JP2003240311A - Control method for air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct valve opening of an electronic expansive valve in accordance with an operational rotating speed of a compressor. <P>SOLUTION: A frequency zone corresponding to the operational rotating speed of the compressor is determined (ST3), a fixed pulse corresponding to the selected frequency zone is read out in reference to a valve opening table, and the electronic expansive valve is controlled on the basis of the read-out fixed pulse (ST4). The present fixed pulse is corrected by adding +5 when the temperature difference between a room temperature Ti and an indoor heat exchange temperature Tn is smaller than a predetermined value K to control the opening of the expansive valve on the basis of the corrected value (ST5-ST7). When the temperature difference becomes K+2°C or more, the present fixed pulse is returned to the original value before correction, and the opening of the expansive valve is controlled on the basis of the returned fixed pulse. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control technique of an electronic expansion valve which is a refrigerant flow rate adjusting means included in a refrigeration cycle of an air conditioner, and more specifically, it controls the electronic expansion valve appropriately. The present invention relates to a control method of an air conditioner for improving indoor comfort.

[0002]

2. Description of the Related Art An air conditioner has a refrigeration cycle including a compressor 1, a four-way valve 2, an indoor heat exchanger 3, an outdoor heat exchanger 4 and an electronic expansion valve 5, as shown in FIG. The room temperature is controlled by switching the four-way valve 2 according to the operation (including the dry operation) or the heating operation to circulate the refrigerant in a predetermined manner.

Therefore, as shown in FIG. 8, the air conditioner is provided with an indoor unit control section 6 and an outdoor unit control section 7 which are composed of a microcomputer and a drive circuit, and the indoor unit control section 6 instructs the remote control 8 to operate. According to the instruction, the indoor fan 9 is controlled, and a predetermined command (such as an operating frequency according to the difference between the room temperature and the set value) is transferred to the outdoor unit control unit 7, and the outdoor unit control unit 7 receives the command. , The four-way valve 2, the electronic expansion valve 5, the outdoor fan 10, etc. are controlled.

At this time, in the air conditioner, the operating speed (operating frequency) of the compressor 1 is determined according to the difference between the room temperature detected by the indoor temperature sensor 11 and the set temperature of the remote controller 8, while the electronic The valve opening of the expansion valve 5 is determined according to the operating speed of the compressor 1.

[0005]

As described above, the valve opening degree of the electronic expansion valve 5 is determined according to the operating speed. However, in the conventional control method, the valve opening degree of the electronic expansion valve 5 is compressed. Since it is uniquely determined only based on the operating rotational speed of the machine 1, if the load changes, the throttle amount of the electronic expansion valve 5 will not match, and the room temperature control cannot be said to be optimal.

Specifically, if the load (room temperature) changes greatly, the electronic expansion valve 5 uniquely determined in accordance with the operating speed.
The valve opening of is greatly deviated from the optimum value. For example,
If the indoor environment is in a high temperature and high humidity state during the cooling operation, the discharge temperature of the compressor 1 rises abnormally and adversely affects the refrigeration cycle, or the overheated region of the evaporator expands and the indoor fan 9 Condensation may form on the inside of the room, which may lead to deterioration of the indoor environment.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to always set the valve opening degree of the electronic expansion valve to an appropriate value according to the operating speed (operating frequency) of the compressor. The air that prevents the expansion of the overheated area of the evaporator, prevents the condensation on the indoor fan, suppresses the abnormal rise in the discharge temperature of the compressor, and improves the comfort of the indoor environment. It is to provide a control method of a harmony machine.

