KR20190005445A - Method for controlling multi-type air conditioner - Google Patents

Abstract

A method of controlling a multi-type air conditioner according to the present invention includes the steps of: performing a cooling operation (S110); determining whether an entry condition is satisfied by determining the outside temperature, a compressor operating frequency, and an indoor pipe temperature during the cooling operation (S120); determining the piping temperature level when the entry condition (S120) is satisfied (S130); controlling a supercooling unit in accordance with the pipe temperature level determined in step S130, bypassing a part of refrigerant, which flows through a liquid pipe from an outdoor heat exchanger to an indoor unit when controlling the supercooling unit, to one of an accumulator or a compressor through a supercooling bypass pipe, and adjusting the opening value of a supercooling expansion valve disposed in the supercooling bypass pipe (S140); and determining a release condition after step S140 (S150), wherein the process returns to step S110 when the release condition of step S150 is satisfied, and the process returns to step S120 when the release condition of step S150 is not satisfied. The multi-type air conditioner according to the present invention can perform continuous driving at a low load while suppressing freezing of an indoor heat exchanger even in a cooling low load state.

Description

[0001] The present invention relates to a multi-type air conditioner,

The present invention relates to a control method of a multi-type air conditioner, and more particularly, to a control method of a multi-type air conditioner that can prevent a compressor from being turned off when a low-load cooling operation is performed.

The air conditioner is a device for cooling / heating the room or purifying the room air to create a more comfortable indoor environment for the user.

In recent years, the development of a multi-type air conditioner for cooling or heating each room in order to more efficiently cool or heat an indoor space divided into a plurality of rooms has been continuously carried out.

In such a multi-type air conditioner, a plurality of indoor units are connected to one outdoor unit, at least one indoor unit is installed in each room, and the indoor unit operates in one of heating and cooling modes to air condition the room.

The multi-type air conditioner may include a distributor for connecting the outdoor unit and the indoor unit. The distributor connects the refrigerant pipe to the indoor unit to send the gas refrigerant to the indoor unit or to send the liquid refrigerant to the indoor unit.

In particular, when the number of indoor units is increased, a plurality of distributors can be arranged, and a plurality of distributors must be connected to each other.

However, in the conventional multi-type air conditioner, when the outside air temperature is low, when the compressor is driven by the low load cooling operation, there is a problem that the amount of circulation of the refrigerant is large and freezing occurs in the indoor heat exchanger and the compressor is turned off.

Korean Patent Publication No. 10-1996-0003489 A

An object of the present invention is to provide a control method of a multi-type air conditioner that can minimize the turn-off of a compressor when the cooling operation is performed at a low load.

The multi-type air conditioner according to the present invention minimizes the refrigerant flowing into the indoor heat exchanger when the low-load cooling operation is performed, thereby preventing freezing of the indoor heat exchanger and minimizing the compressor off.

A method of controlling a multi-type air conditioner according to the present invention includes steps (S110) of cooling operation; (S120) during the cooling operation by determining the outside temperature, the compressor operating frequency, and the indoor pipe temperature and determining whether the inlet condition is satisfied; Determining the piping temperature level when the entry condition (S120) is satisfied (S130); The control unit controls the supercooling unit in accordance with the pipe temperature level determined in step S130 and controls the supercooling unit so that a part of the refrigerant flowing into the indoor unit through the liquid pipe in the outdoor heat exchanger during the control of the supercooling unit is passed through the supercooling bypass pipe, Adjusting the opening value of the supercooling expansion valve disposed in the supercooling bypass pipe (S140); Determining a release condition after step S140 (S150); If the release condition of S150 is satisfied, the process returns to step S110. If the release condition of S150 is not satisfied, the process returns to step S120.

Wherein the entry condition comprises a first entry condition, a second entry condition, and a third entry condition, wherein the first entry condition determines whether the outside temperature is less than a reference outside temperature, and the second entry condition is an operation frequency The third entry condition may include determining whether the piping temperature of the indoor unit in operation is less than the target temperature.

The reference ambient temperature may be 0 degree Celsius.

In step S130, the high pressure level of the refrigerant is divided into a first temperature level, a second temperature level and a third temperature level. The first temperature level is " piping temperature ≥ 0 ℃, ≪ 0 ° C ", the second temperature level is " piping temperature < -4 DEG C ", and in the case of the first temperature level, the subcooling unit is controlled to be in the normal cooling operation, The opening value of the supercooling expansion valve is controlled by +10 pulses per 10 seconds, and in the case of the third temperature level, the opening value of the supercooling expansion valve is controlled by +20 pulses per 10 seconds.

A method of controlling a multi-type air conditioner according to the present invention includes steps (S110) of cooling operation; (S120) during the cooling operation by determining the outside temperature, the compressor operating frequency, and the indoor pipe temperature and determining whether the inlet condition is satisfied; Determining the piping temperature level when the entry condition (S120) is satisfied (S130); The control unit controls the supercooling unit in accordance with the pipe temperature level determined in step S130 and controls the supercooling unit so that a part of the refrigerant flowing into the indoor unit through the liquid pipe in the outdoor heat exchanger during the control of the supercooling unit is passed through the supercooling bypass pipe, Adjusting the opening value of the supercooling expansion valve disposed in the supercooling bypass pipe (S140); Determining a release condition after step S140 (S150); If it is determined that the release condition of S150 is satisfied, the process returns to step S110, and if the release condition of S150 is not satisfied, determining (S160) a compressor off condition; If the step S160 is not satisfied, the process returns to step S120. If the step S160 is satisfied, the step S170 turns off the compressor.

