KR101977984B1 - Air conditioner and method for controlling the same - Google Patents

Abstract

The present invention relates to an air conditioner and a control method thereof. An air conditioner according to one aspect includes: a plurality of compressors; A plurality of oil sensors provided in each of the plurality of compressors to sense an oil level; A plurality of bypass piping through which the oil or refrigerant discharged from each of the plurality of compressors flows; A valve for controlling the flow of oil or refrigerant to each bypass pipe; And a common suction pipe provided at a suction side of the plurality of compressors and through which the refrigerant or oil flowing in each bypass pipe flows, and the operation of the valve based on the oil level sensed by the plurality of oil sensors Is controlled.

Description

Air conditioner and method of controlling same

The present invention relates to an air conditioner and a control method thereof.

Generally, an air conditioner is a device that adjusts the temperature and humidity of air while performing a series of cycles of compression-condensation-expansion-evaporation.

In recent years, a plurality of indoor units are connected to one or a plurality of outdoor units. The outdoor unit may include a plurality of compressors depending on the capacity of the plurality of indoor units.

An oil separator for separating oil is provided on the discharge side of each of the compressors. The oil separated from each of the oil separators is transferred to the suction side of each of the compressors through an oil return pipe.

In the conventional air conditioner, the refrigerant and the oil of the compressor are bypassed at a constant cycle to flow to the suction side of the compressor for equalizing the refrigerant between the compressors. However, according to the conventional air conditioner, since the refrigerant or oil is bypassed at regular intervals, there is a problem that the oil is bypassed even when the refrigerant flows in the compressor, and thus there is an unnecessary process.
The following is a list of prior literature information.
1. Publication No. (Published Date): Published Patent Application No. 10-2011-0110662 (Oct.
Title: An air conditioner having a plurality of compressors and a driving method thereof

SUMMARY OF THE INVENTION An object of the present invention is to provide an air conditioner and a control method thereof for sensing an oil level of each of a plurality of compressors to cause an equalizing process to be performed when oil is insufficient in some compressors.

An air conditioner according to one aspect includes: a plurality of compressors; A plurality of oil sensors provided in each of the plurality of compressors to sense an oil level; A plurality of bypass piping through which the oil or refrigerant discharged from each of the plurality of compressors flows; A valve for controlling the flow of oil or refrigerant to each bypass pipe; And a common suction pipe provided at a suction side of the plurality of compressors and through which the refrigerant or oil flowing in each bypass pipe flows, and the operation of the valve based on the oil level sensed by the plurality of oil sensors Is controlled.

According to another aspect of the present invention, there is provided a control method for an air conditioner comprising a plurality of compressors, a bypass pipe connected to each of the plurality of compressors, a refrigerant or oil connected to a suction side of the plurality of compressors, And a valve for controlling a flow of a refrigerant or oil in the bypass pipe, the control method comprising the steps of: detecting an oil level in an oil sensor provided in each of the plurality of compressors; ; Comparing the oil level sensed by each oil sensor with a reference level; And opening the valve if the oil level sensed by some of the plurality of oil sensors is less than a reference level as a result of the comparison.

According to the present invention, when excess oil is stored in a specific compressor, the oil is discharged to the outside of the compressor through a bypass pipe connected to the compressor, and then is distributed to the compressors. . Damage to the compressor can be prevented when the phenomenon of oil shortage in the compressor is prevented.

Further, since the excess oil of the specific compressor is uniformly distributed to the respective compressors, there is an advantage that the oil level unbalance between the compressors is eliminated.

In addition, since the oil level can be performed when the sensing value of some of the oil sensors is smaller than the reference value, it is prevented that the oil level is unnecessarily performed, thereby preventing the efficiency and capability of the air conditioner from being lowered .

1 is a partial structural view of a refrigerant cycle of an air conditioner according to a first embodiment;
2 is a flow chart for explaining a control method of the air conditioner according to the first embodiment;
3 is a partial structural view of the refrigerant cycle of the air conditioner according to the second embodiment;

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the difference that the embodiments of the present invention are not conclusive.

In describing the components of the embodiment of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; may be " connected, " " coupled, " or " connected. &Quot;

FIG. 1 is a partial configuration diagram of a refrigerant cycle of the air conditioner according to the first embodiment.

Referring to FIG. 1, the air conditioner according to the first embodiment may include a plurality of compressors 11 and 12 arranged in parallel. In the first embodiment, it is described that there are two compressors, but it is to be noted that there is no limitation on the number of the compressors.

