CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a U.S. National Stage Application under 35 U.S.C. § 371 of PCT Application No. PCT/KR2018/001414, filed Feb. 1, 2018, which claims priority to Korean Patent Application No. 10-2017-0014470, filed Feb. 1, 2017, whose entire disclosures are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to an outdoor system of an air conditioner.

BACKGROUND ART

An air conditioner is a home appliance for keeping indoor air in the most suitable condition according to usage and purpose thereof. For example, the air conditioner makes a room cool in the summer and makes the room warm in the winter. In addition, the air conditioner may control the humidity of the room and make indoor air clean.

Specifically, the air conditioner performs a refrigeration cycle for compressing, condensing, expanding and evaporating refrigerant to perform heating or cooling operation of an indoor space.

Such an air conditioner may be roughly classified into a separate air conditioner in which an indoor unit and an outdoor system are separately installed and an integrated air conditioner in which an indoor unit and an outdoor system are installed in one cabinet. An indoor heat exchanger for exchanging heat with indoor air is disposed in the indoor unit and an outdoor heat exchanger for exchanging heat with outdoor air is disposed in the outdoor system.

At this time, a plurality of outdoor systems may be provided. Each of the plurality of outdoor systems includes a compressor and an outdoor heat exchanger.

In general, the plurality of outdoor systems is connected in parallel such that refrigerant is circulated in each outdoor system. That is, refrigerant does not flow between different outdoor systems.

However, in an outdoor environment in which an outdoor temperature is very low, the plurality of outdoor systems may be connected in series to compress refrigerant in multiple stages. In this regard, the following prior art documents were disclosed.

(1) Prior Art 1: Korean Registered Patent No. 10-1071409 registered on Sep. 30, 2011 and entitled “System for generating hot water and cold water using a two-stage heat pump cycle”

(2) Prior Art 2: Korean Registered Patent No. 10-1196505 registered on Oct. 25, 2012 and entitled “Heat pump using two-stage compressor”

In Prior Arts 1 and 2, it is possible to achieve a required pressure ratio when an outdoor temperature is very low, by compressing refrigerant in two stages through a plurality of outdoor systems.

However, two-stage compression suffers from serious deterioration in the capacity and efficiency of the air conditioner except for a special case where the outdoor temperature is very low. Accordingly, inefficient operation may be performed in an area other than a special area.

DISCLOSURE

Technical Problem

An object of the present invention devised to solve the problem lies in an air conditioner capable of being switched between one-stage compression and two-stage compression.

Another object of the present invention devised to solve the problem lies in an air conditioner capable of achieving the above-described object by additionally installing a refrigerant pipe in an existing outdoor system without a separate device.

Technical Solution

An outdoor system of an air conditioner includes at least one outdoor unit, wherein the at least one outdoor unit includes a compressor, an outdoor heat exchanger, a pair of two-stage compression lines extending to the outside of the outdoor unit, a pair of connection lines extending to the outside of the outdoor unit to enable communication with an indoor unit, and a plurality of valves configured to open and close the pair of two-stage compression lines and the pair of connection lines when the outdoor unit is driven in any one of a one-stage heating mode and a two-stage heating mode.

The outdoor unit may include a first outdoor unit including a first compressor, a first outdoor heat exchanger and a pair of first connection lines, and a second outdoor unit including a second compressor, a second outdoor heat exchanger and a pair of second connection lines, and the first outdoor unit and the second outdoor unit may communicate with each other through the pair of two-stage compression lines.

The pair of two-stage compression lines may include a first two-stage compression line, through which refrigerant passing through the second outdoor heat exchanger flows into the first outdoor unit and a second two-stage compression line, through which refrigerant passing through the first compressor flows into the second outdoor unit.

The pair of first connection lines may include a first heat exchanger input/output line, through which gaseous refrigerant flows, and a first outdoor connection line, through which liquid refrigerant flows, and the pair of second connection lines may include a second heat exchanger input/output line, through which gaseous refrigerant flows, and a first outdoor system connection line, through which liquid refrigerant flows.

The plurality of valves may close the pair of two-stage compression lines when the first outdoor unit and the second outdoor unit are driven in the one-stage heating mode, and close the first outdoor system connection line when the first outdoor unit and the second outdoor unit are driven in the two-stage heating mode.

The plurality of valves may include a main four-way valve disposed at an inlet side of the compressor, and an auxiliary four-way valve disposed at an outlet side of the compressor, and, when the outdoor unit is switched from any one of the one-stage heating mode and the two-stage heating mode to the other thereof, any one of the main four-way valve and the auxiliary four-way valve may be switched.

The outdoor unit may include a first outdoor unit including a first compressor, a first outdoor heat exchanger, a first main four-way valve and a first auxiliary four-way valve and a second outdoor unit including a second compressor, a second outdoor heat exchanger, a second main four-way valve and a second auxiliary four-way valve, and, when the outdoor unit is switched from any one of the one-stage heating mode and the two-stage heating mode to the other thereof, any one of the first auxiliary four-way valve and the second main four-way valve may be switched.

The pair of connection lines may include a heat exchanger input/output line, through which the outdoor heat exchanger and the indoor unit communicate with each other, and the at least one outdoor unit may further include an injection line configured to connect the heat exchanger input/output line with the compressor.

The injection line may include an injection expansion valve and an injection heat exchanger configured to exchange heat between the injection line, through which refrigerant expanded by the injection expansion valve flows, and the heat exchanger input/output line.

The at least one outdoor unit may further include a two-stage compression injection line configured to connect at least one of the pair of two-stage compression lines with the compressor.

Advantageous Effects

The air conditioner according to the embodiment of the present invention may have the following effects.

It is possible to provide an air conditioner capable of operating in various operation modes such as a one-stage heating mode and a two-stage heating mode as necessary.

In particular, generally, the one-stage heating mode is performed as the heating mode. However, when an outdoor air is very low, the two-stage heating mode may be performed.

Since an inner pipe is installed in an outdoor system without requiring a separate device, it is possible to efficiently utilize a space.

In addition, it is possible to divide and use outdoor systems, through separation of refrigerant pipes.