Wherein the entry condition comprises a first entry condition, a second entry condition, and a third entry condition, wherein the first entry condition determines whether the outside temperature is less than a reference outside temperature, and the second entry condition is an operation frequency The third entry condition may include determining whether the piping temperature of the indoor unit in operation is less than the target temperature.

The multi-type air conditioner of the present invention has one or more of the following effects.

First, the multi-type air conditioner according to the present invention can continuously operate without turning off the compressor in a cooling low load state.

Second, the multi-type air conditioner according to the present invention has an advantage that it can minimize the operation stop due to the cooling low load, thereby satisfying the cooling need of the consumer.

Third, the multi-type air conditioner according to the present invention is advantageous in that continuous operation can be performed at a low load while suppressing freezing of the indoor heat exchanger even in a cooling low load.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description of the claims.

1 is a configuration diagram of a multi-type air conditioner according to a first embodiment of the present invention.
FIG. 2 is an exemplary view showing a refrigerant flow during heating operation in the multi-type air conditioner shown in FIG. 1. FIG.
3 is a flowchart showing a control method for continuous operation of low load heating in the multi-type air conditioner according to the first embodiment of the present invention.
FIG. 4 is an exemplary view showing a refrigerant flow during a cooling operation in the multi-type air conditioner shown in FIG. 1. FIG.
FIG. 5 is an exemplary view showing a refrigerant flow in a low-load cooling operation in the multi-type air conditioner shown in FIG.
FIG. 6 is a flowchart showing a control method for a low load cooling continuous operation in the multi-type air conditioner according to the first embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

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

FIG. 1 is a configuration diagram of a multi-type air conditioner according to a first embodiment of the present invention, FIG. 2 is an exemplary view showing a refrigerant flow during a heating operation in the multi-type air conditioner shown in FIG. 1, FIG. 4 is a flowchart showing a control method for a low load heating continuous operation in the multi-type air conditioner according to the first embodiment of the present invention. FIG. 5 is an exemplary view showing a refrigerant flow in a low-load cooling operation in the multi-type air conditioner shown in FIG. 1, and FIG. 6 is a view showing an example of a multi- A control method for continuous operation of load cooling is shown in the flowchart.

The multi-type air conditioner according to the present invention includes an outdoor unit (A) and an indoor unit (D).

In the case of the indoor unit (D), it can be operated by cooling or heating. A plurality of indoor units (C1, C2, C3) may be disposed in the indoor unit (D).

Each indoor unit (C1, C2, C3) includes an indoor heat exchanger, an indoor expansion valve, and an indoor ventilation fan.

The outdoor unit A or the indoor unit D is provided with a variety of structures such as a pressure switch, a pressure sensor, a temperature sensor, a check valve, a strainer, etc., which are well known to those skilled in the art.

<Configuration of outdoor unit>

The outdoor unit A includes an outdoor unit case (not shown) and a compressor 10 disposed therein, and an outdoor heat exchanger 20, an accumulator 30, a four-way valve 40, an oil separator 50, An expansion valve 70, a hot gas unit 90, and a supercooling unit 100.

The outdoor unit case includes a gas piping service valve 13 to which a gas piping 82 is connected and a liquid piping service valve 14 to which a liquid piping 12 is connected.

The gas piping service valve 13 and the liquid piping service valve 14 are connected to the indoor unit D through a refrigerant pipe and circulate the refrigerant in the outdoor unit A. [

The compressor (10) uses an inverter compressor capable of controlling the amount of refrigerant and the discharge pressure of the refrigerant by adjusting the operation frequency.

The outdoor heat exchanger (20) is a device for exchanging heat between outdoor air and refrigerant. In this embodiment, a plurality of the outdoor heat exchangers 20 may be provided. The outdoor heat exchanger (20) is operated as a condenser during cooling operation and as an evaporator during heating operation.

In this embodiment, the outdoor heat exchanger 20 is constituted by a first outdoor heat exchanger 22 and a second outdoor heat exchanger 24.

An outdoor blowing fan (60) is disposed to improve the heat exchange of the outdoor heat exchanger (20).

The accumulator (30) provides the refrigerant to the compressor (10). The accumulator 30 is disposed on the suction side of the compressor 10 and is connected to the four-way valve 40.

<Configuration of four-way valve>

The four-way valve 40 includes a first flow path 41, a second flow path 42, a third flow path 43, and a fourth flow path 44.

The first flow path (41) is connected to the discharge side of the compressor (10). A pipe connecting the first flow path (41) and the discharge side of the compressor (10) is defined as a four-way valve-compressor connecting pipe (81).

The second flow path 42 is connected to the gas piping 82. A pipe connecting the second flow path (42) and the gas piping service valve (13) is defined as the gas piping (82).

The third flow path (43) is connected to the outdoor heat exchanger (20). A pipe connecting the third flow path 43 and the outdoor heat exchanger 20 is defined as a four-way valve-outdoor heat exchanger connecting pipe 83.

