KR101588204B1 - Air conditioner and method for controlling air conditioner - Google Patents

Abstract

The present invention relates to a control method for an air conditioner and an air conditioner, and more particularly, to a control method for an air conditioner and an air conditioner, which comprises a refrigerant inflow pipe through which a refrigerant mixed with oil flows, a plurality of compressors connected to the refrigerant inflow pipe, A plurality of refrigerant discharge pipes connected to the plurality of compressors and through which the refrigerant compressed by the compressor is respectively discharged; a plurality of oil equalizing pipes each having a capillary tube for connecting the plurality of compressors to the refrigerant inlet pipe; And a controller for controlling the oil equalizing pipe based on the temperature value of the refrigerant in the refrigerant discharge pipe and the temperature value of the refrigerant passing through the capillary tube of the oil equalizing pipe, thereby providing an advantage that the oil can be supplied evenly between the plurality of compressors .

Description

[0001] The present invention relates to an air conditioner and an air conditioner,

The present invention relates to an air conditioner, and more particularly, to an air conditioner and an air conditioner control method for overcoming oil imbalance between a plurality of compressors.

Generally, an air conditioner is a device for cooling and / or heating an indoor space by performing heat exchange with indoor air while passing through a series of refrigerant cycles for compressing, condensing, expanding and evaporating refrigerant. Such an air conditioner is divided into an air conditioning air conditioner for supplying cool air to the room by operating the refrigerant cycle only in one direction and an air conditioner / air conditioner for supplying cold or warm air to the room by selectively operating the refrigerant cycle in both directions .

Such an air conditioner is divided into a conventional air conditioner in which one indoor unit is connected to one outdoor unit and a multi-type air conditioner in which a plurality of indoor units are connected to at least one outdoor unit.

Typically, a multi-type air conditioner is used for selectively air-conditioning a plurality of spaces partitioned in a building, and a plurality of compressors can be selectively operated as many as necessary according to the total air conditioning load.

In this case, when a plurality of compressors are operated together, oil flows into each of the compressors together with the refrigerant. The amount of oil in the compressor varies depending on the operation state of the compressors, A compressor may be generated. Particularly, in the case of a compressor in which oil is insufficient, problems such as burnout of the compressor, excessive noise or reduction of air conditioning efficiency due to deterioration of compressor performance may occur. Therefore, it is an important problem to supply oil evenly to a plurality of compressors.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an air conditioner and an air conditioner control method for preventing oil from being excessively supplied or under-supplied to each of a plurality of compressors.

Another object of the present invention is to provide an air conditioner and an air conditioner control method for supplying oil to each of a plurality of compressors equally.

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

The air conditioner of the present invention comprises a refrigerant inflow pipe through which an oil-mixed refrigerant flows, a plurality of compressors connected to the refrigerant inflow pipe for compressing and discharging the refrigerant, and a plurality of compressors connected to the compressors, A plurality of refrigerant discharge pipes through which the refrigerant compressed by the refrigerant discharge pipe is discharged and a plurality of oil equalizing pipes each having a capillary tube for connecting the plurality of compressors to the refrigerant inlet pipe; And a controller for controlling the oil equalizing pipe based on the temperature value of the refrigerant passing through the capillary of the pipe.

Here, the air conditioner is provided in each of the refrigerant discharge pipes, and includes a first temperature sensor for measuring the temperature of the refrigerant; And a second temperature sensor provided in each of the oil equalizing pipes corresponding to the first temperature sensor and measuring a temperature of the refrigerant passing through the capillary, And the measured value of the second temperature sensor.

The air conditioner may further include a plurality of equalizing valves respectively provided in the plurality of equalizing pipes. The control unit may control the air conditioner such that the difference between the measured value of the at least one first temperature sensor and the measured value of the second temperature sensor When the reference value is equal to or greater than the reference value, all the plurality of equalizing valves are opened.

It is preferable that the control unit determines that the difference between the measured value of the plurality of first temperature sensors and the measured value of the plurality of second temperature sensors measured again after all of the plurality of equalizing valves has been opened and the predetermined time has elapsed In the case of a cigarette of less than the reference value, all of the opened equalizing valves can be shut off.

The control unit may control the plurality of equalizing valves that are opened to be blocked after a set time has elapsed.

