Patent Publication Number: US-2023158856-A1

Title: Heat pump system for vehicle

Description:
TECHNICAL FIELD 
     The present disclosure relates to a heat pump system for a vehicle and, in more detail, a heat pump system for a vehicle that easily changes various driving modes using a 4-way valve, an internal heat exchanger, an electric cooling water heater, an electric part cooling circuit, an external heat exchanger, two electronic expansion valves, etc., and has configuration in which only one internal heat exchanger, through which an air conditioning refrigerant flows, is disposed in an HVAC module. 
     BACKGROUND ART 
     An automotive air conditioning system is a system that is generally operated selectively for a cooling function that cools the interior of a vehicle and a heating function that heats the inside of a vehicle. Such an automotive air conditioning system of the related art is configured to cool the interior of a vehicle by taking heat from air, which flows outside an evaporator of a refrigerant cycle, using a refrigerant flowing through the evaporator and to heat the interior of a vehicle by heating air that flows outside a heater core that is disposed in an air conditioning case called an HVAC unit and through which an engine cooling water circulates. 
     However, in an electric vehicle without an engine, there is no high-temperature engine cooling water that is supposed to be supplied to a heater core, and accordingly, it is required to consider a refrigerant cycle that is operated in a totally different way from automotive air conditioning system in the related art. 
     As a system that is applied to another type of refrigerant cycle suitable for electric vehicles, a heat pump system that selectively performs heating and cooling functions by changing the flow path of a refrigerant has been recently spotlighted. For example, a system that includes an evaporator and an internal heat exchanger in an HVAC unit, cools interior air by expanding and supplying a refrigerant, which has passed through an external heat exchanger, to the evaporator in a cooling mode, heats interior air by opening an air channel connected to the internal heat exchanger and supplying a high-temperature refrigerant, which has passed through a compressor, to the internal heat exchanger in a heating mode is applied. However, since it is difficult to satisfy the demand for cooling using only a refrigerant cycle, a system including a separate PTC heater mounted in an HVAC unit is representative. 
     That is, two heat exchangers (an internal heat exchanger and an evaporator installed in an HVAC unit and functioning as heaters) and a PCT heater that are disposed in an HVAC module, and a switch valve that can change the flow direction of a refrigerant are necessary components of the system. 
     Various types have been proposed for such a heat pump system for a vehicle, and representatively, there is Korean Patent No. 1316355. 
     An air conditioning system for an electric vehicle that uses the heat pump disclosed in Korean Patent No. 1316355, as shown in  FIG.  1   , includes: a cooling-heating unit in which an external heat exchanger  11 , a first expansion valve  12 , an evaporator  13 , a compressor  14 , an internal heat exchanger  25 , and a second expansion valve  53  are connected through a refrigerant channel and a first 3-way valve  51  controlling inflow of a refrigerant into the evaporator  13  is disposed at the upstream side of the first expansion valve  12 ; and an electric part cooling unit that connects electric parts and an electric part radiator through a cooling channel  35  and circulates cooling water using a water pump. The air conditioning system includes an evaporator  42  disposed in the electric part cooling channel  35 , a condenser  41  disposed in the refrigerant channel  16 , a loop-type heat pipe  43  connected to the evaporator  42  and the condenser  41  for circulation, and a channel control valve  54  installed in parallel with the second expansion valve  53  and controlling a refrigerant flowing to the second expansion valve  53 , in which when the channel control valve  54  is closed and the first 3-way valve  51  forms a channel such that a refrigerant flows through the external heat exchanger  11 , the first 3-way valve  51 , the compressor  14 , the internal heat exchanger  25 , and the second expansion valve  53  in the cooling-heating unit, the refrigerant that has passed through the second expansion valve is heated while the refrigerant in the loop-type heat pipe circulates through the evaporator  42  and the condenser  41 . 
     According to the heat pump system having the configuration described above in the related art, when the heating mode is operated, the first 3-way valve  51  is operated such that the refrigerant that has passed through the external heat exchanger  11  flows to the compressor  14  rather than the first expansion valve  12  and the evaporator  13 , and a blade  23  that has closed the internal heat exchanger  25  is opened such that air suctioned inside by a blower is heated by the internal heat exchanger  25  and the PTC heater  24 . Further, when the cooling mode is operated, the first 3-way valve  51  is operated such that the refrigerant that has passed through the external heat exchanger  11  flows to the first expansion valve  12  and the evaporator  13 , and the blade  23  that has closed the internal heat exchanger  25  is closed such that air suctioned inside by a blower is cooled by the evaporator  13 . 