Since two outdoor heat exchangers 20 are provided, two of the four-way valve-outdoor heat exchanger connecting pipes 83 are disposed.

The four-way valve-outdoor heat exchanger connecting pipe 83 includes a first four-way valve-outdoor heat exchanger connecting pipe 83a connecting the first outdoor heat exchanger 22 and the four-way valve 40 (third flow path) . The four-way valve-outdoor heat exchanger connecting pipe 83 includes a four-way valve-outdoor heat exchanger connecting pipe 83b connecting the second outdoor heat exchanger 24 and the four-way valve 40 (third flow path).

The first four-way valve-outdoor heat exchanger connecting pipe 83a and the second four-way valve-outdoor heat exchanger connecting pipe 83b are joined together and connected to the third flow path 43.

The fourth flow path (44) is connected to the accumulator (30). A pipe connecting the fourth flow path (44) and the accumulator (30) is defined as a four-way valve-accumulator connecting pipe (84).

<Configuration of Oil Separator>

The oil separator 50 is disposed on the discharge side of the compressor 10 and the refrigerant discharged to the compressor 10 flows to the four-way valve 40 through the oil separator 50.

The oil separator 50 recovers the oil contained in the discharged refrigerant and provides it to the compressor 10 again.

The oil separator 50 includes an oil return pipe 51 for guiding oil to the compressor 10 and a check valve 52 disposed in the oil return pipe 51 for allowing the refrigerant to flow in one direction .

The oil separator (50) is installed in the four-way valve-compressor connecting pipe (81).

The accumulator (30) is also provided with an oil recovery structure capable of recovering oil by the compressor (10). An oil return pipe 31 connecting the lower side of the accumulator 30 and the suction side pipe 35 of the compressor and an oil return valve 32 disposed in the oil return pipe 31 for controlling the flow of oil .

&Lt; Configuration of Outdoor Expansion Valve >

The outdoor expansion valve (70) expands the refrigerant flowing to the outdoor heat exchanger (20) during the heating operation. During the cooling operation, the outdoor expansion valve (70) passes the refrigerant without expanding it. The outdoor expansion valve (70) may be an electronic expansion valve capable of adjusting an opening value according to an inputted signal.

The outdoor expansion valve (70) includes a first outdoor expansion valve (72) for expanding the refrigerant flowing into the first outdoor heat exchanger (72), a second outdoor expansion valve And a second outdoor expansion valve (74).

The first outdoor expansion valve (72) and the second outdoor expansion valve (74) are connected to the liquid pipe (12). During the heating operation, the refrigerant condensed in the indoor unit (D) is supplied to the first outdoor expansion valve (72) and the second outdoor expansion valve (74).

The liquid pipe 12 is branched and connected to the first outdoor expansion valve 72 and the second outdoor expansion valve 74 to be connected to the first outdoor expansion valve 72 and the second outdoor expansion valve 74, Respectively. The first outdoor expansion valve (72) and the second outdoor expansion valve (74) are arranged in parallel.

A pipe connecting the first outdoor expansion valve (72) and the first outdoor heat exchanger (22) is defined as a first outdoor heat exchanger pipe (23).

And a pipe connecting the second outdoor expansion valve (74) and the second outdoor heat exchanger (24) are defined as the second outdoor heat exchanger pipe (25).

&Lt; Configuration of Hot Gas Unit >

In this embodiment, a hot gas unit 90 for bypassing the refrigerant supplied to the outdoor heat exchanger 20 to the indoor unit D is disposed during the heating operation.

The hot gas unit 90 includes a hot gas bypass piping and a hot gas valve for bypassing the refrigerant.

In this embodiment, a first hot gas bypass pipe 91 connecting the first outdoor heat exchanger pipe 23 and the four-way valve-compressor connection pipe 81 is disposed.

One end of the first hot gas bypass pipe 91 is connected to the first outdoor heat exchanger pipe 23 and the other end is connected to the four-way valve-compressor connecting pipe 81.

A second hot gas bypass pipe 92 for connecting the second outdoor heat exchanger pipe 25 and the four-way valve-compressor connection pipe 81 is disposed.

One end of the second hot gas bypass pipe 92 is connected to the first outdoor heat exchanger pipe 23 and the other end is connected to the four-way valve-compressor connecting pipe 81.

A first hot gas valve 93 is disposed in the first hot gas bypass pipe 91 and a second hot gas valve 94 is disposed in the second hot gas bypass pipe 92.

As the hot gas valve, a solenoid valve capable of adjusting the opening amount is used, and an opening / closing valve may be used.

The first hot gas bypass piping 91 and the second hot gas bypass piping 92 may be connected to the four-way valve-compressor connecting piping 81, respectively. In this embodiment, however, Is connected to the four-way valve-compressor connecting pipe (81).

A three-way valve may be used to join the first hot gas bypass line 91 and the second hot gas bypass line 92 together.

The first hot gas valve 93 or the second hot gas valve 94 may be selectively activated. For example, only the first hot gas valve 93 may be opened or closed, or only the second hot gas valve 94 may be opened or closed.

Further, a variable path pipe 85 for connecting the first outdoor heat exchanger pipe 23 and the second four-way valve-outdoor heat exchanger connecting pipe 83b is further disposed, and the variable path pipe 84 is provided with a variable path A valve 86 may be further disposed.