The air conditioner further includes: a plurality of oil separators for separating the oil contained in the refrigerant discharged by each of the compressors; And

And a plurality of oil recovery pipes connected to the plurality of oil separators and the plurality of compressors, respectively, for recovering oil separated by the oil separators to a compressor corresponding to the oil separator.

(A) measuring the discharge superheating degree of each of a plurality of compressors in operation; and (c) measuring a discharge superheat degree of at least one of the plurality of compressors when a discharge superheat degree of at least one of the compressors is equal to or greater than a reference value, And (b) in which oil above the oil level is distributed to the refrigerant inflow pipe through the oil equalizing pipe corresponding to the compressor.

The step (a) includes: (a-1) measuring a temperature of a refrigerant discharged from each of the plurality of compressors; And (a-2) measuring the temperature of the refrigerant flowing from the plurality of compressors to the oil equalizing pipe side and passing through the capillary.

The step (b) may include opening all of the equalizing valves provided on the plurality of equalizing pipes connected to the respective compressors when the discharge and the degree of heat of the at least one compressor are equal to or more than a predetermined value, have.

The step (b) further includes the steps of: (b-1) measuring the temperature of the refrigerant discharged from each of the plurality of compressors again after the plurality of equalizing valves are opened; and And (b-2) measuring the temperature of the refrigerant flowing through the capillary. At this time, if the discharge superheating degree calculated on the basis of the temperature value measured in the step (b-1) and the temperature value measured in the step (b-2) And closing all of the plurality of equalizing valves. Further, the method may further include the step (c) of blocking all the opened equalizing valves when the set time has elapsed.

According to the air conditioner and the air conditioner control method of the present invention, one or more of the following effects can be obtained.

First, there is an effect that the oil can be equalized by the compressor which lacks the oil from the excessive compressor, so that the compressor lacking the oil is not present.

Second, there is an effect of preventing the compressor parts from being burned out due to oil shortage.

Third, it is possible to prevent the oil from being unbalanced due to the difference in the number of rotations of the compressors.

Fourth, the oil separated from the oil recovery unit can be returned to the compressor without mixing with the refrigerant, thereby improving the compression capacity and the COP of the system.

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.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with 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.

1 is a configuration diagram of an air conditioner according to an embodiment of the present invention. 2 is an enlarged view for explaining the configuration of the outdoor unit 100 shown in FIG. 1 in more detail. 1 and 2, an air conditioner according to an embodiment of the present invention includes a plurality of outdoor units 100 and a plurality of indoor units 200. At least one of the outdoor unit 100 and the indoor unit 200 may be included, and the scope of the present invention is not limited by the number. A high-low-pressure common pipe 117 for balancing the high-pressure or low-pressure refrigerant between the plurality of outdoor units 100 may be installed.

The outdoor unit 100 includes a plurality of compressors 120a, 120b and 120c, an outdoor heat exchanger 176, an outdoor expansion valve 171 and a subcooler 180 connected to each other by a refrigerant pipe 110 . On the refrigerant pipe 110, pressure sensors 175 and 177 may be provided to measure the pressure of the refrigerant flowing. In addition, a solenoid valve 174 may be provided on the refrigerant pipe 110 to adjust the amount of the refrigerant flowing.

The compressors 120a, 120b, and 120c compress the low temperature low pressure refrigerant into the high temperature high pressure refrigerant. Various constructions can be applied to the compressors 120a, 120b, and 120c, and inverter type compressors or constant speed compressors can be employed. Refrigerant is supplied to each of the compressors 120a, 120b, and 120c through a refrigerant inflow pipe 111. More specifically, each of the compressors 120a, 120b, and 120c receives refrigerant from corresponding refrigerant inflow pipes 111a, 111b, and 111c. In order to prevent liquid refrigerant from flowing into the compressors 120a, 120b, and 120c, the refrigerant inflow pipe 111 may be provided with an accumulator 162.

Each of the compressors 120a, 120b, and 120c discharges the compressed refrigerant to the corresponding refrigerant discharge pipe 113a, 113b, and 113c. On the refrigerant discharge pipes 113a, 113b and 113c, pressure switches 132a, 132b and 132c for regulating the pressure of the refrigerant to be discharged can be provided.