     According to the heat pump system for an electric vehicle in the related art, in the heating mode, the internal heat exchanger  25  installed in the HVAC unit or an air conditioning case  21  performs heating by functioning as a condenser and the external heat exchanger  11  exchanges heat with external air by functioning as an evaporator outside the air conditioning case  21 , that is, at the front of a vehicle. In this process, when the external air temperature is low, the internal heat exchanger  25  that functions as a heater is not increased up to an appropriate temperature for heating because the external heat exchanger  11  exchanges heat with cold external air, so heat for heating is not sufficiently supplied. Accordingly, when the external air temperature is low, the heating performance is deteriorated or operation of a heat pump mode system is impossible, so the PTC heater  24  should be unavoidably added in the HVAC unit. 
     However, there is a need for an effort at the level of generally redesigning the HVAC module to add a separate component, such as a PTC heater, in an HVAC unit that is greatly limited in terms of freedom of design because it is installed in an instrument panel having a narrow package space. In particular, when internal combustion engine vehicles, hybrid vehicles, and electric vehicles of single models are each produced in a large quantity, there is a problem that it is required to develop a new HVAC module for an electric vehicle that is different from the HVAC module developed for an internal combustion engine vehicle. 
     Accordingly, there is a need for a technology of heat pump system for a vehicle in order to solve the problem in the related art. 
     PRIOR ART DOCUMENT 
     Patent Document 
     (Patent Document 1) Korean Patent No. 1316355 (published on Oct. 8, 2013) 
     DISCLOSURE 
     Technical Problem 
     An objective of the present disclosure is to provide a heat pump system that can easily change various driving mode using a 4-way valve, an internal heat exchanger, an electric cooling water heater, an electric part cooling circuit, an external heat exchanger, two expansion valves, etc., and that makes it possible to simplify pipelines and devices for various air conditioning modes so that an HVAC module for an internal combustion engine vehicle including a heater core and an evaporator, which use waste heat from an engine, in the related art can be used as an HVAC module for an electric vehicle that includes a heater core and an internal heat exchanger that are supplied with a cooling water heated by an electric cooling water heater, thereby enabling the HVAC module for an internal combustion engine vehicle in the related art to be used also as an HVAC for an electric vehicle and being able to improve heating efficiency and battery operation performance. 
     Technical Solution 
     In order to achieve the objectives, a heat pump system according to an aspect of the present disclosure may include: a compressor configured to compress and discharge a refrigerant; a 4-way valve configured to transmit a refrigerant, which is discharged from the compressor, to an external heat exchanger or an internal heat exchanger, depending on air conditioning modes; the external heat exchanger configured to enable a refrigerant transmitted from the compressor or the internal heat exchanger to exchange heat with air outside a vehicle; the internal heat exchanger configured to enable a refrigerant transmitted from the external heat exchanger to exchange heat with air that is supplied into an HVAC unit or enables a refrigerant discharged from the compressor to exchange heat with air that is supplied into the HVAC unit; an electric part cooling circuit mounted adjacent to the external heat exchanger configured to absorb and discharge heat, which is generated from electric parts mounted in a vehicle, to the outside through the electric part radiator or configured to absorb heat and then perform heat exchange with the refrigerant/electric part cooling water heat exchanger, depending on the air conditioning modes; the refrigerant/electric part cooling water heat exchanger mounted between the external heat exchanger and the 4-way valve and configured to enable heat exchange between a refrigerant that is discharged from the external heat exchanger and cooling water that flows through an electric part cooling water channel; a first expansion device disposed in a refrigerant line going to or coming from the internal heat exchanger to be able to expand a refrigerant, depending on the air conditioning modes; and a battery chiller mounted between the external heat exchanger and the internal heat exchanger in the HVAC module and configured to enable a refrigerant discharged from the external heat exchanger to exchange heat with a battery and then to be transmitted to the internal heat exchanger. 
     In an embodiment of the present disclosure, the 4-way valve may have: a first port of the 4-way valve configured to function as a refrigerant inlet into which a refrigerant discharged from the compressor always flows regardless of the air conditioning modes; a second port of the 4-way valve 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 disposed in the HVAC unit; a third port of the 4-way valve 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 a fourth port 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. 
