JPH10311587A - Control method of air conditioner - Google Patents

Abstract

(57) [Problem] To prevent freezing of an indoor heat exchanger during non-setting temperature dry operation in an air conditioner having a two-pass indoor heat exchanger. SOLUTION: In an air conditioner in which an indoor heat exchanger constituting a refrigeration cycle has a two-pass structure and a refrigerant is circulated through the indoor heat exchanger to control room temperature, a capacity control operation by one pass with a valve 8 closed. The dry operation at the time executes the non-set temperature dry operation. In this non-setting temperature dry operation,
When the set temperature is equal to or lower than the predetermined value, the outdoor unit temperature is equal to or lower than the predetermined value, and when the compressor 1 has the minimum rotation speed, the timer counter unit 20a counts the state of the minimum rotation speed. When the state of the minimum number of revolutions continues for a predetermined time, data for reducing the expansion valve 5 by a predetermined value is transferred to the outdoor unit control device 21. Control unit 21 of outdoor unit control device 21
a restricts the expansion valve 5 and heats the indoor heat exchanger from the middle to the outlet to prevent icing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner having an indoor heat exchanger having a multi-pass structure and performing a capacity control operation. The present invention relates to a method for controlling an air conditioner that prevents freezing of an indoor heat exchanger.

[0002]

2. Description of the Related Art As shown in FIG. 4, for example, this air conditioner has a compressor 1, a four-way valve 2, a two-pass indoor heat exchanger 3,
The refrigeration cycle includes an outdoor heat exchanger 4, an expansion valve (electronic expansion valve) 5, and the like.

The two-pass indoor heat exchanger 3 supplies the refrigerant
It is divided into flow paths and has a large surface area, for example, a lambda type, which enables the indoor unit to be compact and secures a wide suction area to obtain a richer air volume, that is, powerful air blowing And a comfortable environment can be quickly established in the room.

As shown in FIG. 5, the air conditioner includes a room temperature sensor unit 6 for detecting a room temperature and an indoor heat exchanger 3.
An indoor heat exchange sensor unit 7 for detecting the temperature (heat exchange temperature) of the
A valve (solenoid valve) 8 provided on one refrigerant input side of the indoor heat exchanger 3, an indoor unit control device 9 for controlling the indoor unit and transmitting a control signal necessary for the outdoor unit, and detecting an outside air temperature Outside air temperature sensor 10 and superheat control (S
A suction temperature sensor unit 11 for detecting a refrigerant suction temperature of the compressor 1 and an outdoor unit control device 12 for controlling an indoor unit are provided. Therefore, according to the air conditioner having the above-described configuration, it is possible to perform control that is already known, that is, control (room temperature control) for circulating the refrigerant through the indoor heat exchanger and performing room temperature control to set the room temperature to the set temperature.

Further, for example, when a variable capacity operation is performed by the remote controller 13, the indoor unit control device 9 drives and closes the valve 8, sets the indoor heat exchanger 3 to one pass, and instructs the outdoor unit to control the capacity. Transmit to the control device 12 and the outdoor unit control device 12
Performs control according to the capacity control. A desired capacity can be obtained by this capacity control operation, and an appropriate environment can be provided by switching the capacity adaptively to the indoor environment.

When a dry operation is performed by the remote controller 13 during the capacity control operation, an instruction for the dry operation is transmitted from the indoor unit control device 9 to the outdoor unit control device 12, and the dry operation is performed. In the dry operation at the time of the capacity control operation, a non-set temperature equation is adopted. In the non-set temperature dry operation, the room temperature at the start of the capacity control operation is detected instead of the set temperature by the remote controller 13, and the detected room temperature is used. Is the set temperature (that is, the set temperature is changed), and the operating frequency of the compressor 1 is determined so that the room temperature is maintained at the set temperature.
And dry operation is performed. Thereby, deterioration of the indoor environment is suppressed, and indoor dehumidification is performed.

