KR101270620B1 - Air conditioner and Control method of the same - Google Patents

Abstract

The present invention relates to an air conditioner capable of air conditioning of cooling or heating, and a control method thereof. In particular, when the difference between the condensation temperature and the liquid pipe temperature is within a preset value, the expansion valve is controlled according to the suction superheat, otherwise the expansion valve By reducing the opening amount of the expansion valve so as to reduce the opening degree of, it provides an air conditioner and a control method that can improve the system stability, reliability, performance by preventing a sudden decrease in the amount of refrigerant that can be circulated.

Air conditioner, compressor, expansion valve, suction superheat, discharge superheat

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner,

1 is a bird's-eye view of an air conditioner according to the present invention.

2 is an illustration of an air conditioner according to the present invention.

3 is a block diagram showing an air conditioner according to the present invention.

Figure 4 is a flow chart according to the main control method during the heating operation of the air conditioner according to the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS

2 ; Indoor heat exchanger 4; Indoor blower

6; Indoor electronic expansion valve 8; Indoor heat exchanger temperature sensor

10; An outdoor heat exchanger 12; Outdoor blower

14; Accumulators 15,16; compressor

17; Four-way valve 18; Outdoor electronic expansion valve

20; Outdoor heat exchanger temperature sensor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner and a control method thereof, and more particularly, to an air conditioner and a control method thereof in which the superheat control condition can be varied depending on the suction superheat and the discharge superheat when the compressor is running, at least during the heating operation. will be.

In general, an air conditioner is an air conditioning cycle consisting of a compressor, a condenser, an evaporator, and an expansion valve, which supplies air or hot air to a building or a room where the air conditioner is installed. Separated by.

The separation type and the integrated type are functionally the same, but the separation type installs an indoor heat exchanger (evaporator or condenser) in an indoor unit, and an outdoor heat exchanger (condenser or evaporator) and a compressor in an outdoor unit, and separates them from each other as refrigerant piping. The one-piece unit is an indoor heat exchanger, a compressor, an outdoor heat exchanger, and an expansion valve.

The integrated air conditioner includes a window type air conditioner installed directly by hanging a device on a window, and a duct type air conditioner connected to an intake duct and a discharge duct and installed outside the room. The separate type air conditioners include stand type air conditioners installed upright and wall-mounted air conditioners mounted on a wall.

In addition, the air conditioner may be classified into a cooling air conditioner that is used only for cooling, and a heat pump type air conditioner that may be used for both cooling and heating.

Recently, a multi-type air conditioner in which at least one outdoor unit and a plurality of indoor units are connected in series has been widely used.

Normally, such an air conditioner stabilizes the system by controlling the superheating degree of the expansion valve when the compressor starts, and controls the discharge superheating degree of the expansion valve when the system stabilizes.

However, in the air conditioner according to the prior art as described above, when the amount of refrigerant is excessively larger than the limit that the condenser can afford, two-phase saturated refrigerant, which is a mixture of liquid and gas, is discharged from the condenser, During the expansion and evaporation process, the refrigerant enters the compression process as a refrigerant phase that is not sufficiently vaporized.As the liquid phase refrigerant in the two phase refrigerant is caught by the accumulator, a considerable amount of refrigerant can be stored and circulated in the accumulator. As the amount of refrigerant is drastically reduced, there is a problem that adversely affects system stabilization and reliability.

The present invention has been made to solve the above problems of the prior art, the amount of refrigerant stored in the accumulator by reducing the amount of refrigerant circulation to increase the supercooling in the condenser when the amount of refrigerant exceeds the limit that can be accommodated in the condenser It is an object of the present invention to provide an air conditioner and a control method thereof which can prevent the amount of refrigerant that can be increased and circulated rapidly decreases.