The variable path valve 86 can be selectively operated. When the variable path valve 86 is opened, the refrigerant flowing along the first outdoor heat exchanger pipe 23 passes through the variable path pipe 85 and the variable path valve 86, 40 to the third flow path 43 of the second flow path.

When the variable path valve 86 is closed, the refrigerant supplied through the first outdoor heat exchanger pipe 23 flows into the first outdoor heat exchanger 22 during the heating operation.

When the variable path valve 86 is closed, the refrigerant that has passed through the first outdoor heat exchanger 22 flows into the liquid pipe 12 through the first outdoor heat exchanger pipe 23 during the cooling operation.

A check valve 87 is disposed in the second four-way valve-outdoor heat exchanger connecting pipe 83b and the check valve 87 is opened so that the refrigerant supplied from the third flow path 43 flows into the second four- Exchanger connecting pipe 83b.

And an expansion valve bypass pipe 88 connecting the front end and the rear end of the second outdoor expansion valve 74 are disposed. One end and the other end of the expansion valve bypass pipe (88) are connected to the second outdoor heat exchanger pipe (25).

A check valve 89 is also disposed in the expansion valve bypass pipe 88. The check valve 89 is configured to pass the refrigerant flowing from the second outdoor heat exchanger pipe 25 to the liquid pipe 12 during the cooling operation. During the heating operation, the refrigerant flow in the opposite direction is blocked.

<Configuration of the supercooling unit>

The supercooling unit 100 may further be disposed in the liquid pipe 12. [

The supercooling unit 100 includes a supercooling heat exchanger 101, a supercooling bypass pipe 102 bypassed from the liquid pipe 12 and connected to the supercooling heat exchanger 101, A first supercooling expansion valve 103 for selectively expanding the refrigerant flowing in the supercooling heat exchanger 102 and a supercooling-compressor connecting pipe 104 for connecting the supercooling heat exchanger 101 and the compressor 10, And a second supercooling expansion valve 105 disposed in the supercooling-compressor connecting pipe 104 for selectively expanding the refrigerant flowing therethrough.

The supercooling unit 100 may further include an accumulator bypass pipe 106 connecting the accumulator 30 and the subcooling-compressor connecting pipe 104. The accumulator bypass pipe 106 is connected to the accumulator 30, To the second subcooling expansion valve (105).

The accumulator bypass pipe 106 is further provided with a supercooling bypass valve 107.

The first supercooling expansion valve 103 expands the liquid refrigerant to provide it to the supercooling heat exchanger 101. The expanded refrigerant evaporates in the supercooling heat exchanger 101 to cool the supercooling heat exchanger 101 . The liquid refrigerant flowing into the outdoor heat exchanger (20) through the liquid pipe (12) can be cooled while passing through the supercooling heat exchanger (101). The first subcooling expansion valve 103 may be selectively operated to control the temperature of the liquid refrigerant.

During operation of the first subcooling expansion valve 103, the second subcooling expansion valve 105 opens and the refrigerant flows to the compressor 10.

A temperature sensor is disposed on the inlet side and the outlet side of the supercooling heat exchanger (101), respectively, and senses the temperature of the refrigerant passing through the temperature sensor.

The supercooling bypass valve 107 is selectively operated to provide the liquid refrigerant of the accumulator 30 to the second subcooling expansion valve 105.

The second subcooling expansion valve 105 is selectively operated to expand the refrigerant to lower the temperature of the refrigerant supplied to the compressor 10. When the compressor (10) exceeds the normal operating temperature range, the refrigerant expanded in the second subcooling expansion valve (105) can be evaporated in the compressor (10) and the temperature of the compressor Can be lowered.

<Configuration of Receiver Unit>

The liquid pipe (12) may further include a receiver unit (110).

The receiver 110 may store the liquid refrigerant to regulate the amount of circulating refrigerant. The receiver 110 stores the liquid refrigerant in the accumulator 30 and stores the liquid refrigerant separately.

The receiver (110) supplies refrigerant to the accumulator (30) when the amount of circulating refrigerant is insufficient, and when the amount of circulating refrigerant is large, the refrigerant is recovered and stored.

A pipe connecting the outdoor expansion valves (72) (74) and the supercooling heat exchanger (101) among the liquid pipes (12) is defined as a supercooled liquid pipe (12 ').

The receiver 110 includes a receiver tank 111 for storing refrigerant, a first receiver connection pipe 112 for connecting the receiver tank 111 and the supercooling liquid pipe 12 ' A second receiver connection pipe 114 connecting the first receiver connection pipe 112 and the accumulator 30 and a first receiver valve 113 disposed in the first receiver connection pipe 112 for interrupting the flow of the refrigerant, And a second receiver valve 115 disposed in the pipe 114 for controlling the flow of the refrigerant.

The controller of the multi-type air conditioner controls the first receiver valve 113 and the second receiver valve 115 to regulate the amount of refrigerant circulated.

<Heating operation>

The refrigerant flow in the heating operation of the multi-type air conditioner according to the present embodiment will be described in more detail with reference to FIG.

During the heating operation, the refrigerant compressed in the compressor (10) flows to the first flow path (41) of the four-way valve (40) through the oil separator (50).