By the way, even in the non-set-temperature dry operation, in order to prevent the freezing of the indoor heat exchanger 3, its freezing state is predicted, that is, the freezing is determined based on the temperature of the indoor heat exchanger 3. The protection operation for predicting and stopping the operation of the compressor 1 is activated. Thereby, it is possible to prevent the heat exchange efficiency of the indoor heat exchanger 3 from decreasing.

[0008]

However, in the control method of the air conditioner, since the refrigerant flow path of the indoor heat exchanger 3 is changed from two paths to one path, the indoor heat exchanger 3 due to pressure loss is not used. (See FIG. 6), the freezing of the indoor heat exchanger 3 is likely to occur.
That is, the icing state is predicted based on the temperature (heat exchange temperature) near the inlet or the middle of the indoor heat exchanger 3,
This is because the icing prevention operation is performed, so that the icing prevention operation is likely to be delayed. In particular, the vicinity of the refrigerant outlet of the indoor heat exchanger 3 is likely to freeze. In addition, freezing occurs remarkably depending on not only the indoor temperature but also the outdoor temperature condition. For example, as the outside air temperature is lower, the temperature drop near the refrigerant outlet of the indoor heat exchanger 3 becomes larger, so that freezing occurs.

Moreover, even when the sensors of the indoor heat exchange sensor unit 7 used for the superheat control are arranged near the refrigerant inlet and in the middle of the indoor heat exchanger 3, freezing occurs due to the detected indoor heat exchange temperature. It is difficult to monitor the condition and to judge the icing. Further, when the freezing of the indoor heat exchanger 3 occurs, if the operation of the compressor 1 is stopped by the antifreezing operation, the deicing causes water leakage from the indoor unit.

Further, the freezing is predicted on the basis of the temperature (heat exchange temperature) of the indoor heat exchanger 3, and a protection operation for stopping the operation of the compressor 1 is activated. Stop. On the other hand, when starting the compressor 1, the compressor 1
Protection control (for example, control for operating at a predetermined operation frequency for one minute). Therefore, as shown in FIG. 7, the room temperature rises when the operation of the compressor 1 is stopped, and the room temperature decreases when the compressor 1 is restarted due to the release of icing prevention. The room temperature fluctuates due to the intermittent operation of the compressor 1), and not only the indoor comfort is impaired, but also the shutdown of the compressor 1 is an operation that does not conform to the non-set temperature dry operation described above.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to prevent freezing of an indoor heat exchanger without stopping the operation of a compressor in a non-set temperature dry operation. Without compromising comfort,
In addition, it is an object of the present invention to provide a method of controlling an air conditioner capable of improving the function of a non-setting temperature type dry operation.

[0012]

In order to achieve the above object, the present invention has an indoor heat exchanger constituting a refrigeration cycle having a multi-pass structure, and circulates a refrigerant through the indoor heat exchanger to control room temperature. On the other hand, a method for controlling an air conditioner, which controls opening and closing of a valve provided on a refrigerant input side of at least one of the plurality of paths, and enables a capacity control operation by changing a refrigerant flow path by opening and closing the valve. When performing the dry operation at the time of the capacity control operation, the current room temperature is set as the set temperature, the non-set temperature dry operation based on the set temperature is performed, and the set temperature is equal to or lower than a predetermined value. In the case, the outside air temperature and the number of revolutions of the compressor constituting the refrigeration cycle are monitored, and when the outside air temperature is equal to or lower than a predetermined value, the expansion valve constituting the refrigeration cycle is throttled according to the number of revolutions of the compressor. It is characterized in the thing.

According to the present invention, the indoor heat exchanger constituting the refrigeration cycle has a multi-pass structure, and the refrigerant is circulated through the indoor heat exchanger to control the room temperature. An air conditioner control method for controlling the opening / closing of a valve provided on an input side and changing a refrigerant flow path by controlling the opening / closing of the valve to enable a capacity control operation, wherein a dry operation is performed during the capacity control operation. The current room temperature is set as the set temperature, the non-set temperature dry operation is performed based on the set temperature, and if the set temperature is equal to or less than a predetermined value, the outside air temperature is equal to or less than a predetermined value; If the number of revolutions is the minimum number of revolutions for a predetermined time, the expansion valve constituting the refrigeration cycle is throttled.