In order to solve the above problems, the present invention provides that the expansion valve is controlled according to the suction superheat if the difference between the condensation temperature and the liquid pipe temperature is within the preset value, otherwise the opening amount of the expansion valve is reduced so that the opening value of the expansion valve is reduced. It provides a control method of the air conditioner.

When the difference between the condensation temperature and the liquid pipe temperature is not within a preset value, the opening amount of the expansion valve may be reduced by a predetermined ratio.

The control method of the air conditioner may be carried out during the heating operation during the cooling, heating operation.

The present invention also includes a compressor, a condenser, an expansion valve, and an evaporator in which the refrigerant is circulated in turn; The expansion valve is controlled in accordance with the suction superheat if the difference between the condensation temperature and the liquid pipe temperature measured in the condenser is within a preset value, otherwise it provides an air conditioner having a control unit which allows the opening amount of the expansion valve to be reduced.

In order to solve the above problems, the present invention includes an indoor heat exchanger, a compressor, an expansion valve, an outdoor heat exchanger, a four-way valve, an indoor electromagnetic expansion valve, an outdoor electromagnetic expansion valve for cooling and heating operation; The outdoor electromagnetic expansion valve is fully opened in the cooling operation, and in the case of heating operation, the expansion valve is controlled according to the suction superheat if the difference between the condensation temperature and the liquid pipe temperature is within the preset value, otherwise the opening amount of the expansion valve is reduced. An air conditioner having a control unit is provided.

The condensation temperature may be obtained by an indoor heat exchanger temperature sensor located in the indoor heat exchanger.

The liquid pipe temperature may be obtained by an outdoor unit pipe temperature sensor located at an inlet side of the outdoor electromagnetic expansion valve.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a bird's eye view of an air conditioner according to the present invention, FIG. 2 is a view showing an air conditioner according to the present invention, and FIG. 3 is a block diagram showing an air conditioner according to the present invention.

The air conditioner according to the present embodiment may be applied to various types of air conditioners. For convenience of description, a plurality of indoor units I installed in the interior of a building among the various types of air conditioners, and the indoor units I and It is configured to include an outdoor unit (M) (S1) (S2) and a control unit (not shown) for controlling the indoor unit (I) and the outdoor unit (M) (S1) (S2) connected through a refrigerant pipe (P). The present invention is a multi-type that is cooled or heated by using an air conditioning cycle, and the description is limited to the heat pump type.

Each indoor unit (I) is an indoor heat exchanger (2) in which the indoor air of the room where each indoor unit (I) is installed and a refrigerant exchange heat, and the indoor air in the room where each indoor unit (I) is installed, the indoor heat exchanger (2). An indoor blower (4) for blowing air in the air, and an indoor electromagnetic expansion valve (6), which is an expansion valve for reducing the refrigerant and controlling the flow rate of the refrigerant during the cooling operation.

The indoor heat exchanger (2) is an evaporator that allows the indoor air to be cooled while the liquid refrigerant is sucked during the cooling operation of the air conditioner and the sucked liquid refrigerant is evaporated by the indoor air in which the indoor unit (I) which requests the cooling operation is installed. The gaseous refrigerant is sucked during the heating operation of the air conditioner, and the sucked gaseous refrigerant is condensed by the indoor air in which the indoor unit I, which requested the heating operation, is installed.

The indoor heat exchanger 2 may be provided with an indoor heat exchanger temperature sensor 8 capable of sensing the temperature of the refrigerant passing through the indoor heat exchanger 2. The indoor heat exchanger temperature sensor 8 senses the evaporation temperature of the refrigerant evaporated in the indoor heat exchanger 2 when the indoor heat exchanger 2 acts as an evaporator during a cooling operation, and the indoor heat exchanger during a heating operation. Bar 2 serves as a condenser to sense the condensation temperature of the refrigerant condensed in the indoor heat exchanger (2).

The indoor blower 4 is rotated by the indoor motor unit 4a connected to the indoor motor unit 4a and the indoor motor unit 4a, which are controlled by the control unit 38 to generate power. It consists of the indoor fan 4b which produces a blowing force.

