Heat pump system for vehicle

A heat pump system for a vehicle, comprising:

• a compressor (110) configured to compress and discharge a refrigerant;
• a 4-way valve (120) configured to transmit a refrigerant, which is discharged from the compressor (110), to an external heat exchanger (130) or an internal heat exchanger (140), depending on air conditioning modes;
• the external heat exchanger (130) configured to perform heat exchange between a refrigerant transmitted from the compressor (110) or the internal heat exchanger (140) and air outside the vehicle;
• the internal heat exchanger (140) configured to enable a refrigerant transmitted from the external heat exchanger (130) to exchange heat with air that is supplied into an HVAC unit or enables a refrigerant discharged from the compressor (110) to exchange heat with air that is supplied into the vehicle;
• an electric part cooling circuit (160) mounted adjacent to the external heat exchanger (130) and configured to absorb and discharge heat, which is generated from electric parts mounted in the vehicle, to the outside, depending on the air conditioning modes;
• a refrigerant/electric part cooling water heat exchanger (161) mounted between the external heat exchanger (130) and the 4-way valve (120) and configured to enable heat exchange between a refrigerant that is discharged from the external heat exchanger (130) and cooling water that flows through an electric part cooling water channel (162);
• and
• a first expansion valve (170) disposed in a refrigerant line going to or coming from the internal heat exchanger (140) to be able to expand a refrigerant, depending on the air conditioning modes,
• wherein the 4-way valve (120) has:
• a first port (121) of the 4-way valve configured to function as a refrigerant inlet into which a refrigerant discharged from the compressor (110) always flows regardless of the air conditioning modes:
• a second port (122) of the 4-way valve (120) that is a refrigerant inlet/outlet that selectively communicates with the first port and a third port, depending on the air conditioning mode, and is connected to the internal heat exchanger (140) disposed in the HVAC unit;
• the third port (123) of the 4-way valve (120) that is a refrigerant outlet that selectively communicates with the second port and a fourth port, depending on air conditioning modes, and is connected to the compressor in flow of a refrigerant;
• and
• the fourth port (124) of the 4-way valve that is a refrigerant inlet/outlet that selectively communicates with the first port and the third port, depending on the air conditioning modes, and is connected to the refrigerant/electric part cooling water heat exchanger (161),
• a first divergent point (181) at which refrigerants separate or join each other at a side of the external heat exchanger (130) in a refrigerant line connecting the external heat exchanger (130) and the internal heat exchanger (140) without the 4-way valve (120), and a second divergent point (182) at which refrigerants separate or join each other at a side of the 4-way valve (120) in a refrigerant line connecting the third port (123) of the 4-way valve (120) and the compressor (110) are provided,
• wherein a battery chiller (190) is mounted in a separate refrigerant line connecting the first divergent point (181) and the second divergent point (182), and a second expansion valve (191) is mounted in a pipeline through which a refrigerant discharged from the external heat exchanger (130) flows into the battery chiller (190), so the refrigerant discharged from the external heat exchanger (130) is sent into the second expansion valve (191) and cools a battery, depending on air conditioning mode, and a check valve (192) configured to prevent backflow of a refrigerant is disposed in a pipeline through which a refrigerant is discharged from the battery chiller (190),
• an intermediate heat exchanger (180) which is additionally disposed between the first divergent point (181) of a refrigerant line, which connects the external heat exchanger (130) and the internal heat exchanger (140), and the internal heat exchanger (140), wherein the intermediate heat exchanger (180) is provided for heat exchange between refrigerants that have passed and have not passed yet through the first expansion valve (170) and the internal heat exchanger (140), respectively, and the second divergent point (182) is positioned before the intermediate heat exchanger (180) to further increase the degree of super heat and performance of the refrigerant coming out of the battery chiller,
• a heater core (103) that is supplied with cooling water heated by an electric cooling water heater (104) and is mounted at a position of a heater core, which obtains heat from waste heat of an engine, of an existing HVAC unit for an internal combustion engine, wherein the heater core (103) is disposed in a channel configured to supply air into the vehicle and is controlled to apply heat to air that is supplied into the vehicle when the air conditioning mode is a heating mode, a dehumidifying mode, or a defrosting mode,
• the electric part cooling circuit (160) which is controlled to operate when the air conditioning mode of the heat pump system is the heating mode or a cooling mode, wherein the refrigerant electric part cooling water heat exchanger (161) of the electric part cooling circuit (160) is operated as a water cooled condenser using electric part cooling water in the cooling mode and as an evaporator absorbing heat from electric parts in the heating mode, an electric part cooling 3-way valve (166) is operated such that the electric part cooling water flows to the refrigerant/electric part cooling water heat exchanger (161) when temperature of the electric part cooling water is less than a set temperature, and the electric part cooling 3-way valve (166) is operated such that the electric part cooling water flows to an electric part cooling water bypass channel (167) rather than flowing to the refrigerant electric part cooling water heat exchanger (161) when temperature of the electric part cooling water is greater than the set temperature, wherein the set temperature is set to a value within a temperature range of 70˜80 degrees Celsius,
• wherein when temperature of a battery increases higher than a second battery setting temperature with the cooling mode in operation, the second expansion valve (191) is opened such that a battery cooling mode is also operated, so an expanding refrigerant cools cooling water in a battery cooling circuit while passing through the battery chiller (190) that functions as an evaporator and the cooling water is circulated to a cooling plate of the battery pack, thereby preventing the battery pack from being overheated,
• wherein when temperature of the battery decreases lower than a first battery setting temperature with the cooling mode in operation, the second expansion valve (191) is closed such that the battery cooling mode is not operated, and
• wherein when frost on the external heat exchanger (130) is sensed and the defrosting mode is operated, operation of a cooling fan (168) and the electric part cooling water circulation pump (165) is stopped in order to increase temperature of a refrigerant that is supplied to the external heat exchanger (130), and an internal/external air mode is operated into an internal air mode or a partial external air state, and cooling water heated by the electric cooling water heater (104) is circulated into the HVAC unit for a heating function.