The oil contained in the refrigerant discharged to each of the refrigerant discharge pipes 113a, 113b and 113c is separated by the oil separators 140a, 140b and 140c, and the oil separated by the oil return pipes 113a, 113b and 113c, (120a, 120b, 120c), respectively. That is, the refrigerant compressed by the compressors 120a, 120b, and 120c includes a predetermined amount of oil to smoothly operate the compressors 120a, 120b, and 120c. The oil separators 140a, 140b, The oil contained in the oil is returned to each of the compressors 120a, 120b and 120c through the oil recovery pipes 113a, 113b and 113c to maintain a certain level of oil in the compressors 120a, 120b and 120c . At this time, the oil return pipes 113a, 113b and 113c directly connect the oil separators 140a, 140b and 140c to the compressors 120a, 120b and 120c and are compressed by the compressors 120a, 120b and 120c, Only the oil separated in the refrigerant is returned to each of the compressors 120a, 120b and 120c.

The four-way valve 172 is a flow-switching valve for switching heating and cooling. The four-way valve 172 guides the refrigerant compressed by the compressors 120a, 120b, and 120c to the outdoor heat exchanger 176 during the cooling operation, .

The outdoor heat exchanger 176 is generally disposed in the outdoor space, and the refrigerant that has passed through the outdoor heat exchanger 176 performs heat exchange with the outdoor air. The outdoor heat exchanger 176 acts as a condenser during cooling operation and as an evaporator during heating operation. The outdoor expansion valve (171) expands the refrigerant flowing in the heating operation. Between the outdoor air and the outdoor heat exchanger 178, a blower 178 for dissipating the heat generated during heat exchange to the outside may be provided.

The first bypass pipe 179 is provided so that the refrigerant passing through the outdoor heat exchanger 176 bypasses the outdoor expansion valve 171 and the check valve 173 for interrupting the first bypass pipe 179 is provided. . The check valve 173 is opened during the cooling operation so that the refrigerant passing through the heat exchanger 176 flows into the first bypass pipe 179.

The subcooling device 180 includes a subcooling heat exchanger 182, a second bypass pipe 181, and a subcooling expansion valve 184. During the cooling operation, the second bypass pipe 181 functions to bypass the refrigerant discharged from the supercool heat exchanger 184 and to introduce the refrigerant to the supercooled expansion valve 184.

The subcooling expansion valve 184 is disposed on the second bypass pipe 181 to expand the liquid refrigerant flowing into the second bypass pipe 181 to lower the pressure and the temperature and then to supply the supercooling heat exchanger 182 Lt; / RTI > Various types of subcooling expansion valve 184 may be used, and a linear expansion valve may be used from the viewpoint of ease of use and control.

During the cooling operation, the refrigerant condensed while passing through the outdoor heat exchanger 176 is heat-exchanged in the subcooling heat exchanger 182 with the low-temperature refrigerant introduced through the second bypass pipe 181, To the plurality of indoor units (200). The refrigerant passing through the second bypass pipe 181 flows through the supercool heat exchanger 182 and flows into the accumulator 162.

In one embodiment of the present invention, the plurality of indoor units 200 includes an indoor expansion valve 210, an indoor heat exchanger 220, and an indoor air blower 230 for blowing heat-exchanged air into the room. The air conditioner may include one or a plurality of indoor units 200, and four indoor units 200 are provided in this embodiment.

The indoor heat exchanger 220 is generally disposed in the indoor space, and the refrigerant passing through the indoor heat exchanger 220 is heat-exchanged with the indoor air. The indoor heat exchanger 220 functions as an evaporator during cooling operation and as a condenser during heating operation.

The indoor expansion valve (210) is a device for expanding the refrigerant flowing in the cooling operation. Various types of indoor expansion valves 210 may be used, and a linear expansion valve may be used from the viewpoint of ease of use and control. The opening degree of the indoor expansion valve 210 can be adjusted according to the air conditioning load of the indoor unit 200 and the air conditioning capacity of the indoor unit 200.

The flow of the refrigerant during the cooling operation of the above-described air conditioner is as follows.