The plurality of outdoor units M, S1 and S2 include a main outdoor unit M that is always operated regardless of the load of the indoor unit I and a sub outdoor unit M that selectively operates according to the load of the indoor unit I S1) (S2).

The main outdoor unit M and the sub outdoor units S1 and S2 include an outdoor heat exchanger 10 for exchanging heat between outdoor air and refrigerant, an outdoor air blower 12 for blowing outdoor air to the outdoor heat exchanger 10, An accumulator 14 for extracting only the gas refrigerant, two compressors 15 and 16 for compressing the gas refrigerant extracted from the accumulator 14, a four-way valve 17 for switching the refrigerant flow, And an outdoor electronic expansion valve (18), which is an expansion valve controlled in accordance with the degree of superheat, so as to reduce the pressure of the refrigerant and regulate the flow rate of the refrigerant.

The outdoor heat exchanger (10) functions as a condenser for allowing the gaseous refrigerant to be sucked in the cooling operation of the air conditioner and causing the sucked gaseous refrigerant to be condensed by the outdoor air, and the liquid refrigerant is sucked in the heating operation of the air conditioner And serves as an evaporator for causing the sucked liquid refrigerant to be evaporated by the outdoor air.

The outdoor heat exchanger (10) may be provided with an outdoor heat exchanger temperature sensor (20) capable of sensing the temperature of the refrigerant passing through the outdoor heat exchanger (10). The outdoor heat exchanger temperature sensor 20 senses the condensation temperature of the refrigerant condensed in the outdoor heat exchanger 10 when the outdoor heat exchanger 10 acts as a condenser during the cooling operation, and the outdoor heat exchanger during the heating operation. Bar 10 acts as an evaporator senses the evaporation temperature of the refrigerant evaporated in the outdoor heat exchanger 10.

The outdoor air blower 12 includes an outdoor motor unit 12a controlled by the control unit 38 to generate power and an outdoor fan unit 12b connected to the outdoor motor unit 12a and driven by the power of the outdoor motor unit 12a And an outdoor fan 12b that generates a wind power while being rotated.

One of the two compressors 15 and 16 of the main outdoor unit M may be an inverter compressor and the other one may be a constant speed compressor.

The two compressors (15) and (16) of the sub outdoor units (S1) and (S2) may all be provided as constant speed compressors.

The suction side and the discharge side of the compressors 15 and 16 are provided with a low pressure pressure sensing part 22 and a high pressure pressure sensing part 23 for sensing the suction / discharge pressure of the compressors 15 and 16, respectively.

The accumulator 14 is a common accumulator connected to two compressors 15 and 16 for common use.

In addition, each of the main outdoor unit (M) and the sub outdoor unit (S1) (S2), the outdoor unit pipe temperature sensor 40 for sensing the temperature in the pipe between the indoor heat exchanger (2) and the outdoor electromagnetic expansion valve (18), respectively. More included.

The main outdoor unit M and the sub outdoor units S1 and S2 are respectively provided with an oil separator 30 and a capillary tube 32 provided on the suction side of the compressors 15 and 16, A supercooling device 34 for cooling the refrigerant transferred to the heat exchanger 2 and a liquid injection device 36 for lowering the temperature of the compressors 15 and 16 are further included.

Meanwhile, the refrigerant pipe (P) is provided with a dryer (38) for removing moisture inside the refrigerant pipe (P).

Looking at the operation of the air conditioner according to the present invention configured as described above with reference to Figures 1 to 4 as follows. The flow of the refrigerant during the cooling operation of the air conditioner according to the present invention is shown by the arrows shown in FIG.