     In an embodiment of the present disclosure, the intermediate heat exchanger may be mounted between the external heat exchanger and the internal heat exchanger, and may transmit a refrigerant discharged from the external heat exchanger to the internal heat exchanger after heat exchange or may transmit a refrigerant discharged from the internal heat exchanger to the external heat exchanger after heat exchange. 
     In an embodiment of the present disclosure, the heat pump system may further include an accumulator mounted between the intermediate heat exchanger and the compressor and configured to transmit a refrigerant that has passed through the intermediate heat exchanger to the compressor. 
     In an embodiment of the present disclosure, the internal heat exchanger may include: a first port of the internal heat exchanger through which a refrigerant that has absorbed heat from air that is supplied into a vehicle is discharged or through which a refrigerant for providing heat to air that is supplied into a vehicle flows inside, depending on the air conditioning modes; and a second port of the internal heat exchanger through which a refrigerant that absorbs heat from air that is supplied into a vehicle flows inside or through which a refrigerant that has provided heat to air that is supplied into the vehicle is discharged, depending on the air conditioning modes. 
     In this case, when the internal heat exchanger is used as an evaporator, depending in the air conditioning modes, a refrigerant that has passed through the first expansion device may flow into the second port of the internal heat exchanger such that a refrigerant transmitted from the external heat exchanger expands through the first expansion device and exchanges heat with air that is supplied into a vehicle. 
     An Electronic Expansion Valve (EEV) that can control the amount of expansion of a refrigerant or can close a refrigerant channel is applied as the first expansion device. 
     Further, when the internal heat exchanger is used as a condenser, depending in the air conditioning modes, a refrigerant discharged from the compressor may flow into the first port of the 4-way valve such that the refrigerant discharged from the compressor expands and exchanges heat with air that is supplied into a vehicle. 
     In an embodiment of the present disclosure, the electric part cooling circuit may include: an electric part radiator mounted adjacent to the external heat exchanger and configured to enable a refrigerant flowing through the electric part cooling water channel to exchange heat with the external heat exchanger; an electric part cooling water channel configured to form the refrigerant/electric part cooling water heat exchanger and the electric part radiator into one cooling water channel, and equipped with an electric part cooler configured to absorb heat generated from electric parts mounted in a vehicle and an electric part cooling water circulation pump configured to generate flow of cooling water in one direction are mounted; an electric part cooling water bypass channel formed on the electric part cooling water channel such that cooling water that has passed through the electric part cooler directly flows to the electric part radiator without passing through the refrigerant/electric part cooling water heat exchanger; and an electric part cooling water 3-way valve mounted at a joint at which the electric part cooling water channel and the electric part cooling water bypass channel communicate with each other, and configured to selectively send cooling water, which has passed through the electric part cooler, to the electric part cooling water bypass channel or the refrigerant/electric part cooling water heat exchanger, depending on the air conditioning modes. 
     The heat pump system of the present disclosure includes a battery chiller dividing a refrigerant line connecting the external heat exchanger and the internal heat exchanger such that a refrigerant discharged from the external heat exchanger flows into a second expansion device to be able to cool a battery by expanding, depending on the air conditioning modes. 
     In this case, the second expansion device is mounted in a pipeline through which a refrigerant discharged from the external heat exchanger flows into the battery chiller, and a check valve for preventing backflow of a refrigerant is mounted in a pipeline through which a refrigerant is discharged from the battery chiller. 
     An on/off-type Electronic Expansion Valve (EEV) having a function of opening and closing a channel with a predetermined expansion ratio is applied as the second expansion device. 
     A battery chiller is configured to be able to cool a battery by expanding a refrigerant by dividing a refrigerant line, which connects the external heat exchanger and the internal heat exchanger, at a side of the external heat exchanger such that a refrigerant discharged from the external heat exchanger flows into the second expansion device, depending on the air conditioning modes. The battery chiller, which is a component mounted in a refrigerant distribution line connecting a second divergent point of the 4-way valve of a refrigerant line, which connects the third port of the 4-way valve and the compressor, and the first divergent point, can transmit a refrigerant discharged from the external heat exchanger  130  to the internal heat exchanger  140  after heat exchange, depending on the air conditioning modes. The second divergent point is positioned before the intermediate heat exchanger to further increase the degree of super heat and performance of the refrigerant coming out of the battery chiller. 
     In an embodiment of the present disclosure, the heat pump system may further include a heater core that is mounted in an air flow pipeline for supplying air into a vehicle and is supplied with cooling water heated by an electric cooling water heater to be able 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. 
