric expansion valve (32) by stopping the control of the cooling control means (55)
Is configured to be held at a predetermined opening degree. Specifically, the opening degree holding means (57) keeps the indoor electric expansion valve until the high pressure equivalent saturation temperature Tc becomes higher than the indoor temperature T1 by 5 ° C. or more.
Hold (32) at 2000 pulses for full opening. In other words, when starting low outside air heating operation, when restarting heating operation after oil return operation,
When the heating operation is restarted after the defrost operation, the operating frequency of the compressor (21) becomes low due to the low pressure droop, the high and low differential pressure becomes small, and the refrigerant does not flow easily. Since it is almost equal to T1, it is determined that the degree of supercooling is small, and control is performed to throttle the indoor electric expansion valve (32). Therefore, the opening degree holding means (57), until the high pressure equivalent saturation temperature Tc becomes high, the indoor electric expansion valve (32)
Is held fully open, then the supercooling control means (55),
The opening degree of the indoor electric expansion valve (32) is controlled from the fully opened state so that the degree of supercooling becomes a predetermined value.

Next, the operation of the air conditioner (1) will be described. In Fig. 3, during the cooling operation of the air conditioner, the four-way switching valve (23) is switched to the solid line side in the figure, and the auxiliary opening / closing valve (4c) of the auxiliary heat exchanger (4a) is always open, so that the compressor
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 valve (32) and evaporated in the indoor heat exchanger (31), and then transferred to the outdoor unit (2) via the communication pipe (41). It returns in a gas state and circulates so as to be sucked into the compressor (21). In other words, the liquid refrigerant cools the indoor air by exchanging heat with the indoor air in the indoor heat exchanger (31) 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. It is condensed in the exchanger (31), flows in the liquid state to the outdoor unit (2), is decompressed by the outdoor electric expansion valve (25), evaporates in the outdoor heat exchanger (24), and then returns to the compressor (21). To circulate. In other words, the gas refrigerant is the indoor heat exchanger (3
In 1), the indoor air is heated by exchanging heat with the indoor air and condensing.

The opening control of the indoor electric expansion valve (32) in the air conditioner (1) will be described with reference to FIGS. 4 and 5. FIG. 4 shows the control of the indoor electric expansion valve (32) during the cooling operation. The normal control of the indoor electric expansion valve (32) is started. First, at step ST1, the room temperature sensor (Th1) detects After setting the control constant A of the room temperature indoor electric expansion valve (32) from the average temperature of the room temperature T1 for 1 minute,
In step ST2, the minimum value Amin of the control constant A is calculated from the control constant A. Subsequently, in step ST3, it is determined whether the liquid refrigerant temperature T2 detected by the indoor liquid temperature sensor (Th2) is lower than -5 ° C. If the liquid refrigerant temperature T2 is lower than -5 ° C, From step ST3 to step ST4, the target superheat SHS is set to 5, while the liquid refrigerant temperature T2 is −
If the temperature is higher than 5 ° C, step ST3 to step ST5
Then, the target superheat SHS determination module is executed to determine the target superheat SHS.

After that, the above-mentioned steps ST4 and ST
From 5 to step ST6, check whether the temperature obtained by adding the amount of change to the liquid refrigerant temperature T2 detected by the indoor liquid temperature sensor (Th2) is higher than the calculated liquid refrigerant temperature TH2 calculated from the low pressure equivalent saturation temperature Te. judge. That is, the liquid temperature output means (52) is
It is determined whether the calculated liquid refrigerant temperature TH2 obtained by adding 20 ° C. to the low pressure equivalent saturation temperature Te is lower than the actual liquid refrigerant temperature T2 detected by the indoor liquid temperature sensor (Th2). When the actual liquid refrigerant temperature T2 is low, the process proceeds from step ST6 to step ST7, and the temperature obtained by adding the amount of change to the liquid refrigerant temperature T2 detected by the indoor liquid temperature sensor (Th2) is used as the control liquid temperature Th2D. And Also, the calculated liquid refrigerant temperature TH2 is the actual liquid refrigerant temperature.
If it is lower than T2, the above steps ST6 to ST
8, the calculated liquid refrigerant temperature TH2 is set as the control liquid temperature Th2D. After that, the process moves from step ST7 and step ST8 to step ST9, and the superheat degree SH is calculated from the control liquid temperature Th2D output by the liquid temperature output means (52) and the gas refrigerant temperature T3 detected by the indoor gas temperature sensor (Th3). And the control constant B is set to 3. Then, the process proceeds to step ST10, in which the opening degree control means (53) calculates the opening degree change amount of the indoor electric expansion valve (32) from the control constant B, the target superheat degree SHS, and the superheat degree SH to set the opening degree. Set. Next, in step ST11, it is determined whether the opening degree of the indoor electric expansion valve (32) to be controlled is smaller than the minimum value Amin of the control constant A set in step ST2, and the control opening degree is the minimum value Amin. When it is larger than the above, the control opening is controlled and returned. On the other hand, when the control opening is smaller than the minimum value Amin of the control constant A, the process moves from step ST11 to step ST12 to set the control opening. Minimum value Amin
Set to and return. That is, when the liquid refrigerant temperature T2 in the indoor heat exchanger (31) is high, the indoor electric expansion valve (32) is superheated based on the pressure-equivalent saturation temperature.