When any one of the plurality of indoor units I requests a cooling operation, the indoor unit I and the outdoor units M, S1 and S2 which have requested the cooling operation are driven. The refrigerant is then compressed in the compressors (15) and (16), and the refrigerant compressed in the compressors (15) and (16) is a four-way valve (17), an outdoor heat exchanger (10), and an outdoor electromagnetic expansion valve (18). And, after passing through the indoor electromagnetic expansion valve (6) and the indoor heat exchanger (2) in turn, are circulated to the compressors (15) and (16) through the four-way valve (17). Of course, the refrigerant is circulated only to the indoor unit (I) and the outdoor unit (M) (S1) (S2) requesting the cooling operation. As described above, when the refrigerant is circulated along the refrigerant pipe P, the refrigerant deprives the indoor air heat of the room in which the indoor unit I is installed from the indoor heat exchanger 2, thereby providing a room in which the indoor unit I is installed. Is cooled.

At this time, the indoor electromagnetic expansion valve (6) is controlled according to the suction superheat degree or the discharge superheat degree. The outdoor expansion valve (18) is fully opened so that the refrigerant passes through the outdoor expansion valve (18) but is not expanded.

The operation of the air conditioner according to the present invention in the heating operation will now be described. The flow of the refrigerant in the heating operation of the air conditioner according to the present invention is opposite to the arrow shown in Fig.

When any one of the plurality of indoor units I requests heating operation, the refrigerant compressed by the compressors 15 and 16 is a four-way valve 17, an indoor heat exchanger 2, and an indoor electromagnetic expansion valve ( 6), the outdoor electromagnetic expansion valve 18, and the outdoor heat exchanger 60 in turn, and then circulated to the compressors 15 and 16 through the four-way valve 17. Then, the refrigerant discharges heat from the indoor heat exchanger 2 to the indoor air of the room where the indoor unit I is installed, thereby heating the room where the indoor unit I is installed.

At this time, the indoor electronic expansion valve 6 is fully opened so that the refrigerant passes through the indoor electronic expansion valve 6 but is not inflated. The outdoor electromagnetic expansion valve 18 is controlled according to the outdoor electronic expansion valve control algorithm during the heating operation as follows.

Hereinafter, the outdoor electronic expansion valve control algorithm during the heating operation will be described in detail.

First, when the operation of the air conditioner starts, it is first determined whether the cooling operation or heating operation (S10: first step). Whether the cooling and heating operation may be recognized through an operation such as an operation selection switch of the air conditioner, may be recognized according to a set room temperature, or may be determined through various methods.

As a result of the cooling and heating operation determination, when it is determined that the cooling operation is performed, the outdoor electromagnetic expansion valve 18 is completely opened as described in the operation of the air conditioner during cooling operation (S12).

On the other hand, when it is determined that the heating and heating operation is determined as the heating operation, it is first determined whether the outdoor electromagnetic expansion valve 18 can be normally controlled according to the suction superheat degree (S20: second step).

That is, since there is a limit to the amount of refrigerant that can be condensed in the indoor heat exchanger (2) acting as the condenser during heating operation, if the amount of refrigerant is excessive, the refrigerant is not sufficiently condensed in the indoor heat exchanger (2) and the two-phase saturated refrigerant It discharges from the said indoor heat exchanger 2 in a state. The saturated refrigerant in the two phases has a lower pressure drop in the pipe than the supercooled refrigerant sufficiently condensed in the indoor heat exchanger 2, and is discharged from the indoor heat exchanger 2 to reach the outdoor electromagnetic expansion valve 18. In this case, the state of the refrigerant becomes an ideal refrigerant having a significantly higher dryness, and the temperature also decreases considerably. Here, the limit of condensation of the indoor heat exchanger 2 acting as the condenser varies not only with the capacity of the indoor heat exchanger 2 itself, but also with various factors such as the current indoor temperature, the target indoor temperature difference, and the outdoor temperature.