The high-temperature, high-pressure gaseous refrigerant discharged from the compressors 120a, 120b, 120c flows into the outdoor heat exchanger 176 through the four-way valve 172. In the outdoor heat exchanger (176), the refrigerant is heat-exchanged with outdoor air and condensed. The refrigerant passing through the outdoor heat exchanger 176 passes through the outdoor expansion valve 171 and then is supercooled while passing through the supercooler 180 and then flows into the indoor unit 200 through the liquid pipe 115.

At this time, the refrigerant in the second bypass pipe 181 of the subcooler 180 flows to the accumulator 162. On the other hand, the refrigerant flowing into each indoor unit 200 is expanded in the indoor expansion valve 210 opened by a predetermined opening degree, and is heat-exchanged with indoor air in the indoor heat exchanger 220 to be evaporated. The evaporated refrigerant flows through the engine 116 to the accumulator 162 via the four-way valve 172. Therefore, the refrigerant collected through the second bypass pipe 181 of the supercooler 180 and the refrigerant introduced from the indoor unit 200 are collected together in the accumulator 162, and the collected refrigerant flows again through the refrigerant inflow pipe 111 To the respective compressors 120a, 120b, and 120c, thereby continuously performing a cooling cycle.

The flow of the refrigerant during the heating operation of the above-described air conditioner is as follows.

Temperature and high-pressure gaseous refrigerant discharged from the compressors 120a, 120b and 120c flows into the indoor unit 200 through the four-way valve 172 and the engine 116. [ The refrigerant flowing into the indoor unit 200 flows through the indoor heat exchanger 220 and is heat-exchanged with the indoor air to be condensed. The refrigerant is introduced into the outdoor unit 100 through the liquid pipe 115 and then flows through the outdoor expansion valve 171, Exchanges heat with the outdoor air while passing through the outdoor heat exchanger 176, and evaporates. The evaporated refrigerant flows into the compressors 120a, 120b, and 120c through the four-way valve 172, the accumulator 162, and the refrigerant inflow pipe 111, thereby continuously performing the heating cycle.

The flow of the oil contained in the refrigerant in the above-mentioned air conditioner is as follows.

The refrigerant flowing into the compressors 120a, 120b, and 120c through the refrigerant inlet pipes 111a, 111b, and 111c includes oil. The oil introduced into each of the compressors 120a, 120b and 120c together with the refrigerant is discharged to the refrigerant discharge pipes 112a, 112b and 112c together with the refrigerant and flows into the oil separators 140a, 140b and 140c, respectively. The oil separators 140a, 140b and 140c separate the oil from the refrigerant and recover the oil to the compressors 120a, 120b and 120c through the oil return pipes 113a, 113b and 113c. At this time, since the oil separators 140a, 140b and 140c separate only the oil from the refrigerant compressed and discharged by the compressors 120a, 120b and 120c and return them to the respective compressors 120a, 120b and 120c, The refrigerant is prevented from being reintroduced into the compressors 120a, 120b, and 120c, thereby improving the compression efficiency and the COP of the system.

When oil equal to or higher than the reference oil level is collected in each of the compressors 120a, 120b, and 120c, oil exceeding the reference oil level is distributed to the refrigerant inflow pipe 111 through the oil equalizing oil pipes 114a, 114b, and 114c. The oil distributed to the refrigerant inlet pipe 111 is supplied to the respective compressors 120a, 120b and 120c together with the refrigerant. The process of distributing the oil between the respective compressors 120a, 120b and 120c will be described later in more detail.

FIG. 3 is a partial view of FIG. 1 and FIG. 2, illustrating an equalization process among a plurality of compressors 120a, 120b, and 120c. 4 is a block diagram showing the configuration of the main part of the air conditioner according to the embodiment of the present invention.

3 to 4, in the air conditioner according to the embodiment of the present invention, when oil above a reference oil level is collected in any one of the plurality of compressors 120a, 120b, and 120c, The refrigerant flowing into the refrigerant inflow pipe 111 through the oil equalizing piping 114a, 114b, The reference oil level may be defined as the oil level of the oil in the compressor, which is set based on the amount of oil required for the compressors 120a, 120b, and 120c to operate smoothly.