According to the present invention, the indoor heat exchanger constituting the refrigeration cycle has a two-pass structure. The refrigerant is circulated through the indoor heat exchanger to control the room temperature, and one of the two passes is controlled.
An air conditioner that controls the opening and closing of a valve provided on the refrigerant input side of a path, and enables the capacity control operation by changing the refrigerant flow path by controlling the opening and closing of the valve. When performing, the current room temperature is set as the set temperature, a non-set temperature dry operation is performed based on the set temperature, and the outside air temperature and the compressor constituting the refrigeration cycle when the set temperature is equal to or lower than a predetermined value. When the outside air temperature is equal to or lower than a predetermined value, if the rotation speed of the compressor is the minimum rotation speed for a predetermined time, the expansion valve constituting the refrigeration cycle is throttled for a predetermined time. It is characterized by having.

In this case, the degree of restriction of the expansion valve may be such that the intermediate temperature of the indoor heat exchanger is higher than the temperature of the inlet of the indoor heat exchanger. Further, the degree of throttle of the expansion valve may be such that the suction refrigerant suction temperature of the compressor is higher than the temperature of the inlet of the indoor heat exchanger.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, FIG.
The same parts as those described above are denoted by the same reference numerals, and redundant description will be omitted.
The air conditioner control method according to the present invention focuses on heating from the middle to the outlet of the indoor heat exchanger when the expansion valve constituting the refrigeration cycle is squeezed during the non-set temperature dry operation. The expansion valve is throttled according to the temperature and the number of revolutions of the compressor to prevent freezing of the indoor heat exchanger without stopping the compressor.

Therefore, as shown in FIG. 1, the control device to which the control method of the air conditioner is applied includes a timer counter section 20a for counting a predetermined time and a control for instructing the throttle of the expansion valve 5 described above. An indoor unit control device 20 having a unit 20b and an outdoor unit control device 21 having a control unit 21a that throttles the expansion valve 5 in accordance with an instruction from the control unit 20b are provided.

The indoor unit control unit 20 has the function of the indoor unit control unit 9 shown in FIG. 5, and the control unit 20b is a microcomputer that executes the function.
1 has a function of the indoor unit control unit 12 shown in FIG. 5, and the control unit 21a is a microcomputer that executes the function.

Therefore, when receiving the remote control signal from the recommon 13, the indoor unit control device 20 controls the indoor unit and transfers necessary control signals to the outdoor unit control device 21. For example, when the operation of the capacity control operation is performed by the remote controller 13, the indoor unit control device 20 drives and closes the valve 8 and transfers the effect of the capacity control operation to the outdoor unit control device 21. When the dry operation is performed by the remote controller 13, the indoor unit control device 20 transfers an instruction (operating frequency code of the compressor 1) corresponding to the dry operation to the outdoor unit control device 21. Thus, the operation of the air conditioner is performed in the same manner as in the related art in accordance with the operation of the remote controller 13.

Next, the control method of the air conditioner having the above configuration will be described with reference to the flow chart of FIG. 2 and the graph of FIG. 3. First, since the capacity control instruction is issued by the remote controller 13, the indoor unit It is assumed that the control device 20 has closed the valve 8 and is executing the capacity control operation by one pass. For the capacity control operation, refer to the conventional example.

At this time, the indoor unit controller 20 determines whether or not there is a dry operation instruction from the remote controller 13 (step ST1). When the dry operation instruction is not issued, the capacity control operation is continued. When the dry operation instruction is issued, steps ST1 to ST1 are performed.
Proceed to 2 to execute the non-set temperature dry operation (see the conventional example).

