| 主权项 |
1. An air-conditioning apparatus comprising: a refrigeration cycle in which a compressor that compresses a low pressure refrigerant and discharges a high pressure refrigerant, a first heat exchanger in which the refrigerant exchanges heat, first expansion devices that depressurize the refrigerant, and one or more second heat exchangers in which the refrigerant exchanges heat, are connected by refrigerant pipes; an injection pipe that circulates the refrigerant split off from a refrigerant flow path through which the refrigerant that has radiated in the first heat exchanger or the one or more second heat exchangers flows; a first refrigerant branching portion that divides the refrigerant from the refrigerant flow path when the refrigerant is flowing from the first heat exchanger to the first expansion devices; a second refrigerant branching portion that divides the refrigerant from the refrigerant flow path when the refrigerant is flowing from the first expansion devices to the first heat exchanger; a branching pipe that connects the first refrigerant branching portion and the second refrigerant branching portion, with the injection pipe connected thereto; a refrigerant flow switching device that switches a refrigerant flow path between when the first heat exchanger functions as a condenser and the high pressure refrigerant passes through the first heat exchanger, and when the first heat exchanger functions as an evaporator and the low pressure refrigerant passes through the first heat exchanger; and a third expansion device, installed at a position on the refrigeration cycle, that generates a medium pressure less than the high pressure existing inside the condenser and greater than the low pressure on a suction side of the compressor when the first heat exchanger functions as an evaporator; a first mixing device, installed on an inlet-side flow path of an expansion portion of the third expansion device and in a vicinity of the expansion portion, that mixes a gaseous refrigerant and a liquid refrigerant in a two-phase gas-liquid refrigerant; and a controller that carries out driving control of the compressor, wherein the injection pipe is connected to the compressor via a second expansion device that depressurizes the refrigerant flowing thereinto, a distance between the expansion portion of the third expansion device and the first mixing device is less than or equal to six times an inner diameter of a pipe for the inlet-side flow path of the expansion portion of the third expansion device, the controller is configured to control an injection quantity of refrigerant introduced into the compressor from the injection pipe by controlling an opening degree of the second expansion device, and the controller is further configured to introduce the refrigerant from the high-pressure side into the compressor when the first heat exchanger functions as a condenser, and introduces the refrigerant from the medium-pressure side into the compressor when the first heat exchanger functions as an evaporator. |