[0008]

In order to achieve the above object, the present invention has a refrigeration cycle including a compressor, a four-way valve, an indoor heat exchanger, an outdoor heat exchanger and an electronic expansion valve. In an air conditioner control method for controlling a valve opening of an expansion valve to control a room temperature, an operating speed region of the compressor is divided into a plurality of frequency zones, and a valve of the electronic expansion valve is provided for each frequency zone. A valve opening table that sets the opening is provided, and the valve opening corresponding to the frequency zone to which the operating speed of the compressor belongs is read from the valve opening table to control the electronic expansion valve, while at least the cooling operation is performed. At this time, a temperature difference between the room temperature and the indoor heat exchange temperature is calculated, and when the calculated temperature difference is smaller than a predetermined value, the current opening degree of the electronic expansion valve is corrected to a predetermined value.

In the present invention, the plurality of frequency zones are different when the operating frequency of the compressor is rising and when the operating frequency is falling, and in the same frequency zone, the set frequency value is lower when the operating frequency is lower than when the operating frequency is rising. It is preferable that the electronic expansion valve can be appropriately controlled without causing hunting.

Further, when the operating speed of the compressor is higher than a predetermined value during the cooling operation or when the outside air temperature is higher than the predetermined value, the electronic expansion due to the temperature difference between the room temperature and the indoor heat exchange temperature is performed. It is preferable to correct the current opening of the valve.

As a result, even when the rotation speed of the compressor is in the low range in the environment of low outside air temperature, even when the rotation speed of the compressor is in the low range and the outside air temperature is low, the compression is performed. The reliability of the machine is secured.

After correcting the valve opening of the electronic expansion valve, it is preferable to detect the temperature difference and return the electronic expansion valve to the opening before correction when the temperature difference exceeds a predetermined value. As a result, the opening degree of the electronic expansion valve is appropriately controlled, that is, the indoor environment is kept good.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to FIGS. Note that FIG.
Among them, the same parts as those in FIG. 8 are denoted by the same reference numerals, and the duplicated description is omitted. For the configuration of the refrigeration cycle, refer to FIG. 7.

As shown in FIG. 2, in carrying out the present invention, the control device according to the first embodiment divides the operating rotational speed region of the compressor 1 into a plurality of frequency zones (see FIG. 3) and sets each frequency. The valve opening table (fixed pulse table) of the following Table 1 in which the valve opening (fixed pulse) of the electronic expansion valve 5 is uniquely set for each zone is stored in the internal memory 20a,
When the difference between the room temperature Ti and the indoor heat exchange temperature (evaporation temperature) Tn is smaller than a predetermined value K (for example, 2 to 3 ° C.), the fixed pulse in Table 1 below is corrected and the corrected fixed pulse (for example, in Table 2 below) is corrected. Electronic expansion valve 5 according to the valve opening table)
An outdoor unit control unit (which also has the function of the outdoor unit control unit 7) 20 for controlling the opening degree is provided.

[0015]

[Table 1]

[0016]

[Table 2]

Explaining Table 1 above, the operating speed region of the compressor 1 is divided into a plurality of frequency zones A to P, and the fixed pulse of the electronic expansion valve 5 is increased as the operating speed increases. (The valve opening is increased).

In this case, as shown in FIG. 3, the frequency zones are assigned differently when the operating frequency is rising and when it is falling, and the frequency zone at the time of falling is set lower than the frequency zone at the time of rising. Electronic expansion valve 5
Control has hysteresis. In addition, the frequency zone in the low region of the operating speed (in this example, A to E
For zones), the same allocation is made during the ascent and descent.

In Table 2 above, when the difference (Ti-Tn) between the room temperature Ti and the evaporation temperature (indoor heat exchange temperature) Tn becomes smaller than K (see the broken line arrow in FIG. 4), the predetermined zone of Table 1 above is shown. This shows a fixed pulse corrected by adding 5 pulses to the fixed pulse.

After correcting the fixed pulse in this way,
When the difference between the room temperature Ti and the evaporation temperature Tn becomes K + 2 ° C. or more (see the broken line arrow in FIG. 4), the correction of the fixed pulse is canceled, that is, the control using the fixed pulse without correction shown in Table 1 is restored. It will be.