Subsequently, it is determined whether or not a set temperature (room temperature at the start of the non-set temperature dry operation) used in the non-set temperature dry operation is equal to or lower than a predetermined value (for example, 18 ° C.) (step ST3). If the temperature is equal to or lower than 18 ° C., it is determined whether or not the outside air temperature is equal to or lower than a predetermined value (for example, 18 ° C.) (step 4). The outside air temperature is a value detected by the outside air temperature sensor 10 of the outdoor unit. For example, a value detected by a temperature sensor provided in a refrigerant pipe may be used. If the outside air temperature is equal to or lower than 18 ° C., it is determined whether or not the compressor 1 is at the minimum rotation speed (step ST).
5). In this case, since the indoor unit controller 20 transfers the operating frequency code of the compressor to the outdoor unit controller 21,
It is determined whether or not the rotation speed of the compressor 1 is at a minimum based on the operation frequency code.

Subsequently, only when the set temperature is equal to or lower than the predetermined value, the outside air temperature is equal to or lower than the predetermined value, and the compressor 1 is at the minimum rotation speed, the process proceeds to step ST6,
A timer A for a predetermined time a (for example, 20 to 40 minutes) is started. In order to monitor the outside air temperature and the rotation speed of the compressor 1, the process may return from step ST5 to step ST4. When the above condition is not satisfied, the non-setting temperature dry operation is continued.

Until the timer A times out, it is monitored whether or not the compressor 1 is at the minimum rotational speed (step ST).
7, ST8), when the state of the minimum number of revolutions lasts for 20 minutes to 40 minutes, the process proceeds from step ST7 to ST9, and the data (number of pulses) of the electronic expansion valve 5 is reduced by the outdoor unit in order to narrow the electronic expansion valve 5 by a predetermined value. Transfer to the control device 21. Then, the outdoor unit controller 21 heats the electronic expansion valve 5 from the middle to the outlet (of the refrigerant) from the middle of the indoor heat exchanger 3 to drive and throttle the electronic expansion valve 5 (see the dashed line in FIG. 3). That is, if the condition satisfying the above condition is further continued, icing of the indoor heat exchanger 3 cannot be avoided.

The degree of throttle of the electronic expansion valve 5 is determined by the temperature Ta detected by the inlet temperature sensor 7a provided near the refrigerant inlet of the indoor heat exchanger 3 and the temperature Tb detected by the intermediate temperature sensor 7b provided near the middle thereof. It is determined, for example, such that Tb ≧ Ta + 1 ° C. Thereby, the vicinity of the entrance of the indoor heat exchanger 3 is not heated,
In addition, there is no overheating from the middle of the indoor heat exchanger 3 to the vicinity of the outlet, and the indoor environment does not deteriorate (see the solid line in FIG. 3). Inlet temperature sensor 7a and intermediate temperature sensor 7
b corresponds to the indoor heat exchange sensor unit 7 shown in FIG. 5 and is already provided for use in superheat control. For example, it is not necessary to provide a new sensor near the exit. When the indoor heat exchange sensor unit 7 shown in FIG. 5 is only the inlet temperature sensor 7a, a suction temperature sensor unit 11 used for superheat control is used instead of the intermediate temperature sensor 7b, and the suction temperature sensor unit 11 is used. Detected temperature T
The degree of throttle of the electronic expansion valve 5 may be determined so that the relationship between c and Ta satisfies Tc> Ta. In this case, it is not necessary to provide a new sensor near the outlet of the indoor heat exchanger 3 as described above.

Subsequently, the electronic expansion valve 5 is throttled to control the heating of the indoor heat exchanger 3 after the middle, and the timer counter 20a is operated for a predetermined time (for example, 10 minutes to 20 minutes).
The timer B for minutes is started (step ST10).
After 10 to 20 minutes have elapsed (step ST1)
1) Returning to step ST3, the non-set temperature dry operation is continued, and the above steps are repeated. In this case, the electronic expansion valve 5 may be returned to the original state, that is, the heating control may be canceled and the opening / closing control of the electronic expansion valve 5 may be returned to the original state.

