HEAT PUMP SYSTEM FOR A VEHICLE

A heat pump system for a vehicle may improve the cooling and heating performance by cooling or heating a vehicle interior by using a single heat-exchanger, and employing a gas injection device configured to selectively operate in at least one selected mode for air-conditioning of the vehicle interior to increase the flow rate of the refrigerant. The heat pump system includes a compressor, a control valve, a first heat-exchanger, a first expansion valve, a vehicle interior heat-exchanger, a second expansion valve, a second heat-exchanger, a connection line, a chiller, a third expansion valve, and a gas injection device, where a flow rate of the refrigerant is controlled depending on at least one mode for adjusting a temperature of a vehicle interior or for adjusting a temperature of a heating element.