The control unit controls the refrigerant flowing into the first flow path (41) of the four-way valve (40) to flow into the second flow path (42). The refrigerant discharged to the second flow path 42 is supplied to the indoor unit D through the gas piping 82. In the indoor unit (D), the supplied refrigerant is condensed and the room is heated through the heat released during the condensation of the refrigerant.

The condensed refrigerant is recovered into the liquid pipe (12).

The refrigerant flowing into the liquid pipe 12 is supplied to the outdoor expansion valve 70 after passing through the supercooling unit 100.

The first outdoor expansion valve (72) and the second outdoor expansion valve (74) expand the condensed refrigerant and then supply the expanded refrigerant to the outdoor heat exchanger (20).

The refrigerant expanded in the first outdoor expansion valve 72 is supplied to the first outdoor heat exchanger 22 and the refrigerant expanded in the second outdoor expansion valve 74 is supplied to the second outdoor heat exchanger 24 .

The first outdoor expansion valve (72) and the second outdoor expansion valve (74) evaporate the expanded refrigerant, and the evaporated refrigerant is combined and flows into the third flow path (43) of the four-way valve (40).

The refrigerant flowing into the third flow path 43 is supplied to the accumulator 30 through the fourth flow path 44.

The accumulator 30 stores the liquid refrigerant in the supplied refrigerant, and supplies only the gas refrigerant to the compressor 10.

During the normal heating operation, the first hot gas valve 93, the second hot gas valve 94 and the variable path valve 86 are turned off to maintain the closed state.

<Low-load heating operation>

A control method for continuous operation of the compressor in the heating low load state in the multi-type air conditioner according to the present embodiment will be described in more detail with reference to FIG.

In a case where the compressor 10 is continuously operated under the low load and the heating operation, the high pressure may rise even if the compressor 10 is operated at the minimum operating frequency. If the compressor 10 is operated at the minimum operating frequency and the high pressure rises, the compressor 10 must be turned off for a predetermined time and then restarted to protect the compressor 10. At this time, when the compressor 10 is turned off, since the refrigerant for heating is not supplied to the indoor unit D, the user can not cope with the flood load.

The present embodiment provides a control method capable of coping with a heating load by continuing operation without turning off the compressor 10 when several conditions are satisfied.

The control method of the multi-type air conditioner according to the present embodiment includes a step S10 of heating operation, a step S20 of determining whether the entering condition is satisfied during the heating operation, A step S40 of controlling the hot gas unit 90 according to the high pressure level determined at S30, a step S50 of determining a release condition after the step S40, (S60), when the release condition of S50 is satisfied, returning to step S10, and if the release condition of S50 is not satisfied, determining (S60) a compressor off condition , The operation returns to step S20 and turns off the compressor 10 when the compressor off condition of the step S60 is satisfied (step S70).

The control method according to the present embodiment is performed only during the heating operation. The outdoor unit is not controlled under the conditions such as the cooling operation or the dehumidification operation other than the heating operation, and the outdoor unit is controlled by the control method accordingly.

The entry condition S20 is composed of a first entry condition, a second entry condition, and a third entry condition.

The first entering condition is to judge whether the outside air temperature is equal to or higher than the reference outside air temperature (20 degrees Celsius in the present embodiment). The second entry condition is to determine if the operating frequency of the compressor 10 is the minimum operating frequency. The third entry condition is to judge whether the high pressure of the outdoor unit exceeds the target high pressure.

If the first entry condition, the second entry condition, and the third entry condition are all satisfied, the process proceeds to step S30.

The reference ambient temperature of the first entry condition may be changed according to the installation environment. However, when the outside temperature is 20 degrees or more, if the heating operation is performed, the heating load does not greatly increase. In consideration of this, the reference outside air temperature can be set.

The minimum operating frequency of the second entry condition may be different depending on the inverter compressor. The minimum operating frequency means a minimum operating condition that can be operated while preventing damage to the compressor. Generally, when the compressor is operated below the minimum operating frequency, oil is not sucked through the refrigerant and the compressor is damaged.

The high pressure of the third entry condition may be the discharge side refrigerant pressure of the compressor or the refrigerant pressure of the indoor unit operated by the condenser. In this embodiment, the high pressure is determined on the basis of the discharge side refrigerant pressure of the compressor.

The third entry condition determines whether the discharge side refrigerant pressure of the compressor exceeds a target high pressure. In the present embodiment, it is determined whether the refrigerant pressure is higher than the refrigerant pressure (target high pressure + excess pressure) of the outdoor unit, thereby improving reliability. The excess high pressure is 100 KPa in this embodiment.

In step S30, the high pressure level of the refrigerant is determined. The step S30 may be calculated together with the determination of the third entry condition of step S20.

In step S30, it is determined how high the pressure of the refrigerant is, and control is performed accordingly.

In step S30, the high pressure of the refrigerant is divided into three.

The first high pressure level is "refrigerant high pressure ≥ target high pressure + excess pressure * 1.5 (150 KPa in this embodiment)".

The second high pressure level is "target high pressure + excess pressure <refrigerant high pressure <target high pressure + excess pressure 1.5 (150 KPa in this embodiment)".

The third high pressure level is " refrigerant high pressure &lt; target high pressure + excess pressure &quot;.

In step S40, the hot gas unit 90 is controlled differently according to the high pressure level.