In this embodiment, the compressors 11 and 12 may have different capacities. Further, some compressors may be inverter compressors with variable speeds, and other compressors may be constant speed compressors. Of course, the capacities of the compressors 11 and 12 may be the same.

A suction pipe unit is connected to each of the compressors 11 and 12 so that refrigerant discharged from an evaporator (not shown) is sucked. The suction pipe unit includes a common suction pipe 30 through which refrigerant discharged from the evaporator flows and a plurality of individual suction pipes 31 and 32 branched from the common suction pipe 30 and connected to the compressors 11 and 12 ).

Therefore, the refrigerant flowing into the common suction pipe 30 is distributed to the individual suction pipes 31 and 32, and then is transferred to the compressors 11 and 12. The common suction pipe 30 may be connected to the accumulator 10. The accumulator 10 separates the gaseous refrigerant and the liquid refrigerant from the refrigerant that has passed through the evaporator.

Then, only the separated gaseous refrigerant is transferred to the common suction pipe 30, and the separated liquid refrigerant is stored in the accumulator 10.

The discharge piping unit through which the refrigerant discharged from the respective compressors (11, 12) flows is connected to the compressors (11, 12). The discharge piping unit includes a plurality of individual discharge pipes 33 and 34 connected to the discharge side of the compressors 11 and 12 and refrigerant flowing along the discharge pipes 33 and 34 And a common discharge pipe (35).

Accordingly, the refrigerant discharged from the respective compressors 11 and 12 flows along the individual discharge pipes 33 and 34, and is then transferred to the condenser not shown after being combined in the common discharge pipe 35.

The individual discharge pipes 33 and 34 are provided with oil separators 21 and 22 for separating refrigerant and oil discharged from the respective compressors 11 and 12.

Oil recovery pipes 23 and 24 are connected to the oil separators 21 and 22 to recover the oil separated from the oil separators 21 and 22 to the respective compressors 11 and 12. The oil return pipes 23 and 24 may be connected to the respective compressors 11 and 12 or may be connected to the individual suction pipes 31 and 32.

Accordingly, refrigerant and oil discharged from the compressors 11 and 12 are separated by the oil separators 21 and 22, and the separated oil is supplied to the respective compressors 11 and 22 corresponding to the oil separators 21 and 22, 12).

A bypass unit is connected to each of the compressors 11 and 12 to discharge excess oil to the outside of the compressors 11 and 12 when excess oil is stored in the compressors 11 and 12.

The bypass unit includes a plurality of bypass pipes 43 and 43 connected to the compressors 11 and 12 and an oil or coolant flowing along the bypass pipes 42 and 43 And a common pipe (41). The common pipe (41) may be connected to the common suction pipe (30).

Each of the bypass pipes 42 and 43 may be connected to the respective compressors 11 and 12 at a position higher or lower than the minimum oil level required for the compressors 11 and 12.

Depending on the oil level in each of the compressors 11 and 12, only the refrigerant may be discharged to the bypass piping 42 or 43, only the oil may be discharged, or the refrigerant and the oil may be discharged together. In the present specification, the refrigerant and the oil will collectively be referred to as a fluid.

Since the oil level required by the compressors 11 and 12 varies depending on the capacities of the compressors 11 and 12, the connecting positions of the bypass pipes 51 and 52 are also different from the compressors 11 and 12 ). ≪ / RTI >

Each of the bypass pipes 42 and 43 is provided with depressurizing portions 44 and 45 for depressurizing the fluid discharged from the compressors 11 and 12, Check valves 46 and 47 may be provided to prevent backflow into the compressors 11 and 12, respectively. The check valves (46, 47) are provided on the outlet sides of the pressure reducing portions (44, 45). That is, the check valves 46 and 47 are located downstream of the depressurizing portions 44 and 45. As the pressure-sensitive portions 44 and 45, a capillary may be used as an example.

The common pipe 41 may be provided with an electronic expansion valve 48 for regulating the flow rate. When the electronic expansion valve 48 is opened, the fluid can be discharged from the respective compressors 11 and 12 to the respective bypass pipes 42 and 43.

The reason for using the electronic expansion valve 48 in this embodiment is as follows. When the air conditioner is operated at a low temperature (for example, below 0 degrees), the viscosity of the fluid flowing through the bypass pipe 42, 43 is increased. In the present embodiment, the electronic expansion valve 48 is installed in the common pipe 41 because the electronic expansion valve 48 is also suitable for a high fluidity viscosity.