     Advantageous Effects 
     As described above, since there are provided a 4-way valve, a compressor, an external heat exchanger, and an internal heat exchanger that perform specific functions, respectively, it is possible to provide a heat pump system that can easily change a cooling mode and a heating mode, simplify pipelines and devices for the cooling mode and the heating mode, and improve heating efficiency and battery operation performance. Further, it is possible to share an HVAC module for internal combustion engine vehicle and an HVAC module for electric vehicles. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG.  1    is a configuration diagram showing a heat pump system for a vehicle according to the related art. 
         FIG.  2    is a configuration diagram showing a heat pump system for a vehicle according to an embodiment of the present disclosure. 
         FIG.  3    is a schematic diagram showing flow of a refrigerant in a cooling mode of the heat pump system according to an embodiment of the present disclosure. 
         FIG.  4    is a schematic view showing the state in which flow of cooling water has been partially changed using a waste heat collector in the cooling mode of the heat pump system according to an embodiment of the present disclosure. 
         FIG.  5    is a schematic view showing flow of a refrigerant in a heating mode of the heat pump system according to an embodiment of the present disclosure. 
         FIG.  6    is a schematic view showing flow of a refrigerant in a dehumidifying mode of the heat pump system according to an embodiment of the present disclosure. 
         FIG.  7    is a schematic view showing flow of a refrigerant in an external heat exchanger-defrosting mode of the heat pump system according to an embodiment of the present disclosure. 
         FIG.  8    is a schematic view showing flow of a refrigerant in the cooling mode and battery cooling of the heat pump system according to an embodiment of the present disclosure. 
         FIG.  9    is a schematic diagram showing flow of a refrigerant only in battery cooling by fully closing a first expansion device and opening a second expansion device in the heat pump system according to an embodiment of the present disclosure. 
     
    
    
     BEST MODE FOR DISCLOSURE 
     Hereafter, a “heat pump for a vehicle” of the present disclosure is described in detail with reference to the accompanying drawings. The embodiments to be described are provided for those skilled in the art to easily understand the spirit of the present disclosure and the present disclosure is not limited thereto. The configurations shown in the accompanying drawings are provided to easily describe embodiments of the present disclosure and may be different from actual configurations. 
     Expression “including components”, which is “open” expression, simply means that there are the components and should not be construed as excluding additional components. 
     It is to be understood that when one element is referred to as being “connected to” or “coupled to” another element, it may be connected directly to or coupled directly to another element or be connected to or coupled to another element, having the other element intervening therebetween. 
     Expression “first”, “second”, etc. is used only to discriminate a plurality of components without limiting the orders of components or other features. In particular, expressions such as “first expansion device” and “second expansion device”, or “first port”, “second port”, “third port”, and “fourth port” are provided only to clearly discriminate components without limiting the orders of components or other features. 
     General configuration of a heat pump system for a vehicle of the present disclosure is described with reference to  FIG.  2   . 
       FIG.  2    shows the configuration of a heat pump system according to an embodiment of the present disclosure. 
     First, the configuration of a heat pump system for a vehicle according to an embodiment of the present disclosure is as follows. 
     A heat pump system  100  for a vehicle according to an embodiment of the present disclosure may include a compressor  110 , a 4-way valve  120 , an external heat exchanger  130 , an internal heat exchanger  140 , an electric part cooling circuit  160 , a first expansion device  170 , and a battery chiller  190  that are disposed at specific positions and perform specific functions. 
     In more detail, the compressor  110  is a component that compresses and then discharges a refrigerant and the 4-way valve  120  is a component that transmits a refrigerant, which is discharged from the compressor  110 , to the external heat exchanger  130  or the internal heat exchanger  140 , depending on air conditioning modes. 
     The external heat exchanger  130  is a component that enables a refrigerant transmitted from the compressor  110  or the internal heat exchanger  140  to exchange heat with air outside a vehicle. The internal heat exchanger  140  is a component that enables a refrigerant transmitted from the external heat exchanger  130  to exchange heat with air that is supplied into a vehicle or enables a refrigerant discharged from the compressor  110  to exchange heat with air that is supplied into a vehicle. The first expansion device  170  is a component that is disposed in a refrigerant line going to or coming from the internal heat exchanger  140  to be able to expand a refrigerant, depending on air conditioning modes. 
     The electric part cooling circuit  160  is a component that is mounted adjacent to the external heat exchanger  130  and that absorbs and discharges heat, which is generated from electric parts mounted in a vehicle, to the outside, depending on air conditioning modes. 