The control unit 150 controls the temperature of the refrigerant in the refrigerant discharge pipes 112a, 112b and 112c and the temperature values of the refrigerant passing through the capillaries 137a, 137b and 137c of the oil equalizing pipes 114a, 114b and 114c , The oil equalizing pipes (114a, 114b, 114c) are interrupted.

Equal oil valves 135a, 135b and 135c are provided in the oil equalizing oil pipes 114a, 114b and 114c, respectively. The control unit 150 determines whether or not oil exceeding the reference oil level is collected in each of the compressors 120a, 120b, and 120c, and controls so that the oil equalizing valve corresponding to the compressor in which the oil over the reference oil level is collected is opened. When the equalizing valve is opened by the control unit 150, oil above the reference oil level flows into the refrigerant inflow pipe 111.

The control unit 150 calculates the discharge superheat degree of each of the compressors 120a, 120b, and 120c, and determines whether or not oil over the reference oil level is collected in the compressors 120a, 120b, and 120c. The discharge overheating degree is calculated based on the temperature of the refrigerant discharged by the compressors 120a, 120b, and 120c and the temperature difference of the refrigerant flowing into the equalizing pipe 114a, 114b, and 114c.

The air conditioner includes first temperature sensors 131a, 131b and 131c provided on the refrigerant discharge pipes 112a, 112b and 112c for measuring the temperature of the refrigerant discharged from the compressors 120a, 120b and 120c, And second temperature sensors 133a, 133b, and 133c provided on the pipes 114a, 114b, and 114c.

If the temperature value measured by the first temperature sensors 131a, 131b and 131c is Td and the temperature value measured by the second temperature sensors 133a, 133b and 133c is Tpipe, the above- Can be defined as follows.

Discharge superheat = Td-Tpipe;

The discharge and the degree of heat are calculated using the Tpipe value that varies depending on the influence of the oil contained in the refrigerant flowing into the oil equalizing pipes 114a, 114b, and 114c, and based on this, the compressors 120a, 120b, Can be judged.

More specifically, the refrigerant flowing into the oil equalizing piping 114a, 114b, and 114c is adiabatically expanded while passing through the capillaries 137a, 137b, and 137c, and the temperature thereof drops. Therefore, it is general that the temperature values measured by the second temperature sensors 133a, 133b, 133c are measured to be smaller than the temperature values measured by the first temperature sensors 131a, 131b, 131c. As the amount of the oil contained in the refrigerant flowing into the oil equalizing pipes 114a, 114b, and 114c is smaller, the amount of the refrigerant to be thermally expanded becomes larger as the refrigerant passes through the capillaries 137a, 137b, and 137c, It will lose. That is, the smaller the amount of oil contained in the refrigerant flowing into the equalizing oil piping 114a, 114b, 114c, the lower the Tpipe value and the higher the discharge superheat degree. On the contrary, if the refrigerant flowing into the oil equalizing pipes 114a, 114b, and 114c contains a large amount of oil, the Tpipe value is measured to be relatively high and the discharge superheat degree is low (see FIG. 6).

5 is a graph for explaining the relationship between the amount of oil flowing into the compressor and the discharge superheating degree. Referring to FIG. 5, the discharge superheat degree (Td-Tpipe) is a graph in which the value of the discharge superheat degree (Td-Tpipe) decreases as the temperature of the outside air increases. The graph shows a state in which oil below the reference oil level is collected in the compressors 120a, 120b, and 120c on the basis of the discharge superheat curve (a) measured in a state where oil is collected to the reference oil level The curve (b) and the curve (c) in which the oil over the reference oil level is collected in the compressors (120a, 120b, 120c) are shown in comparison.

b curve shows that the discharge superheat value is higher than the a curve, and the c curve shows that the discharge superheat value is lower than the a curve. When the amount of oil collected in the compressors 120a, 120b, and 120c is equal to or lower than the reference oil level, only the refrigerant flows into the oil equalizing pipes 114a, 114b, and 114c. The refrigerant flowing into the oil equalizing piping 114a, 114b, and 114c is adiabatically expanded while passing through the capillaries 137a, 137b, and 137c. Therefore, at this time, the temperature Tpipe measured by the second temperature sensors 133a, 133b, and 133c is measured to be a low value, and the discharge superheat degree Td-Tpipe becomes high. Conversely, if the amount of oil collected in the compressors 120a, 120b and 120c is equal to or greater than the reference oil level, oil exceeding the reference oil level flows into the oil equalizing pipes 114a, 114b, and 114c and the second temperature sensors 133a, 133b, and 133c ) Is measured at a relatively high value, and the discharge superheating degree (Td-Tpipe) is relatively low.