Next, the operation of the control device having the above configuration will be described in detail with reference to the flowchart of FIG. First, the indoor unit control unit 6 reads the room temperature detected by the indoor temperature sensor 11, the set temperature and the operation mode (for example, cooling operation) by the remote controller 8 (step ST1), and determines the compressor 1 according to the difference between the set temperature and the room temperature. Operating frequency (rotation speed)
Is determined (step ST2) and the operating speed and the operating mode are transmitted to the outdoor unit controller 20, while the indoor fan 9
Control the rotation.

Then, the outdoor unit controller 20 determines the frequency zone corresponding to the operating speed of the compressor 1 (step ST3), and the fixed pulse corresponding to this frequency zone is stored in the valve opening table shown in Table 1 above. It is read out by reference, and the opening degree of the electronic expansion valve 5 is controlled according to this fixed pulse (step ST4). When the operating speed of the compressor 1 in the cooling operation is in the frequency zone H, the electronic expansion valve 5
Is controlled to be the opening degree of the fixed pulse 40.

In this way, the compressor 1, the four-way valve 2, the electronic expansion valve 5, the outdoor fan 10, etc. are controlled in accordance with the instruction from the indoor unit control section 6 and the refrigeration cycle is operated according to the setting operation of the remote controller 8. And control the room temperature.

Then, room temperature Ti and indoor heat exchange temperature Tn
Is detected (step ST5). In this case, it is preferable to request the room temperature Ti and the indoor heat exchange temperature Tn to the indoor unit control unit 6 and use the room temperature Ti and the indoor heat exchange temperature Tn detected by the indoor unit control unit 6.

Then, the room temperature Ti and the indoor heat exchange temperature Tn
And the temperature difference (Ti-Tn) is calculated.
It is determined whether n) is smaller than the predetermined value K (step ST6). When the temperature difference (Ti-Tn) is larger than the predetermined value K, the process returns to step ST5 and the above-described processing is repeated. That is, for example, the fluctuation of the load is extremely small,
Even if the opening degree of the electronic expansion valve 5 is not changed, the evaporator does not overheat, and therefore the current opening degree of the electronic expansion valve 5 is maintained.

When the temperature difference (Ti-Tn) is smaller than the predetermined value K, the fixed pulse in the valve opening table (Table 1) is +5.
The pulse is added, that is, the opening of the electronic expansion valve 5 is controlled by the fixed pulse of the valve opening table shown in Table 2 (step ST7). That is, when the temperature difference (Ti-Tn) is smaller than the predetermined value K, the throttle of the electronic expansion valve 5 is in a tight state due to the current load, the evaporator abnormally overheats, and the overheat region expands. Is.

For example, while the current operating frequency is in the H zone, the fixed pulse of the valve opening degree of the electronic expansion valve 5 is changed from 40 to 45. As a result, the throttle of the electronic expansion valve 5 changes according to the load state, that is, the electronic expansion valve 5 has an appropriate valve opening degree even if the load changes.

Then, the room temperature Ti and the indoor heat exchange temperature Tn are again measured.
Is detected and it is determined whether or not the temperature difference (Ti-Tn) is K + 2 ° C or more (step ST8). When the temperature difference (Ti-Tn) is smaller than K + 2 ° C, the process of step ST8 is repeated to obtain the temperature difference (Ti-Tn).
When the temperature becomes K + 2 ° C. or higher, the opening degree correction of the electronic expansion valve 5 is canceled, that is, the fixed pulse is returned to the value in Table 1 (the valve opening degree is returned to the original value) (step ST9).

For example, the fixed pulse of the electronic expansion valve 5 is 40
If corrected to 45, the electronic expansion valve 5 is controlled to return to the fixed pulse 40. Then, the routine ends. It should be noted that the routine shown in FIG. 1 is repeated every predetermined time, or every time the room temperature or the set temperature is changed, or the operating speed of the compressor 1 is changed.