     As a part of the electric part cooling circuit  160 , a refrigerant/electric part cooling water heat exchanger  161  mounted between the external heat exchanger  130  and the 4-way valve  120  and enabling 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  is included. 
     Next, the 4-way valve  120  according to the present disclosure is a component including a first port  121 , a second port  122 , a third port  123 , and a fourth port  124  that guide flow of a refrigerant into specific directions. 
     The first port  121  of the 4-way valve  120  is a refrigerant inlet into which a refrigerant discharged from the compressor  120  always flows regardless of air conditioning modes. 
     The second port  122  of the 4-way valve  120  is a refrigerant inlet/outlet that selectively communicates with the first port and the third port, depending on air conditioning mode, and is connected to the internal heat exchanger  140  disposed in an HVAC unit. 
     The third port  123  of the 4-way valve is a refrigerant outlet that selectively communicates with the second port and the fourth port, depending on air conditioning modes, and is connected to an intermediate heat exchanger disposed at the upstream side of the compressor in flow of a refrigerant. 
     The fourth port  122  of the 4-way valve is a refrigerant inlet/outlet that selectively communicates with the first port and the third port, depending on air conditioning modes, and is connected to a refrigerant/electric part cooling water heat exchanger of the electric part cooling circuit. 
     According to the ports of the 4-way valves, the third port and the fourth port communicate with each other when the first port and the second port communicate with each other, and the second port and the third port communicate with each other when the first port and the fourth port communicate with each other. 
     Accordingly, a refrigerant discharged from the compressor is transmitted to the refrigerant/electric part cooling water heat exchanger  161  of the electric part cooling circuit  160  when the first port communicates with the fourth port in the 4-way valve; and a refrigerant that has passed through the refrigerant/electric part cooling water heat exchanger  161  of the electric part cooling circuit is transmitted to the intermediate heat exchanger  180  disposed at the upstream side of the compressor in flow of a refrigerant when the fourth port communicates with and the third port. 
     There are provided a first divergent point  181  at which refrigerants separate or join each other at the side of the external heat exchanger  130  in the 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 the side of the 4-way valve  120  in the refrigerant line  120  connecting the third port  123  of the 4-way valve  120  and the compressor  110 , and a battery chiller  190  is mounted in a separate refrigerant line connecting the first divergent point  181  and the second divergent point  182 , whereby the refrigerant discharged from the external heat exchanger  130  is sent into the second expansion device  191 , depending on air conditioning mode. Further, a check valve  192  for preventing backflow of a refrigerant is disposed in a pipeline through which a refrigerant is discharged from the battery chiller  190 . 
     The second divergent point  182  is positioned before an intermediate heat exchanger  180  to further increase the degree of super heat and performance of the refrigerant coming out of the battery chiller. 
     The intermediate heat exchanger  180 , which is a component that is additionally disposed between the first divergent point  182  and the internal heat exchanger  140  in the refrigerant line connecting the external heat exchanger  130  and the internal heat exchanger  140 , can transmit a refrigerant discharged from the external heat exchanger  130  to the internal heat exchanger  140  after heat exchange or can transmit a refrigerant discharged from the internal heat exchanger  140  to the external heat exchanger  130  after heat exchange. 
     The intermediate heat exchanger  180  according to an embodiment of the present disclosure, which is also referred to as an IHX in abbreviation, is provided for heat exchange between refrigerants that have passed and have not passed yet through the first expansion device  170  and the internal heat exchanger  140 , respectively. Depending on embodiments, the intermediate heat exchanger  180  may be a double-pipe shape heat exchanger including an outer pipeline for transmitting a refrigerant to the first expansion device  170  and an inner pipeline for transmitting a refrigerant to an accumulator  150  and the compressor  110 . A refrigerant having relatively high pressure and temperature flows through the outer pipeline connected to the first expansion device  170  and a refrigerant having relatively low pressure and temperature flows through the inner pipeline. 
     A heater core  103  that is supplied with cooling water heated by an electric cooling water heater  104  is mounted at the position of a heater core, which obtains heat from waste heat of an engine, of an HVAC module for an internal combustion engine vehicle in the related art. The heater core  103  is disposed in a channel for supplying air into a vehicle and is controlled to apply heat to air that is supplied into a vehicle in a heating mode, a dehumidifying mode, or a defrosting mode, the electric part cooling circuit  160  is controlled to operate when the air conditioning mode of the heat pump system is a heating mode or a cooling mode, and the refrigerant/electric part cooling water heat exchanger  161  is operated as a water cooling type condenser using electric part cooling water in the cooling mode and as an evaporator absorbing heat from electric parts in the heating mode. 