6 is a flowchart illustrating a method of controlling an air conditioner according to an embodiment of the present invention. Referring to FIG. 6, a normal operation step in which the air conditioner is operated to cool or heat indoor air is performed. (S10) At step S10, at least one compressor is operated. If two or more compressors are operated in step S10 (S20), the operation of the compressor is continued for a predetermined time (S30). The predetermined time may be set to two hours.

Hereinafter, it is assumed that the three compressors 120a, 120b, and 120c are all operating in step S10. Also, the predetermined time is set to 2 hours, but the present invention is not limited thereto, and may be variously set according to the air conditioning load or the compressor efficiency.

After the compressors 120a, 120b and 120c are operated for two hours, the discharge superheat degree of each of the compressors 120a, 120b and 120c is measured, and the measured discharge superheat is compared with the reference value. (S40) The discharge superheat degree is a numerical value for judging whether or not oil above the reference oil level is collected in each of the compressors 120a, 120b, and 120c as described above. In the present embodiment, the reference value is set to 10 degrees, but the present invention is not limited thereto, and the compression efficiency and the like varying depending on the limit capacity of the oil accommodated by the compressors 120a, 120b and 120c and the amount of oil contained in the refrigerant Can be set in various ways. For convenience of explanation, it is assumed that the discharge superheat degree of the compressor 120a is measured at 10 degrees or more and the discharge and the circulation of the compressors 120b and 120c are measured at 10 degrees or less in step S40.

When the discharge superheat degree of at least one compressor 120a is 10 degrees or more, the controller 150 controls all the equalizing valves 135a, 135b, and 135c to be opened for a predetermined time. In the present embodiment, the predetermined time is set to 90 seconds, but the present invention is not limited thereto. Various times may be set. (S50)

When the oil equalizing valves 135a, 135b and 135c are opened, oil above the reference oil level collected in the compressor 120a flows into the refrigerant inflow pipe 111 through the oil equalizing pipe 114a, and the respective compressors 120a, 120b, 120c and flows together with the refrigerant. In this process, the oil over the reference oil level is distributed from the compressor 120a to the compressor 120b and the compressor 120b, and this process is repeated for the time when the oil equalizing valves 135a, 135b, and 135c are open. In this process, when oil is excessively supplied to the compressor 120b or the compressor 120c, the excessively supplied oil is redistributed again through the oil equalizing pipes 114b and 114c to the refrigerant inflow pipe 111, The oil is finally supplied to the respective compressors 120a, 120b, and 120c while being repeatedly supplied.

When the discharge superheat degree of all the compressors 120a, 120b and 120c in operation becomes equal to or lower than the reference value (S60) by the oil redistribution process as described above, that is, the first temperature sensors 131a, 135b and 135c If the difference between the measured value and the second temperature sensor 133a, 133b, 133c is less than 10 degrees, the controller 150 cuts off all the opened equalizing valves (S61) and ends the equalizing process (S70)

On the other hand, if at least one of the plurality of compressors 120a, 120b, and 120c has a discharge superheat degree equal to or higher than the reference value at step S60, oil is supplied to at least one of the plurality of compressors 120a, 120b, and 120c Or the amount of oil supplied through the refrigerant inlet pipe 111 is insufficient to operate all of the plurality of compressors 120a, 120b, and 120c. Therefore, in this case, the equalizing valve is further kept open for a predetermined time (S62), and after the set time (here, four minutes) elapses from the time when the equalizing valves 135a, 135b and 135c are opened ), All the equalizing valves 135a, 135b and 135b are shut off. This completes the process of balancing the oil between the plurality of compressors 120a, 120b and 120c (S70)

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.

1 is a configuration diagram of an air conditioner according to an embodiment of the present invention.

Fig. 2 is an enlarged view for explaining the construction of the outdoor unit shown in Fig. 1 in more detail.

FIG. 3 is a partial view of FIG. 1 and FIG. 2 to explain the equalization process among a plurality of compressors.