Illustratively, a high pressure compressor may be used for each of the compressors 11 and 12. The high-pressure compressor has a high-pressure space in which oil is stored. When the high pressure type compressor is used, the pressure inside the compressors 11 and 12 is higher than the pressure of the bypass piping 11 and 12. Therefore, when the electronic expansion valve 48 is opened, the fluid in the compressors 11 and 12 can be discharged to the respective bypass pipes 42 and 43.

The decompression units 44 and 45 expand the fluid flowing along the bypass pipes 42 and 43 to lower the temperature and the pressure.

When the refrigerant is discharged from the compressors 11 and 12 to the bypass piping 42 and 43, the discharged refrigerant is moved to the suction side of the compressors 11 and 12. Here, a low-pressure refrigerant must flow into the suction side of the compressors (11, 12). In this embodiment, since the refrigerant flowing into the bypass piping 42 and 43 is in a high pressure state, the refrigerant flowing through the bypass piping 42 and 43 is decompressed by the decompression units 44 and 45 do.

Each of the compressors 11 and 12 is provided with oil sensors 13 and 14 for sensing an oil level. It should be noted that the oil sensors 13 and 14 may be sensors using capacitors as an example, but the types of the oil sensors 13 and 14 are not limited.

The oil level sensed by the oil sensors 13 and 14 may be equal to or higher than the oil level at which the bypass piping 42 and 43 are connected to the compressors 11 and 12.

The oil level information sensed by the oil sensors 13 and 14 is transmitted to a control unit (not shown), and the control unit controls the electronic expansion valve 48 based on the oil level information.

2 is a flowchart for explaining a control method of the air conditioner according to the first embodiment.

Referring to FIG. 2, when a user's operation command is input, the air conditioner operates in a selected mode (S1). When the air conditioner operates, the refrigerant is compressed in the respective compressors (11, 12), and the compressed refrigerant is discharged to the individual discharge pipes (33, 34).

During operation of the air conditioner, the oil level in each of the compressors (11, 12) is sensed by the oil sensors (13, 14).

Then, the controller determines whether the sensed value of at least one of the plurality of oil sensors 13 and 14 is smaller than a reference value (S2). That is, it is determined whether or not the oil level detected by the oil sensor is smaller than the reference level.

If the detection value of some of the oil sensors 13 and 14 is smaller than the reference value, the control unit controls the electronic expansion valve 48 to be opened.

For example, when the sensed values of the oil sensors 13 and 14 are equal to or greater than the reference value, it is determined that oil does not run short in the respective compressors, so that the electronic expansion valve 48 remains closed.

If the detection value of some of the oil sensors 13 and 14 is smaller than the reference value, the oil level of some of the compressors is insufficient and the oil level of the remaining compressors is insufficient. Or the electronic expansion valve 48 is opened such that the oil level is equal to or higher than the reference level.

Illustratively, when oil of a level higher than the reference level is stored in the first compressor 11 and oil of a level lower than the reference level is stored in the second compressor 12, the electronic expansion valve 48 The oil is discharged to the first bypass pipe 42 and the refrigerant is discharged to the second bypass pipe 43. Then, the discharged oil and refrigerant are introduced into the common suction pipe 30 after they are combined in the common pipe 41. Then, refrigerant and oil are sucked into the respective compressors (11, 12) after the refrigerant and oil are distributed to the individual suction pipes (31, 32) in the common suction pipe (30).

The oil level of the second compressor 12 is increased as the oil discharged from the first compressor 11 is divided into the first compressor 11 and the second compressor 12. [

In a state in which the electronic expansion valve 48 is open, the control unit determines whether each sensing value of the plurality of oil sensors is equal to or greater than a reference value (S4).

If the detection value of each of the oil sensors is equal to or greater than the reference value, the control unit controls the electronic expansion valve (48) to be closed.

In this specification, the mode in which the electronic expansion valve is opened and the oil discharged from some compressors is distributed to each compressor may be referred to as an equalizing mode.

According to the present embodiment, when excess oil is stored in a specific compressor, the oil is discharged to the outside of the compressor through the bypass pipe connected to the compressor, and then is distributed to the compressors. . Damage to the compressor can be prevented when the phenomenon of oil shortage in the compressor is prevented.

Further, since the excess oil of the specific compressor is uniformly distributed to the respective compressors, there is an advantage that the oil level unbalance between the compressors is eliminated.

Further, since the electronic expansion valve is installed in the common pipe, the operation of the electronic expansion valve can be smoothly performed even when the air conditioner operates at a low temperature.

In addition, since the oil equalizing mode can be performed when the sensing value of some of the oil sensors is smaller than the reference value, it is prevented that the oil equalizing mode is performed unnecessarily, .