Further, as shown in Table 2, there is a zone (L zone or P zone) in which the fixed pulse in Table 1 is not corrected, but when the opening of the throttle of the electronic expansion valve 5 is large, the load is increased. It is because the influence of the fluctuation is small, that is, it is hardly influenced.

As described above, the operating speed (frequency) region of the compressor 1 is divided into a plurality of frequency zones, and the valve opening degree of the electronic expansion valve 5 is uniquely controlled according to the frequency zones. The control frequency of the valve opening degree of the electronic expansion valve 5 is lower than before, that is, the durability of the electronic expansion valve 5 is increased, and the reliability is improved, and the suction temperature, the indoor heat exchange temperature and the outdoor heat are increased. Since the cross temperature is not used, the accuracy of the room temperature control due to the detection error of the temperature sensor does not decrease, that is, the accuracy can be improved and the cost can be reduced by the temperature sensor.

Further, the difference between the room temperature Ti and the indoor heat exchange temperature Tn is detected during the cooling operation, and the temperature difference (Ti-Tn) is used to predict the amount of superheat of the indoor heat exchanger (evaporator). Since the fixed pulse of the electronic expansion valve 5 is corrected when (Ti-Tn) becomes small, for example, the indoor heat exchanger is prevented from overheating due to load fluctuations, that is, the electronic expansion valve with respect to the load. Preventing the throttle of No. 5 from becoming tight, preventing the expansion of the overheated area of the evaporator, preventing condensation on the indoor fan, and suppressing abnormal rises in the discharge temperature of the refrigerant, and thus achieving optimum cooling operation. realizable.

The correction of the fixed pulse is performed over the entire operating speed of the compressor 1, but when the operating speed is low and the outside air temperature is low, the electronic expansion valve 5 is corrected. When the opening degree becomes large, there may occur a problem that the reliability of the compressor cannot be ensured.

Therefore, in the second embodiment of the present invention, as shown in FIG.
As shown in step ST4 and step S4 of the first embodiment,
During the process of T5, a process of determining whether or not the operating speed f of the compressor 1 is higher than a predetermined value (for example, 30 rps) is added. Note that, in FIG. 5, the same processing parts as those in FIG.

2 and 5, the outdoor unit controller 3
0 continues the processing of the above-described embodiment (processing after step ST5) only when the operating speed f is larger than 30 rps, and if the operating speed f is 30 rps or less, performs the processing after step ST5. No (step ST1
0).

Therefore, the fixed pulse for controlling the opening degree of the electronic expansion valve 5 is corrected only in the region where the operating speed f is relatively high. As a result, the reliability of the compressor can be ensured even when the outside air temperature is low.

Further, in the third embodiment of the present invention, as shown in FIG. 6, steps ST4 and ST of the first embodiment described above are performed.
During the process of 5, the outside air temperature To is detected, and a process of determining whether or not the outside air temperature To is higher than the predetermined value A is added. Note that, in FIG. 6, the same processing parts as those in FIG.

2 and 6, the outdoor unit control section 4
0 detects the outside air temperature To according to the detection signal from the outside air temperature sensor 41, and the detected outside air temperature To is the predetermined value A.
Only when the temperature is higher, the above-described processing of step ST5 and below is executed, and if the outside air temperature To is below the predetermined value A,
The processing after step ST5 is not performed (step S
T11).

Therefore, the fixed pulse for controlling the opening degree of the electronic expansion valve 5 is corrected only when the outside air temperature To is high. As a result, the reliability of the compressor can be ensured even when the outside air temperature is low.

In this case, the outside air temperature sensor 41 is required, but the ordinary air conditioner can also be used because the outside air temperature sensor 41 is already provided, that is, the cost does not increase. I'm done. The processing of step ST10 shown in FIG. 5 and step ST shown in FIG.
You may make it perform the process of 11 together.