In the case of the first high pressure level, the hot gas valve is turned on to cause the expanded refrigerant to flow to the indoor unit (D).

In the case of the second high pressure level, the hot gas valve is maintained in its current state.

When the hot gas valve is in an ON state, the hot gas valve remains in an ON state. When the hot gas valve is in an OFF state, the hot gas valve remains in an OFF state.

In the case of the third high pressure level, the hot gas valve is turned off.

Since the hot gas valve is controlled to be turned on or off in step S30, the refrigerant expanded toward the indoor unit (D) can be sent to lower the high pressure of the indoor unit (D).

In step S40, at least one of the first hot gas valve 93 and the second hot gas valve 94 may be on / off-controlled.

In this embodiment, only the first hot gas valve 93 is controlled to be ON / OFF, and the second outdoor heat exchanger 22 is normally operated. When the first hot gas valve 93 is controlled to be on / off controlled, the performance of the evaporator during the heating operation of the first outdoor heat exchanger 24 is lowered.

In step S50, a release condition for terminating the control of the hot gas unit 90 is determined. The releasing condition S50 is constituted by a first releasing condition, a second releasing condition and a third releasing condition.

The first release condition judges whether or not a non-heating operation is inputted.

The second release condition determines whether the outside air temperature is lower than the reference outside air temperature.

The third release condition determines whether the compressor 10 exceeds the minimum operating frequency.

When at least one of the first release condition, the second release condition, or the third release condition is satisfied, the control of the hot gas unit 90 is terminated.

After the step S50, the compressor off condition is determined in step S60.

The compressor off condition determines whether the high pressure of the refrigerant continues to rise despite the control of the hot gas unit 90 in step S40.

In addition, the compressor off condition may be when the discharge temperature of the compressor rises above the maximum temperature. The compressor off condition is for protecting the compressor.

If the compressor off condition is satisfied, the compressor is turned off in step S70.

If the compressor off condition is not satisfied, the process returns to step S20 to determine the entry condition again, and repeats the following steps.

In the case of controlling the multi-type air conditioner as in the present embodiment, continuous operation can be performed without turning off the compressor in the case of heating low load.

In the case of controlling the multi-type air conditioner as in the present embodiment, the operation stop due to the heating low load can be minimized, thereby satisfying the heating needs of the consumer.

In the case of controlling the multi-type air conditioner as in the present embodiment, continuous operation can be performed at a low load while suppressing the rise of the high pressure even in the case of the heating low load.

<Cooling operation>

Referring to FIG. 4, the refrigerant flow during the cooling operation of the multi-type air conditioner according to the present embodiment will be described in more detail.

The refrigerant compressed by the compressor 10 flows into the first flow path 41 of the four-way valve 40 through the oil separator 50. [

The control unit controls the refrigerant flowing into the first flow path 41 of the four-way valve 40 to flow into the third flow path 43. The refrigerant flowing to the third flow path (43) flows to the outdoor heat exchanger (20).

The refrigerant is supplied to the first outdoor heat exchanger 22 through the first four-way valve-outdoor heat exchanger connecting pipe 83a and is supplied to the second outdoor heat exchanger (not shown) through the second four-way valve-outdoor heat exchanger connecting pipe 83b 24.

The refrigerant heat-exchanged in the first outdoor heat exchanger (22) and the second outdoor heat exchanger (24) is supplied to the indoor unit (D) through the liquid pipe (12).

The indoor heat exchanger of the indoor unit (D) evaporates the supplied refrigerant to cool the room, and the evaporated refrigerant is recovered to the outdoor unit through the gas pipe (82).

The evaporated refrigerant is recovered through the second flow path 42 of the four-way valve 40 and the control unit connects the second flow path 42 and the fourth flow path 44 to the accumulator 30 Flow. The accumulator 30 stores the liquid refrigerant in the recovered refrigerant, and supplies the gas refrigerant to the compressor 10.

<Cooling continuous operation at low load>

When the refrigeration is operated at a low load, the compressor 10 can be operated at the minimum operating frequency. Even if the compressor is operated at the minimum operating frequency, if there is a large amount of refrigerant supplied to the indoor unit, freezing may occur in the indoor heat exchanger. In order to prevent this, the controller may turn off the compressor. When the compressor 10 is turned off, there is a problem in that it takes time to restart the compressor and the compressor can not respond immediately when the cooling load is increased.

For this purpose, in this embodiment, the supercooling unit 100 is used to carry out low load cooling succession.

During the low-load cooling operation, the refrigerant compressed in the compressor 10 flows into the first flow path 41 of the four-way valve 40 through the oil separator 50.

The control unit controls the refrigerant flowing into the first flow path 41 of the four-way valve 40 to flow into the third flow path 43. The refrigerant flowing to the third flow path (43) flows to the outdoor heat exchanger (20).

The refrigerant is supplied to the first outdoor heat exchanger 22 through the first four-way valve-outdoor heat exchanger connecting pipe 83a and is supplied to the second outdoor heat exchanger (not shown) through the second four-way valve-outdoor heat exchanger connecting pipe 83b 24.

Alternatively, the variable path valve 86 may be turned off (closed) to allow the refrigerant to flow only through the second outdoor heat exchanger 24.

