Air conditioner

Abstract

An air conditioner which controls capacity of an outdoor heat-exchanger unit without an on-off valve that exhibits high pressure loss, which prevents accumulation of refrigerant in an outdoor heat-exchanger, and which maintains reliability of a compressor or refrigeration cycle. The air conditioner includes a first expansion valve on a liquid line of a first outdoor heat- exchanger, a second expansion valve on a liquid line of a second outdoor heat-exchanger, a first connection line to connect a suction line to one port of the first 4-way valve, the suction line connecting a suction port of the compressor and an indoor heat-exchanger unit, a second connection line to connect the suction line to one port of the second 4-way valve, and a check valve provided on the second connection line to allow flow of refrigerant only from the second 4-way valve to the suction line.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of Korean Patent Application No. 10-2012-0114473, filed on Oct. 15, 2012 in the Korean Intellectual Property Office and of Japanese Patent Application No. 2011-271481, filed on Dec. 12, 2011 in the Japanese Intellectual Property Office, the disclosures of which are incorporated herein by reference.BACKGROUND[0002]1. Field[0003]Embodiments of the present disclosure relate to an air conditioner which includes an outdoor heat-exchanger unit constructed by connecting a plurality of outdoor heat-exchangers in a row, capacity of the outdoor heat-exchanger unit being controllable during low-load operation.[0004]2. Description of the Related Art[0005]For example, when an air conditioner is operated under low-load operating conditions, i.e. during heating operation under low indoor air-conditioning load and high outside temperature conditions or cooling operation under low indoor air-conditioning load and low ou...

AI Technical Summary

Benefits of technology

[0009]It is an aspect of the present disclosure to provide an air conditioner which may control capacity of an outdoor heat-exchanger unit without using an on-off valve that exhibits high pressure loss, prevent accumulation of refrigerant in an outdoor heat-exchanger when the outdoor heat-exchanger is stopped, and maintain reliability of a compressor or refrigeration cycle.

[0013]With the above-described configuration, under low-load operating conditions, the second expansion valve is closed and the second 4-way valve is switched to connect the gas line of the second outdoor heat-exchanger to the suction port of the compressor so as to prevent refrigerant from flowing to the second outdoor heat-exchanger, which results in reduction in the capacity of the outdoor heat-exchanger unit. In this way, it may be possible to control capacity of the outdoor heat-exchanger unit without providing a refrigerant circuit with electronic on-off valves that exhibit high pressure loss, and to prevent deterioration in heating or cooling efficiency.

[0014]Although the electronic on-off valve is replaced by the two 4-way valves, no increase in cost occurs as compared to provision of a large-scale electronic valve because the 4-way valve is a member easy to restrict increase in cost even if the size thereof increases to prevent pressure loss.

[0015]As a result of providing the second connection line with the check valve to allow flow of refrigerant only from the second 4-way valve to the suction line, it may be possible to prevent the refrigerant from the suction line or the first connection line from accumulating in the second outdoor heat-exchanger through the second connection line even when the refrigerant is not directed to the second outdoor heat-exchanger, but directed to the first outdoor heat-exchanger. Accordingly, it may be possible to prevent abnormal increase in the discharge pressure of the compressor, or to prevent deterioration in the reliability of the compressor caused when a compression ratio is less than a predetermined value. Also, it may be possible to prevent deterioration in cooling performance due to accumulation of refrigerant in the second outdoor heat-exchanger when the second outdoor heat-exchanger is stopped.

[0016]As a detailed configuration to maintain a prescribed compression ratio by preventing excessive condensation capability of the outdoor heat-exchanger unit and reduction in the discharge pressure of the compressor during cooling operation in which indoor air-conditioning load is low and outside temperature is low, the air conditioner may further include a pressure meter to measure discharge pressure and suction pressure of the compressor, and a valve controller to control at least the second 4-way valve and the second expansion valve, and if a compression ratio that is a ratio of the discharge pressure to the suction pressure measured by the pressure meter is less than a predetermined compression ratio during cooling operation, the valve controller may switch the second 4-way valve such that the gas line of the second outdoor heat-exchanger is connected to the suction port of the compressor, and the valve controller may also close the second expansion valve.

[0017]To prevent a high-pressure protection circuit from stopping the compressor under conditions of excessive evaporation capability of the outdoor heat-exchanger unit and increased discharge pressure of the compressor during heating operation in which indoor air-conditioning load is low and outside temperature is high, the valve controller may close the second expansion valve if the discharge pressure measured by the pressure meter is greater than a predetermined value during heating operation.

Problems solved by technology

For example, when an air conditioner is operated under low-load operating conditions, i.e. during heating operation under low indoor air-conditioning load and high outside temperature conditions or cooling operation under low indoor air-conditioning load and low outside temperature, evaporation or condensation capability of an outdoor heat-exchanger excessively increases, causing problematic operation.

More specifically, if evaporation capability of the outdoor heat-exchanger excessively increases during heating operation under low-load operating conditions, discharge pressure of a compressor also excessively increases to exceed an upper limit thereof, which causes sudden shutdown of the compressor by a protective circuit.

On the other hand, if condensation capability of the outdoor heat-exchanger excessively increases during cooling operation under low-load operating conditions, discharge pressure of the compressor decreases and has only a slight difference from suction pressure of the compressor, which causes an inappropriate compression ratio and makes it difficult to maintain reliability of the compressor.

However, the conventional air conditioner constructed as described above may suffer from high pressure loss during flow of refrigerant due to the plurality of electronic on-off valves provided at front and rear sides of the respective outdoor heat-exchangers, thus deteriorating heating or cooling performance.

However, using a large-scale electronic on-off valve to reduce pressure loss may not be beneficial in terms of cost.

In addition, although it may be contemplated to reduce the number of electronic on-off valves, for example, by installing the electronic on-off valve only at the front or rear side of each outdoor heat-exchanger, this may cause accumulation of refrigerant in the outdoor heat-exchanger when the outdoor heat- exchanger is stopped, thus deteriorating the flow rate of refrigerant and cooling or heating performance.

With the above-described configuration, under low-load operating conditions, the second expansion valve is closed and the second 4-way valve is switched to connect the gas line of the second outdoor heat-exchanger to the suction port of the compressor so as to prevent refrigerant from flowing to the second outdoor heat-exchanger, which results in reduction in the capacity of the outdoor heat-exchanger unit.

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