[0041]

As described above, according to the present invention,
The operating speed range of the compressor included in the refrigeration cycle is divided into a plurality of frequency zones, and a valve opening table that sets the valve opening of the electronic expansion valve is stored for each frequency zone. When controlling the valve opening of the electronic expansion valve that constitutes, refer to the valve opening table by determining the frequency zone corresponding to the operating speed of the compressor, while reading the valve opening corresponding to the frequency zone, While controlling the electronic expansion valve according to this valve opening degree, the current opening degree of the electronic expansion valve is corrected to a predetermined value when the temperature difference between the room temperature and the indoor heat exchange temperature during the cooling operation is smaller than a predetermined value. Therefore, the opening of the electronic expansion valve, which is determined according to the operating frequency of the compressor, is always set to an appropriate value to prevent the expansion of the overheated area of the evaporator and to prevent dew condensation on the indoor fan. Abnormal discharge temperature Suppressing the rise, there is an effect that it leads to an improvement in comfort in the indoor environment.

[Brief description of drawings]

FIG. 1 is an operation flowchart of a control method for an air conditioner according to a first embodiment of the present invention.

FIG. 2 is a schematic block diagram of a control device to which the control method for an air conditioner of the present invention is applied.

FIG. 3 is an explanatory diagram in which the operating speed region of the compressor is divided into a plurality of frequency zones.

FIG. 4 is an explanatory diagram showing threshold levels when the operating speed is increased and when the operating speed is decreased.

FIG. 5 is an operation flowchart of a control method for an air conditioner according to a second embodiment of the present invention.

FIG. 6 is an operation flowchart of a method for controlling an air conditioner according to a third embodiment of the present invention.

FIG. 7 is a schematic configuration diagram for explaining a refrigeration cycle of a conventional air conditioner.

FIG. 8 is a schematic block diagram for explaining a control device for a conventional air conditioner.

[Explanation of symbols]

1 compressor 5 Electronic expansion valve 6 Indoor unit control unit 7, 20, 30, 40 Outdoor unit control unit 8 remote control 11 Indoor temperature sensor 20a internal memory 41 Outside temperature sensor f Operating speed of the compressor To outside temperature

Claims (5)

[Claims] 1. An air conditioner that has a refrigeration cycle including a compressor, a four-way valve, an indoor heat exchanger, an outdoor heat exchanger, and an electronic expansion valve, and controls the valve opening of the electronic expansion valve to control the room temperature. In the control method of the machine, the operating speed region of the compressor is divided into a plurality of frequency zones, and a valve opening table that sets the valve opening of the electronic expansion valve for each of the frequency zones is provided. While controlling the electronic expansion valve by reading the valve opening degree corresponding to the frequency zone to which the operating speed belongs, from the valve opening degree table, calculate the temperature difference between the room temperature and the indoor heat exchange temperature at least during the cooling operation, A method for controlling an air conditioner, wherein the current opening of the electronic expansion valve is corrected to a predetermined value when the calculated temperature difference is smaller than a predetermined value. 2. The plurality of frequency zones are different when the operating frequency of the compressor is rising and when the operating frequency is falling, and in the same frequency zone, the set frequency value is set to be lower when the frequency is falling than when it is rising. 1. The method for controlling an air conditioner according to 1. 3. The present opening degree of the electronic expansion valve is corrected by the temperature difference only when the operating speed of the compressor is higher than a predetermined value during the cooling operation.
A method for controlling an air conditioner according to. 4. The control of the air conditioner according to claim 1, wherein the current opening degree of the electronic expansion valve is corrected by the temperature difference only when the outside air temperature is higher than a predetermined value during the cooling operation. Method. 5. After correcting the opening degree of the electronic expansion valve, the temperature difference between the room temperature and the indoor heat exchange temperature is detected, and when the temperature difference exceeds a predetermined value, the electronic expansion valve is opened. The control method for an air conditioner according to any one of claims 1 to 4, wherein the degree is returned to the opening before correction.