The first outdoor expansion valve (72) disposed in the first outdoor heat exchanger pipe (23) can maintain the fully opened state and can pass the condensed refrigerant. The second outdoor expansion valve (74) disposed in the second outdoor heat exchanger pipe (25) is also kept in the fully opened state and can pass the condensed refrigerant.

The first hot gas valve 93 and the second hot gas valve 94 are controlled to be turned off (closed state).

The refrigerant condensed in the outdoor heat exchanger (20) is supplied to the indoor unit (D) through the liquid pipe (12).

Here, the control unit controls the subcooling unit 100 to reduce the amount of refrigerant supplied to the indoor unit D. The subcooler unit 100 is controlled to form or maintain the pressure or temperature of the refrigerant during normal cooling operation.

The opening value is made larger in the low-load cooling operation than in the normal case, thereby reducing the amount of the refrigerant supplied to the indoor unit (D). The refrigerant bypassed by the subcooling unit 100 may be flowed to the accumulator 30 or the compressor 10.

In the low-load cooling operation, a part of the refrigerant that has passed through the supercooling heat exchanger (101) is bypassed by the supercooling bypass pipe (102).

The refrigerant bypassed in the supercooling bypass pipe 102 may be supplied to the accumulator 30 through the accumulator bypass pipe 106 and the supercooling bypass valve 107.

The refrigerant bypassed in the supercooling bypass pipe 102 may be supplied to the compressor 10 through the supercooling-compressor connecting pipe 104 and the second subcooling expansion valve 105.

The control unit may control the supercooling bypass valve 107 or the second subcooling expansion valve 105 to flow the bypassed refrigerant to the accumulator 30 or the compressor 10. [

During the low-load cooling operation, the first subcooling expansion valve 103 opens at a larger value than during normal cooling operation, thereby reducing the refrigerant supplied to the indoor unit (D).

The control method of the multi-type air conditioner according to the present embodiment for continuous heating operation under low load will be described in more detail with reference to FIG.

The control method of the multi-type air conditioner according to the present embodiment includes a step S110 of cooling operation, a step S120 of determining whether the entering condition is satisfied during the cooling operation, and a step S120 when the entering condition S120 is satisfied. (S140) of determining the temperature level of the indoor unit piping (S130), controlling the opening value of the first subcooling expansion valve (103) according to the piping temperature level determined in S30 (S140) (S160) of determining whether or not the compressor off condition is satisfied when the release condition of S150 is satisfied; and if the release condition of S150 is satisfied, If the condition is not satisfied, the operation returns to step S120, and if the compressor off condition of S160 is satisfied, the step of turning off the compressor 10 (step S170).

The entering condition S120 is composed of a first entering condition, a second entering condition, and a third entering condition.

The first entry condition is to judge whether the outside air temperature is less than the reference outside temperature (zero degree in the present embodiment). The second entry condition is to determine if the operating frequency of the compressor 10 is the minimum operating frequency. The third entering condition is to determine whether the piping temperature of the indoor unit is less than the target temperature (0 deg. C in the present embodiment).

If the first entry condition, the second entry condition, and the third entry condition are all satisfied, the process proceeds to step S130 or step S140.

The reference ambient temperature of the first entry condition may be changed according to the installation environment.

The minimum operating frequency of the second entry condition may be different depending on the inverter compressor. The minimum operating frequency means a minimum operating condition that can be operated while preventing damage to the compressor. Generally, when the compressor is operated below the minimum operating frequency, oil is not sucked through the refrigerant and the compressor is damaged.

The indoor unit pipe temperature of the third entry condition can be sensed through a temperature sensor installed in the vicinity of the indoor heat exchanger of the indoor unit in operation. And the third entry condition satisfies the condition that the piping temperature of the indoor heat exchanger in operation is 0 degree Celsius or less.

In step S130, the level of the piping temperature of the corresponding indoor unit to be operated is determined. The step S130 may be calculated together with the determination of the third entry condition of step S120.

In step S130, it is determined how much the piping temperature is, and control is performed accordingly.

In the present embodiment, the high pressure of the refrigerant is divided into three and the step S 130 is performed.

The first temperature level is " piping temperature ≥ 0 ° C.

The second temperature level is "-4 ° C <Piping temperature ≤ 0 ° C".

The second temperature level is "Piping temperature ≤ -4 ° C".

In step S140, the first subcooling expansion valve 127 controls the opening value according to the temperature level determined in step S130.

For example, at the first temperature level, the first supercooling expansion valve 127 is subjected to normal supercooling control. The normal supercooling control means the control of the first supercooling expansion valve 127 during the normal cooling operation.

At the second temperature level, the first subcooling expansion valve 127 controls the opening value by +10 pulses per 10 seconds.

At the third temperature level, the opening value of the first subcooling expansion valve 127 can be controlled with 20 pulses per 10 seconds.

In step S150, a release condition for terminating the control of the supercooling unit 120 under low load is determined. The release condition S150 is composed of a first release condition, a second release condition, a third release condition, and a fourth release condition.

The first release condition judges whether or not an out-of-cooling operation is input.

The second release condition determines whether the outside air temperature rises above the reference outside air temperature. In this embodiment, the outside air temperature rises to 0 ° C or higher.

The third release condition determines whether the compressor 10 exceeds the minimum operating frequency.