On the other hand, FIG. 5 shows the control of the indoor electric expansion valve (32) during the heating operation. First, in step ST21, after starting, the compressor is turned on during heating operation to drive the compressor (21), then the process proceeds to step ST22, the timer is started and the process proceeds to step ST23, and the indoor electric expansion valve (3
The initial opening degree determination subroutine of 2) is executed to determine the initial opening degree. Then, when the timer times out, the process proceeds from step ST23 to step ST24, and the high pressure sensor (P
Compared to the saturated temperature Tc corresponding to the high pressure based on the detected high pressure side of 1) and the average temperature T1 (AV) of the room temperature T1 detected by the room temperature sensor (Th1) for 1 minute, the saturated temperature Tc equivalent to the high pressure is the indoor temperature. It is determined whether it is higher than the average temperature T1 (AV) of T1 by 5 ° C. or more. Then, the saturation temperature Tc equivalent to the high pressure is the room temperature T1.
If the temperature is higher than the average temperature T1 (AV) of 5 ° C or more, the process proceeds from step ST24 to step ST25, and the indoor electric expansion valve (3
The normal opening determination subroutine of 2) is executed, and the supercooling control means (55) causes the indoor liquid refrigerant temperature T2 and the high pressure equivalent saturation temperature Tc.
As a result, the opening degree of the indoor electric expansion valve (32) is controlled by supercooling. On the other hand, the saturation temperature Tc equivalent to the above high pressure is the room temperature.
If the temperature is lower than the average temperature T1 (AV) of T1 by 5 ° C, the process proceeds from step ST24 to step ST26, and the opening holding means (57) holds the opening of the indoor electric expansion valve (32) at 2000 pulses of full opening. Then, the process returns to step ST24. That is, the indoor electric expansion valve (3
When the opening degree of 2) is held fully open, and then the saturation temperature Tc corresponding to the high pressure rises and the degree of supercooling increases, the process proceeds from step ST24 to step ST25, and the supercooling control means (55) drives the indoor electric Supercooling control is performed from the fully opened state of the expansion valve (32).

Therefore, according to this embodiment, when the cooling operation is started, the opening degree of the indoor electric expansion valve (32) is controlled on the basis of the low temperature pressure equivalent saturation temperature Te so that it is constant. Since the time required to shift to the normal control can be shortened as compared with the case where the opening degree is maintained at the predetermined time opening, the heat exchanger capacity can be sufficiently exerted, so that the air conditioning capacity can be improved. Further, when operating the indoor electric expansion valve (32) at a superheat degree from the time of start-up during the small capacity operation of the long pipe and during the low outside air cooling operation, the indoor electric expansion valve (32) is controlled to be narrowed, As a result, the low pressure protection control is performed, but since the indoor electric expansion valve (32) can be opened to a predetermined opening, the frequency of the low pressure protection control can be reduced. On the other hand, during heating operation,
The indoor electric expansion valve (32) is kept at a predetermined opening until the temperature difference between the high-pressure equivalent saturation temperature Tc and the room temperature T1 occurs. Since the time required to shift to the normal control can be shortened as compared with the case where the heat exchanger is held once, the heat exchanger capacity can be sufficiently exerted, and the air conditioning capacity can be improved. In particular, since the temperature can be quickly raised when the heating is started in the early morning, it is possible to improve comfort. Further, when the heating operation is restarted after the defrost operation, the indoor electric expansion valve (32) is opened to a predetermined opening degree, so that it is possible to prevent frost from occurring and to reduce the frequency of defrost operation. In addition, when the indoor electric expansion valve (32) is undercooled from the beginning of the control during long pipe connection with a large capacity and during low outside air heating operation, the system does not open without opening the indoor electric expansion valve (32). However, since the indoor electric expansion valve (32) is opened to a predetermined opening,
The divergence of the system can be reliably prevented.