If the rotational speed of the compressor 1 is not at the minimum while monitoring whether the compressor 1 is at the minimum rotational speed, the process proceeds from step ST8 to ST12 to reset the timer. Thereafter, the process returns to step ST3 and repeats the above steps during the non-set-temperature dry operation. That is, when the rotation speed of the compressor 1 increases, the possibility of icing on the indoor heat exchanger 3 decreases. In the non-set-temperature dry operation, since the set temperature is the room temperature at the start of the operation, the process may return to step ST4 after the process of step ST12.

As described above, in the non-set temperature dry operation, the set temperature and the outside air temperature are low and the compressor 1
When the condition of the minimum number of rotations continues, the electronic expansion valve 5 is throttled because it is determined that the freezing of the indoor heat exchanger is a matter of time. Therefore, since the temperature rises from the middle of the indoor heat exchanger 3 to the vicinity of the outlet, that is, heating occurs, icing which is particularly likely to occur at the outlet from the middle of the indoor heat exchanger 3 is prevented (freezing is avoided).
can do. In addition, since the operation of the compressor 1 does not need to be stopped, the room temperature does not decrease due to the conventional restart (operation at a predetermined operation frequency for one minute), and the indoor comfort is not impaired. It also improves the function of temperature dry operation.

[0029]

As described above, according to the first aspect of the air conditioner control method, in the dry operation during the capacity control operation (in the non-set temperature dry operation), the set temperature is set to the predetermined value. In the following cases, the outside air temperature and the number of rotations of the compressor were monitored, and the expansion valve constituting the refrigeration cycle was throttled according to the outside air temperature and the number of rotations of the compressor. Freezing of the exchanger can be prevented, resulting in no freezing, preventing water leaks in the indoor units, and without stopping the operation of the compressor, without compromising the indoor comfort. There is an effect that the function of the set temperature dry operation can be improved.

According to the second aspect of the present invention, in the dry operation during the capacity control operation (in the non-set temperature dry operation), when the set temperature is equal to or lower than the predetermined value, the outside air temperature is equal to or lower than the predetermined value, and the compressor rotates at the minimum speed. When the number is a number, the expansion valve constituting the refrigeration cycle is throttled, so that when the set temperature and the outside air temperature are low, and when the compressor continues at a minimum speed for a predetermined time, icing occurs in the indoor heat exchanger. Although it becomes easier, by squeezing the expansion valve, the indoor heat exchanger can be heated from the middle to the outlet, so that icing can be prevented, and as a result, icing does not occur. No water leakage, no need to stop the operation of the compressor, no loss of indoor comfort, and improved dry operation with no set temperature A.

According to the third aspect of the present invention, in the dry operation during the capacity control operation using one of two pulses (in the non-set temperature dry operation), when the set temperature is equal to or lower than the predetermined value, the outside air temperature is equal to or lower than the predetermined value. When the compressor is at the minimum rotation speed for a predetermined time, the expansion valve constituting the refrigeration cycle is throttled for a predetermined time, so that the indoor heat exchanger passes from the middle to the outlet for a predetermined time. Since the heating can be performed, the icing can be prevented, and as a result, the icing does not occur, so that there is no water leakage of the indoor unit, and after a lapse of a predetermined time, the operation returns to the non-setting temperature dry operation, and Since it is not necessary to stop the operation of the compressor, there is an effect that the function of the non-set-temperature dry operation can be improved without impairing indoor comfort.

According to the invention described in claim 4, according to claim 1,
The degree of restriction of the expansion valve in 2 or 3 is such that the intermediate temperature of the indoor heat exchanger of the indoor heat exchanger is higher than the temperature of the inlet. The vicinity of the refrigerant inlet of the heat exchanger is not heated, that is, deterioration of the indoor environment can be suppressed, and there is no need to provide a new temperature sensor.

According to the invention described in claim 5, according to claim 1,
The degree of throttle of the expansion valve in 2 or 3 is such that the suction refrigerant suction temperature of the compressor is higher than the temperature of the inlet of the indoor heat exchanger. Because the vicinity of the refrigerant inlet of the heat exchanger is not heated, that is, it is possible to suppress deterioration of the indoor environment, and because there is no need to provide a new temperature sensor,
There is an effect that the cost is not increased.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a control device according to an embodiment of the present invention, to which an air conditioner control method is applied.