The fourth release condition is a case where the pipe temperature of the indoor heat exchanger exceeds 0 ° C.

When at least one of the first release condition, the second release condition, the third release condition, and the fourth release condition is satisfied, the control of the supercooling unit 100 for cooling continuous operation under low load is terminated.

After step S150, the compressor off condition is determined in step S160.

The compressor off condition is determined to be a case where the refrigerant supply amount of the indoor unit is large despite the control of the supercooling unit 100 in step S140 so that freezing of the indoor heat exchanger occurs.

If the compressor off condition is satisfied, the compressor is turned off in step S170.

If the compressor off condition is not satisfied, the process returns to step S120 to determine the entry condition again, and then repeats the following steps.

When the multi-type air conditioner is controlled as in the present embodiment, it is possible to continuously operate the compressor without turning off the compressor in the cooling low load state.

In the case of controlling the multi-type air conditioner as in the present embodiment, the operation stop due to the cooling low load can be minimized, thereby satisfying the cooling need of the consumer.

In the case of controlling the multi-type air conditioner as in the present embodiment, continuous operation can be performed at low load while suppressing freezing of the indoor heat exchanger even under cooling low load.

On the other hand, the receiver 110 can be additionally controlled for low load cooling continuous operation.

For example, when the step S120 is satisfied, the controller may control the first receiver valve 113 and the second receiver valve 115 to reduce the amount of refrigerant circulated.

If the step S150 is satisfied, the controller may control the first receiver valve 113 and the second receiver valve 115 to provide the refrigerant recovered to the system.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the meaning and scope of the claims and the equivalents thereof are included in the scope of the present invention Should be interpreted.

10: compressor 20: outdoor heat exchanger
22: first outdoor heat exchanger 24: second outdoor heat exchanger
30: accumulator 40: four-way valve
50: Oil separator 60: Outdoor blower fan
70: outdoor expansion valve 90: hot gas unit
100: supercooling unit 110: receiver

Claims (6)

A cooling step (S110);
(S120) during the cooling operation by determining the outside temperature, the compressor operating frequency, and the indoor pipe temperature and determining whether the inlet condition is satisfied;
Determining the piping temperature level when the entry condition (S120) is satisfied (S130);
The control unit controls the supercooling unit in accordance with the pipe temperature level determined in step S130 and controls the supercooling unit so that a part of the refrigerant flowing into the indoor unit through the liquid pipe in the outdoor heat exchanger during the control of the supercooling unit is passed through the supercooling bypass pipe, Adjusting the opening value of the supercooling expansion valve disposed in the supercooling bypass pipe (S140);
Determining a release condition after step S140 (S150);
If the release condition of S150 is satisfied, the process returns to step S110,
If the release condition of S150 is not satisfied, the control returns to step S120. The method according to claim 1,
Wherein the entry condition comprises a first entry condition, a second entry condition, and a third entry condition,
Wherein the first entry condition determines whether the outdoor temperature is lower than the reference outdoor temperature, and the second entry condition determines whether the operation frequency of the compressor is the minimum operation frequency, and the third entry condition determines whether the pipe temperature of the indoor unit And judging whether or not the temperature of the indoor unit is lower than the predetermined temperature. The method of claim 2,
Wherein the reference outside air temperature is 0 deg. The method according to claim 1,
In step S130, the high pressure level of the refrigerant is divided into a first temperature level, a second temperature level, and a third temperature level,
The first temperature level is " piping temperature ≥ 0 ° C, the second temperature level is -4 ° C <piping temperature ≤ 0 ° C, the second temperature level is piping temperature ≤ -4 ° C,
Controlling the supercooling unit to a normal cooling operation in the case of the first temperature level,
In the case of the second temperature level, the opening value of the supercooling expansion valve is controlled by +10 pulses per 10 seconds,
And the opening value is controlled by +20 pulses per 10 seconds for the supercooling expansion valve at the third temperature level. A cooling step (S110);
(S120) during the cooling operation by determining the outside temperature, the compressor operating frequency, and the indoor pipe temperature and determining whether the inlet condition is satisfied;
Determining the piping temperature level when the entry condition (S120) is satisfied (S130);
The control unit controls the supercooling unit in accordance with the pipe temperature level determined in step S130 and controls the supercooling unit so that a part of the refrigerant flowing into the indoor unit through the liquid pipe in the outdoor heat exchanger during the control of the supercooling unit is passed through the supercooling bypass pipe, Adjusting the opening value of the supercooling expansion valve disposed in the supercooling bypass pipe (S140);
Determining a release condition after step S140 (S150);
If it is determined that the release condition of S150 is satisfied, the process returns to step S110, and if the release condition of S150 is not satisfied, determining (S160) a compressor off condition;
And returning to step S120 if the step S160 is not satisfied, and when the step S160 is satisfied, turning off the compressor (S170). The method of claim 5,
Wherein the entry condition comprises a first entry condition, a second entry condition, and a third entry condition,
Wherein the first entry condition determines whether the outdoor temperature is lower than the reference outdoor temperature, and the second entry condition determines whether the operation frequency of the compressor is the minimum operation frequency, and the third entry condition determines whether the pipe temperature of the indoor unit And judging whether or not the temperature of the indoor unit is lower than the predetermined temperature.

Images