HEAT PUMP SYSTEM FOR VEHICLE

摘要

The present invention relates to a heat pump system for a vehicle and more specifically, to a heat pump system for a vehicle which can defrost the frosting of an outdoor heat exchanger rapidly using a heat pump mode, not in an air conditioning mode, and thus can improve heating performance and can improve stability of the system, by defrosting the outdoor heat exchanger by installing a second heat expansion unit in front of the outdoor heat exchanger besides a first heat exchange unit installed in front of an evaporator, and installing a third heat expansion unit in front of a heat exchange unit on a bypass line, and then controlling the second expansion unit and the third expansion unit in order for a refrigerant circulating in a refrigerant circulation line to be expanded before being flowed into the heat exchange unit. The system can assure a heating heat source additionally by absorbing heat as performing dehumidification by supplying a part of an expanded refrigerant to the evaporator through the first expansion unit in case dehumidification is required in the defrosting mode. [Reference numerals] (AA) No expansion; (BB) Expansion