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, ...). Further, the liquid temperature output means (52) is the calculated liquid refrigerant temperature TH2 by adding 20 ° C to the low pressure equivalent saturation temperature Te, but the 20 ° C is changed according to the pipe length. Good. Further, the temperature difference determining means (56) is configured to determine the temperature difference between the high pressure equivalent saturation temperature Tc and the room temperature T1, but in the invention according to claim 2,
Suction air temperature in the indoor unit (3) (indoor temperature T1)
And the temperature difference between the blown-air temperature and
Alternatively, the temperature difference may be determined based on the temperature difference between the liquid refrigerant temperature T2 in the room and the high pressure equivalent saturation temperature Tc. That is, the temperature of the blown air corresponds to the saturation temperature Tc corresponding to the high pressure, and the liquid refrigerant temperature T2 in the room corresponds to the room temperature T1 when the operation is stopped. Further, it goes without saying that the opening degree holding means (57) may hold the indoor electric expansion valve (32) at an opening degree other than full opening.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing the configuration of the invention of claim 2;

FIG. 3 is a refrigerant circuit diagram showing a refrigerant piping system of the air conditioner.

FIG. 4 is a control flow chart showing an opening control of an indoor electric expansion valve during a cooling operation.

FIG. 5 is a control flow chart showing opening control of an indoor electric expansion valve during heating operation.

[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 5 Controller 51 Saturation temperature detection means 52 Liquid temperature output means 53 Cooling opening control means 54 Heating opening control means 55 Supercooling control means 56 Differential temperature determination means 57 Opening holding means Th1 Room temperature sensor Th2 Indoor liquid temperature sensor (liquid Temperature detection means) Th3 indoor gas temperature sensor (gas temperature detection means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hitoshi Hashimoto 1304 Kanaoka-machi, Sakai City, Osaka Daikin Industry Co., Ltd.Kanaoka Factory, Sakai Factory (72) Hiroyuki Inoue 1304, Kanaoka-machi, Sakai City, Osaka Daikin Industry Co., Ltd. Sakai Plant Kanaoka Factory

Claims (2)

[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). Liquid temperature detection means (T for detecting the suction side liquid refrigerant temperature and the outlet side gas refrigerant temperature in the use side heat exchanger (31), respectively.
h2) and gas temperature detection means (Th3), saturation temperature detection means (51) for detecting the saturation temperature equivalent to the low pressure on the suction side of the compressor (21), and the pipe length of the main refrigerant circuit (11). The calculated liquid refrigerant temperature obtained by adding the predetermined temperature determined by the pressure loss based on the saturated temperature detecting means (51) to the low pressure equivalent saturation temperature detected by the saturation temperature detecting means (51) and the liquid refrigerant temperature detected by the liquid temperature detecting means (Th2) are low. A liquid temperature output means (52) for outputting a temperature as a control liquid temperature, and a superheat degree based on the control liquid temperature output by the liquid temperature output means (52) and the gas refrigerant temperature detected by the gas temperature detection means (Th3). And an opening degree control means (53) for controlling the opening degree of the expansion valve (32) during the cooling operation so that the above value becomes a predetermined value. 2. A compressor (21), a heat source side heat exchanger (24),
The heat source side expansion mechanism (25) and the use side expansion valve (3
2) and the use side heat exchanger (31) are connected in order to form a closed circuit main refrigerant circuit (11), which is an operation control device for an air conditioner, and uses the use side heat during heating operation. Supercooling control means (55) for controlling the opening degree of the use side expansion valve (32) so that the degree of supercooling of the refrigerant in the exchanger (31) becomes a predetermined value, and the high pressure in the main refrigerant circuit (11) The temperature difference determining means (56) for determining the temperature difference between the equivalent saturation temperature and the use side air temperature, and the above-mentioned excess temperature during heating operation until the temperature difference determined by the temperature difference determining means (56) becomes a predetermined value or more. An air conditioner operation control device comprising: an opening holding means (57) for stopping the control of the cooling control means (55) and holding the use side expansion valve (32) at a predetermined opening. .