HEAT PUMP SYSTEM FOR A VEHICLE

A heat pump system for a vehicle is capable of improving cooling and heating performance by applying a gas injection device selectively operating in an air conditioning mode of the vehicle interior to increase the flow rate of the refrigerant. The heat pump system is further capable of reducing the manufacturing cost and reducing the weight by using a single heat-exchanger configured to exchange heat between at least two refrigerants having different temperatures and states with each other for the entire system. By implementing the gas injection device, the total number of the components may be reduced.