4 is a block diagram showing the configuration of the main part of the air conditioner according to the embodiment of the present invention.

5 is a graph for explaining the relationship between the amount of oil flowing into the compressor and the discharge superheating degree.

6 is a flowchart illustrating a method of controlling an air conditioner according to an embodiment of the present invention.

Description of the Related Art

100: outdoor unit 110: refrigerant piping

111: Refrigerant inlet pipe 112a, 112b, 112c: Refrigerant outlet pipe

113a, 113b, and 113c: Oil recovery pipes 114a, 114b, and 114c:

115: liquid pipe 116: engine

117: high and low pressure common pipes 120a, 120b and 120c:

131a, 131b and 131c: first temperature sensors 133a, 133b and 133c:

135a, 135b, 135c: equalizing valves 137a, 137b, 137c:

140a, 140b, 140c: Oil separator 150:

Claims (13)

A refrigerant inflow pipe through which the refrigerant mixed with the oil flows; A plurality of compressors connected to the refrigerant inflow pipe, respectively, for compressing and discharging the refrigerant; A plurality of refrigerant discharge pipings connected to the plurality of compressors and through which the refrigerant compressed by the compressor is discharged; A plurality of oil equalizing pipes having a capillary tube and connecting the plurality of compressors to the refrigerant inflow pipe; A plurality of oil equalizing valves respectively provided in the plurality of oil equalizing pipes; A first temperature sensor provided in each of the refrigerant discharge pipes for measuring the temperature of the refrigerant; A second temperature sensor provided in each of the oil equalizing pipes corresponding to the first temperature sensor, the second temperature sensor measuring the temperature of the refrigerant passing through the capillary; And Both of the difference values between the measured value of the first temperature sensor and the measured value of the second temperature sensor obtained for each of the compressors are set in advance in a state in which the plurality of compressors are driven and all of the plurality of equalizing valves are opened And a control unit for shutting off all of the plurality of equalizing valves when the difference values are equal to or more than the reference value and all of the difference values are equal to or lower than the reference value and otherwise maintaining the plurality of equalizing valves in the open state for a predetermined time Air conditioner. The method according to claim 1, The difference between the measured value of the first temperature sensor and the measured value of the second temperature sensor, Wherein all of the plurality of equalizing valves are opened after a predetermined time has passed. The method according to claim 1, Wherein, And closes all of the plurality of equalizing valves after the set time has elapsed. The method according to claim 1, A plurality of oil separators for separating the oil contained in the refrigerant discharged by each of the compressors; And Further comprising a plurality of oil return pipes connecting the plurality of oil separators and the plurality of compressors, respectively, to recover the oil separated by the oil separators to the compressor corresponding to the oil separator. A plurality of compressors connected to the refrigerant inlet pipe for compressing and discharging the refrigerant, respectively, and a refrigerant connected to the plurality of compressors and compressed by the compressor, A plurality of equalizing valves each having a plurality of refrigerant discharge pipes to be discharged and a capillary tube for connecting the plurality of compressors and the refrigerant inlet pipe, and a plurality of equalizing valves respectively provided in the plurality of equalizing pipes; A first temperature sensor provided in the refrigerant discharge pipe for measuring the temperature of the refrigerant; a second temperature sensor provided in each of the oil equalizing pipes, corresponding to the first temperature sensor, for measuring the temperature of the refrigerant passing through the capillary, A control method for an air conditioner including a temperature sensor, Opening all the plurality of equalizing valves corresponding to the driven compressors while the plurality of compressors are being driven; Both of the difference values between the measured value of the first temperature sensor and the measured value of the second temperature sensor, which are obtained for each of the driven compressors, are equal to or more than a preset reference value, And closes all of the opened equalizing valves when all of the difference values are equal to or less than the reference value, and otherwise keeps the plurality of equalizing valves in the open state for a predetermined time. 6. The method of claim 5, And closing all of the plurality of equalizing valves after the set time has elapsed. 6. The method of claim 5, Wherein the difference between the measured value of the first temperature sensor and the measured value of the second temperature sensor is obtained at a time when a predetermined time has elapsed after the plurality of equalizing valves are opened. delete delete delete delete delete delete

Images