Therefore, whether or not the suction overheating degree of the outdoor electromagnetic expansion valve 18 is normally controlled is determined by the condensation temperature of the refrigerant in the indoor heat exchanger 2 (hereinafter referred to as condensation temperature) and the outdoor unit piping temperature sensor 40. By comparing the sensed pipe temperature, that is, the liquid pipe temperature (hereinafter, referred to as liquid pipe temperature) of the refrigerant.

That is, as described above, when the amount of refrigerant exceeds the limit that can be accommodated by the indoor heat exchanger 2, the difference between the condensation temperature and the liquid pipe temperature is considerably large, and the value obtained by subtracting the liquid pipe temperature from the condensation temperature is a predetermined suction superheat degree. It may be determined whether or not the suction overheat of the outdoor electromagnetic expansion valve 18 is normally controlled by whether the normal control determination reference value A (hereinafter, referred to as a determination reference value) is exceeded. Here, the determination reference value A may be set by a test value, for example, may be set to 10 ± 2 ℃.

As a result of determining whether or not the intake superheat of the outdoor electromagnetic expansion valve 18 is normally controlled, if the value obtained by subtracting the liquid pipe temperature from the condensation temperature does not exceed the determination reference value A, an indoor heat exchanger in which the refrigerant acts as the condenser It is recognized that the state can be sufficiently condensed in the apparatus 2, and it is determined that the outdoor electromagnetic expansion valve 18 can be normally controlled by the suction superheat degree.

If it is determined that the outdoor electromagnetic expansion valve 6 can be normally controlled by the suction superheat degree, the outdoor electromagnetic expansion valve 18 is controlled to maintain the suction superheat degree constant (S22: third). step).

That is, if the suction superheat degree acquired in the operation state of the current air conditioner, that is, the current suction superheat degree is lower than the target suction superheat degree, the outdoor electromagnetic expansion valve 18 is the open state of the current outdoor electromagnetic expansion valve 18. It is controlled to close more. In other words, the opening value of the outdoor electromagnetic expansion valve 18 becomes small. Then, the flow rate of the refrigerant is reduced to increase the current suction superheat degree to match the target suction superheat degree.

Conversely, if the current suction superheat is higher than the target suction superheat, the outdoor electromagnetic expansion valve 18 is controlled to open above the current open state of the outdoor electromagnetic expansion valve 18. In other words, the opening value of the outdoor electromagnetic expansion valve 18 is increased. Then, the flow rate of the refrigerant is increased to reduce the current suction superheat degree to match the target suction superheat degree.

On the other hand, when the suction overheat of the outdoor electromagnetic expansion valve 18 is determined to be in normal control, if the value obtained by subtracting the liquid pipe temperature from the condensation temperature exceeds the determination threshold value A, the indoor heat exchanger in which the refrigerant amount acts as the condenser It is recognized that the limit that can be afforded by the instrument 2 is exceeded, and the outdoor electromagnetic expansion valve 18 is determined to be unable to be normally controlled by the suction superheat, and is supplemented and controlled as follows.

If it is determined that the outdoor electromagnetic expansion valve 18 cannot be normally controlled by the suction superheat degree, the outdoor electromagnetic expansion valve 18 is the current outdoor electron even if the current suction superheat degree is greater than the target suction superheat degree. The opening of the expansion valve 18 is controlled to be closed rather than the open state. That is, the opening value of the outdoor electromagnetic expansion valve 18 is reduced. At this time, the opening value of the outdoor electromagnetic expansion valve 18 may be reduced by a certain ratio (for example, 5%) as in the present embodiment. When it is determined that the outdoor electromagnetic expansion valve 18 cannot be normally controlled by the suction superheat degree, the outdoor electromagnetic expansion valve 18 may be decreased by a predetermined value other than the present embodiment, and is reduced in proportion to the difference between the condensation temperature and the liquid pipe temperature. It is also possible (S24).