FIG. 2 is a schematic flowchart for explaining the operation of the control device shown in FIG. 1;

FIG. 3 is a schematic graph for explaining the operation of the control device shown in FIG. 1;

FIG. 4 is a schematic configuration diagram illustrating a refrigeration cycle of the air conditioner.

FIG. 5 is a schematic block diagram of a control device of a conventional air conditioner.

FIG. 6 is a schematic graph for explaining the operation of the control device shown in FIG. 5;

FIG. 7 is a schematic graph for explaining the operation of the control device shown in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 3 Indoor heat exchanger 5 Expansion valve (electronic expansion valve) 6 Room temperature sensor part 7 Indoor heat exchange sensor part 7a Inlet temperature sensor 7b Intermediate temperature sensor 8 Valve (solenoid valve) 9,20 Indoor unit control device 10 Outside air temperature Sensor unit 11 Suction temperature sensor unit 20a Timer counter unit (timers A and B) 20b, 21a Control unit (microcomputer)

Claims (5)

[Claims] An indoor heat exchanger constituting a refrigeration cycle has a multi-pass structure, and a refrigerant is circulated through the indoor heat exchanger to control room temperature, and at least one of the plurality of passes has a refrigerant input. Open / close control of a valve provided on the side, a method of controlling an air conditioner that enables a capacity control operation by changing the refrigerant flow path by opening / closing control of the valve, when performing a dry operation during the capacity control operation, The current room temperature is used as the set temperature, a non-set temperature dry operation is performed based on the set temperature, and when the set temperature is equal to or lower than a predetermined value, the outside air temperature and the number of rotations of the compressor constituting the refrigeration cycle are set. And controlling the expansion valve constituting the refrigeration cycle according to the rotation speed of the compressor when the outside air temperature is equal to or lower than a predetermined value. 2. An indoor heat exchanger constituting a refrigeration cycle has a multi-pass structure, and a refrigerant is circulated through the indoor heat exchanger to control room temperature, and at least one of the plurality of passes has a refrigerant input. Open / close control of a valve provided on the side, a method of controlling an air conditioner that enables a capacity control operation by changing the refrigerant flow path by opening / closing control of the valve, when performing a dry operation during the capacity control operation, The current room temperature is used as the set temperature, and the non-set temperature dry operation is performed based on the set temperature.When the outside air temperature is equal to or less than the predetermined value when the set temperature is equal to or less than the predetermined value, the compressor of the compressor is used. An air conditioner control method, wherein the expansion valve constituting the refrigeration cycle is throttled if the rotation speed is the minimum rotation speed for a predetermined time. 3. An indoor heat exchanger constituting a refrigeration cycle has a two-pass structure, in which a refrigerant is circulated through the indoor heat exchanger to control room temperature, and a refrigerant input side of one of the two passes is provided. An air conditioner that controls the opening and closing of a valve provided in the air conditioner and enables the capacity control operation by changing the refrigerant flow path by the opening and closing control of the valve. Is the set temperature, and performs the non-set temperature dry operation based on the set temperature, and monitors the outside air temperature and the rotation speed of the compressor constituting the refrigeration cycle when the set temperature is equal to or lower than a predetermined value. When the outside air temperature is equal to or lower than a predetermined value, if the rotation speed of the compressor is a minimum rotation speed for a predetermined time, the expansion valve constituting the refrigeration cycle is throttled for a predetermined time. Air conditioner Control method. 4. The air conditioner according to claim 1, wherein the degree of restriction of the expansion valve is such that the intermediate temperature of the indoor heat exchanger is higher than the temperature of the inlet of the indoor heat exchanger. Control method. 5. The air conditioner according to claim 1, wherein the degree of throttle of the expansion valve is such that the suction refrigerant suction temperature of the compressor is higher than the temperature of the inlet of the indoor heat exchanger. Control method.