On the other hand, if it is determined in step S2 that the detected values of all the oil sensors are smaller than the reference value, it is determined that the oil of each of the compressors is insufficient, so that the oil recovery operation can be performed. That is, the expansion device of the indoor unit is opened, the respective compressors are operated at the maximum rotation frequency, and the oil accumulated in the indoor unit or the refrigerant pipe of the air conditioner can be recovered.

3 is a partial configuration diagram of the refrigerant cycle of the air conditioner according to the second embodiment.

The present embodiment is the same as the first embodiment in the other parts, except that the connection positions of the common pipes are different. Therefore, only the characteristic parts of the present embodiment will be described below, and the same parts as those of the first embodiment will be used as the first embodiment.

4, the common pipe 41 according to the present embodiment is connected to the accumulator 10

. Therefore, the oil of the common pipe 41 is introduced into the accumulator 10 and then moved to the common suction pipe 30 together with the oil stored in the accumulator 10.

Here, the oil stored in the accumulator 10 refers to the oil discharged from the evaporator and introduced into the accumulator 10. That is, the oil not separated by the oil separators 21 and 22 flows into the accumulator 10 via the condenser, the expander, and the evaporator together with the refrigerant.

The oil introduced into the accumulator 10 through the common pipe 41 is higher in temperature than the liquid refrigerant and oil stored in the accumulator 10 and is stored in the accumulator 10, The temperature is lowered by the low-temperature liquid refrigerant and the oil.

As described above, the high-temperature oil recovered from some compressors is first lowered in temperature by the decompression portions 44 and 45, and the temperature is lowered secondarily in the accumulator 10, The temperature of the low-temperature refrigerant sucked into the compressors (11, 12) can be prevented from rising.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. That is, within the scope of the present invention, all of the components may be selectively coupled to one or more of them. Furthermore, the terms "comprises", "comprising", or "having" described above mean that a component can be implanted unless otherwise specifically stated, But should be construed as including other elements. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used terms, such as predefined terms, should be interpreted to be consistent with the contextual meanings of the related art, and are not to be construed as ideal or overly formal, unless expressly defined to the contrary.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

11, 12: compressor 13, 14: oil sensor
42, 43: Bypass piping

Claims (6)

A plurality of compressors;
A plurality of oil sensors provided in each of the plurality of compressors to sense an oil level;
A plurality of bypass piping through which the oil or refrigerant discharged from each of the plurality of compressors flows;
A common piping in which the plurality of bypass piping are connected and extended to the accumulator;
A valve installed in the common pipe for controlling the flow of oil or refrigerant; And
And a common suction pipe extending from the accumulator to the suction side of the plurality of compressors,
The operation of the valve is controlled based on the oil level sensed by the plurality of oil sensors,
The refrigerant and the oil flowing into the common pipe according to the operation of the valve are introduced into the accumulator and heat-exchanged with the low temperature liquid refrigerant and the oil stored in the accumulator,
And the gas-phase refrigerant and the oil that have undergone the heat exchange in the accumulator are introduced into the common suction pipe.
The method according to claim 1,
Wherein the valve is opened when an oil level sensed by some of the plurality of oil sensors is lower than a reference level. The method according to claim 1,
Further comprising: a depressurization unit installed in each of the plurality of bypass pipes,
The accumulator includes:
And the temperature of the refrigerant and the oil that have passed through the pressure-reducing section are lowered secondarily.
A bypass pipe connected to each of the plurality of compressors; a common pipe connected to each of the bypass pipes and extending to the accumulator; a valve installed in the common pipe for controlling the flow of oil or refrigerant; And a common suction pipe extending from the accumulator to the suction side of the plurality of compressors, the method comprising:
Detecting an oil level in an oil sensor provided in each of the plurality of compressors;
Comparing the oil level sensed by each oil sensor with a reference level; And
And opening the valve if the oil level sensed by some of the plurality of oil sensors as a result of the comparison is smaller than the reference level,
When the valve is opened, refrigerant and oil flowing into the common pipe are introduced into the accumulator and heat-exchanged with the low-temperature liquid refrigerant and the oil stored in the accumulator,
And the gaseous refrigerant and the oil that have undergone the heat exchange in the accumulator flow into the common suction pipe.
5. The method of claim 4,
And when the oil level sensed by each of the plurality of oil sensors is equal to or higher than a reference level, the valve is closed. 5. The method of claim 4,
Wherein the oil recovery operation for recovering the oil in the air conditioner to the plurality of compressors is performed when the oil level sensed by each of the plurality of oil sensors is smaller than the reference level.

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