In this way, even if the current suction superheat degree during the heating operation is greater than the target suction superheat degree, if the outdoor electromagnetic expansion valve 18 is controlled to be closed, the amount of refrigerant circulation is reduced and the supercooling of the indoor heat exchanger 2 acting as the condenser is performed. As the degree is increased again, the liquid refrigerant in the refrigerant that has undergone the evaporation process can be significantly reduced, so that a sudden increase in the amount of the liquid refrigerant stored in the accumulator 14 can be prevented.
Such a control process may be continuously circulated depending on whether the heating of the air conditioner is in operation (S26: fourth step).

As described above, the air conditioner and the control method thereof according to the present invention are not limited to the above embodiments, and may be variously implemented within the technical scope to which the present invention belongs. That is, even during the cooling operation, the indoor electromagnetic expansion valve 6 may be controlled like the outdoor electromagnetic expansion valve 18 described above. In this case, in addition to the multi-type heat pump type, which is the above-described embodiment, a multi-type dedicated for cooling / heating is also possible, and a single type for cooling / heating is also possible, and is applicable to a single type heat pump type.

As described above, the air conditioner and the control method thereof according to the present invention may be controlled according to the suction superheat degree of the outdoor electronic expansion valve or the outdoor superheat expansion valve according to the difference between the condensation temperature and the liquid pipe temperature during the heating operation. It can be controlled to close irrespective of the amount, which can prevent a sudden decrease in the amount of refrigerant that can be circulated, so that the system can always be stabilized in response to various operating conditions, and the performance is improved as well as the sensitivity quality related to system responsiveness. There is an advantage that can be.

Claims (9)

And if the difference between the condensation temperature and the liquid pipe temperature is within the preset value, the expansion valve is controlled according to the suction superheat, and otherwise the opening amount of the expansion valve is reduced so that the opening value of the expansion valve is reduced. The method according to claim 1, If the difference between the condensation temperature and the liquid pipe temperature is not within a predetermined value, the opening amount of the expansion valve is reduced by a certain ratio. The method according to claim 1 or 2, The control method of the air conditioner is a control method of the air conditioner performed during the heating operation during the cooling, heating operation. A compressor through which the refrigerant is circulated, a condenser, an expansion valve, and an evaporator; The expansion valve is controlled according to the suction superheat if the difference between the condensation temperature and the liquid pipe temperature measured in the condenser is within a preset value, otherwise the opening amount of the expansion valve is reduced so that the opening value of the expansion valve is reduced. Air conditioner with unit. A first step of determining whether a cooling operation or a heating operation is performed when the operation of the air conditioner starts; According to the first step, if the cooling operation is determined to open the outdoor electronic expansion valve completely, if the heating operation is determined to determine whether the outdoor electronic expansion valve is a situation that can be normally controlled according to the suction superheat degree Steps; In the second step, when it is determined that the outdoor electromagnetic expansion valve can be normally controlled, the suction superheat is controlled to be kept constant, and when it is determined that the outdoor electromagnetic expansion valve cannot be normally controlled, the outdoor electronic And a third step of controlling the opening degree of the expansion valve to be reduced. The method of claim 5, And a fourth step of continuously circulating the control process of the first to third steps when the air conditioner is being heated. An indoor heat exchanger for a cooling and heating operation, a compressor, an expansion valve, an outdoor heat exchanger, a four-way valve, an indoor electromagnetic expansion valve, and an outdoor electromagnetic expansion valve; The outdoor electromagnetic expansion valve is fully opened in the cooling operation, and in the heating operation, when the condensation temperature and the liquid pipe temperature are within the preset values, the expansion valve is controlled according to the suction superheat, otherwise the opening amount of the expansion valve is reduced. An air conditioner having a control unit. The method according to claim 4 or 7, And the condensation temperature is obtained by an indoor heat exchanger temperature sensor located in the indoor heat exchanger. The method according to claim 4 or 7, And the liquid pipe temperature is obtained by an outdoor unit pipe temperature sensor located at an inlet side of the outdoor electromagnetic expansion valve.

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