Heat pump system for a vehicle

1 . A heat pump system for a vehicle, comprising:

a compressor configured to compress a refrigerant circulating the heat pump system;

a heat, ventilation, and air condition (HVAC) module including an internal condenser, an evaporator connected to the compressor via a refrigerant line, and an opening/closing door configured to adjust air having passed through the evaporator to be selectively introduced into the internal condenser based on a cooling mode or a heating mode of the vehicle;

a heat-exchanger connected to the internal condenser via the refrigerant line and configured to selectively condense or evaporate refrigerant introduced thereto by exchanging heat with ambient air based on an operation of a third expansion valve;

a first expansion valve provided in the refrigerant line between the heat-exchanger and the evaporator;

an accumulator provided in the refrigerant line between the evaporator and the compressor;

a first connection line including: a first end connected to the refrigerant line between the compressor and the internal condenser, and a second end connected to the accumulator;

a chiller provided in the first connection line, and configured to adjust a temperature of a coolant by exchanging heat between the refrigerant introduced into the first connection line and a selectively introduced coolant;

a second expansion valve provided in the first connection line between the chiller and the accumulator; and

a second connection line including: a first end connected to the first expansion valve, and a second end connected to the accumulator.

2 . The heat pump system of claim 1 ,

wherein the third expansion valve is provided in the refrigerant line between the internal condenser and the heat-exchanger; and

a third connection line including: a first end connected to the third expansion valve, and a second end connected to the refrigerant line between the heat-exchanger and the first expansion valve.

3 . The heat pump system of claim 2 , wherein the first expansion valve, the second expansion valve, and the third expansion valve are electronic expansion valves configured to selectively expand the refrigerant while controlling a flow of the refrigerant.

4 . The heat pump system of claim 2 , wherein, in a hot gas heating mode of a vehicle interior:

the refrigerant line connecting the first expansion valve and the evaporator and the refrigerant line connecting the evaporator and the accumulator are closed by an operation of the first expansion valve;

the first connection line is opened by an operation of the second expansion valve; and

the second connection line is opened by the operation of the first expansion valve.

5 . The heat pump system of claim 4 , wherein the third connection line is selectively opened and closed by an operation of the third expansion valve.

6 . The heat pump system of claim 5 , wherein, when the third connection line is opened:

the refrigerant line connecting the heat-exchanger and the third expansion valve is closed; and

the refrigerant line connecting the heat-exchanger and a second end of the third connection line is closed.

7 . The heat pump system of claim 5 , wherein, when the third connection line is closed:

the refrigerant line connecting the internal condenser and the heat-exchanger is opened by the operation of the third expansion valve; and

the refrigerant line connecting the heat-exchanger and the first expansion valve is opened.

8 . The heat pump system of claim 4 , wherein the first expansion valve is configured to expand the refrigerant supplied via the refrigerant line.

9 . The heat pump system of claim 4 , wherein the second expansion valve is configured to expand the refrigerant having passed through the chiller and flow the expanded refrigerant to the first connection line.

10 . The heat pump system of claim 4 , wherein the third expansion valve is configured to flow the refrigerant having passed through the internal condenser without expansion.

11 . The heat pump system of claim 4 , wherein:

a partial refrigerant, among the refrigerant discharged from the compressor, flows into the internal condenser along the refrigerant line; and

a remaining refrigerant, among the refrigerant discharged from the compressor, flows into the chiller along the first connection line.

12 . The heat pump system of claim 4 , wherein the chiller is connected to a battery module via a coolant line through which the coolant circulates.

13 . The heat pump system of claim 12 , wherein, when heating the battery module in the hot gas heating mode of the vehicle interior, the coolant circulates via the coolant line such that the coolant having exchanged heat with the refrigerant in the chiller is supplied to the battery module.

14 . The heat pump system of claim 2 , wherein, in a hot gas heating and dehumidifying mode of a vehicle interior:

the refrigerant line connecting the first expansion valve and the evaporator is opened by an operation of the first expansion valve;

the refrigerant line connecting the evaporator and the accumulator is opened;

the first connection line is opened by an operation of the second expansion valve; and

the second connection line is closed by the operation of the first expansion valve.

15 . The heat pump system of claim 14 , wherein, when the third connection line is opened by the third expansion valve:

the refrigerant line connecting the heat-exchanger and the third expansion valve is closed; and

the refrigerant line connecting the heat-exchanger and a second end of the third connection line is closed.

16 . The heat pump system of claim 14 , wherein, when the third connection line is closed by the third expansion valve:

the refrigerant line connecting the internal condenser and the heat-exchanger is opened by the operation of the third expansion valve; and

the refrigerant line connecting the heat-exchanger and the first expansion valve is opened.

17 . The heat pump system of claim 14 , wherein:

the first expansion valve is configured to expand the refrigerant supplied via the refrigerant line and flow the expanded refrigerant to the evaporator; and

the second expansion valve is configured to expand the refrigerant having passed through the chiller and flow the expanded refrigerant to the first connection line.

18 . The heat pump system of claim 14 , wherein the third expansion valve is configured to flow the refrigerant having passed through the internal condenser to the refrigerant line without expansion.

19 . The heat pump system of claim 1 , wherein the second expansion valve is disposed at a rear end of the chiller based on a flow direction of the refrigerant flowing along the first connection line such that the refrigerant having passed through the chiller is introduced.