     According to an embodiment of the present disclosure, in an HVAC module for an internal combustion engine vehicle including a heater core to which engine cooling water is supplied in the related art, a heater core  103  that is supplied with a cooling water heated by the electric cooling water heater  104  can be directly installed at the position of the heater core, so it is possible too share an HVAC module for an internal combustion engine vehicle and an HVAC module for an electric vehicle and it is also possible to share the heater core. 
     Air conditioning modes of the heat pump system for a vehicle are described in detail hereafter. 
       FIGS.  3  to  7    are refrigerant circulation diagrams showing refrigerant circulation in a cooling mode, a heating mode, a dehumidifying mode, and a defrosting mode of the heat pump system according to an embodiment of the present disclosure. 
     First, a cooling mode shown in  FIG.  3    is described. 
     In a cooling mode, a refrigerant is controlled to flow in order of “compressor  110  - 4-way valve  120  -electric part cooling circuit  160  (the refrigerant/electric part cooling water heat exchanger  161  functioning as a water cooling type condenser) - external heat exchanger  130  (functioning as a condenser) - intermediate heat exchanger  180  - internal heat exchanger  140  (functioning as an evaporator) - 4-way valve  120  - accumulator  150  - compressor  110 ”. 
     In the cooling mode, the first port  121  communicates with the fourth port  124  and the second port  122  communicates with the third port  123  in the 4-way valve  120  such that the refrigerant discharged from the compressor  110  flows into the external heat exchanger  130  and the refrigerant discharged from the internal heat exchanger  140  flows into the compressor  110 . 
     The internal heat exchanger  140  according to the present disclosure is a component that enables a refrigerant transmitted from the external heat exchanger  130  to exchange heat with air that is supplied into a vehicle or enables a refrigerant discharged from the compressor  110  to exchange heat with air that is supplied into a vehicle, depending on air conditioning modes. To this end, the internal heat exchanger  140  according to the present disclosure has a first port  141  and a second port  142  of which the functions depend on air conditioning modes. In detail, the first port  141  of the internal heat exchanger is a part through which a refrigerant that has absorbed heat from air flowing in the HVAC unit is discharged or through which a refrigerant for providing heat to air that is supplied into a vehicle flows inside, depending on air conditioning modes. The second port  142  is a part through which a refrigerant that absorbs heat from air flowing in the HVAC unit flows inside or through which a refrigerant that has provided heat to air that is supplied into a vehicle is discharged. 
     As described above, the internal heat exchanger  140  functions as an evaporator when the air conditioning mode is a cooling mode, in which a refrigerant that has passed through the first expansion device  170  flows into the second port  142  of the internal heat exchanger  140  such that a refrigerant transmitted from the external heat exchanger  130  expands through the first expansion device  170  and exchanges heat with air that is supplied into a vehicle. 
     The accumulator  150 , which is a component mounted between the intermediate heat exchanger  180  and the compressor  110 , absorbs a refrigerant, which is discharged from the internal heat exchanger  140 , through the 4-way valve  120  and then transmits the refrigerant to the compressor  110 . 
     The electric part cooling circuit  160  can be operated when the air conditioning mode is a cooling mode, and in this case, the refrigerant/electric part cooling water heat exchanger  161  operates as a water cooling type condenser using electric part cooling water, thereby being able to further cool a refrigerant in the refrigerant/electric part cooling water heat exchanger  161 . Accordingly, it is possible to improve cooling performance. 
     The cooling mode shown in  FIG.  3    is an operation mode under an external air temperature condition that does not require battery cooling and the second expansion device is closed to prevent a refrigerant channel from which the refrigerant line connecting the external heat exchanger  130  and the intermediate heat exchanger  180  diverges from opening and to prevent a refrigerant from flowing to the battery chiller  190 . The case in which the cooling mode and battery cooling are simultaneously performed is described separately with reference to  FIG.  8   . 
     The cooling mode shown in  FIG.  3    is, as described above, an external air temperature condition that does not require battery cooling and shows an embodiment in which the temperature of electric part cooling water is a setting temperature (70 ~ 80 degrees) or less, and in this situation, since the temperature of electric part cooling water is lower than the setting temperature, cooling of electric parts is not influenced even though heat transfers from a refrigerant and electric part cooling water flows to the refrigerant/electric part cooling water heat exchanger  161  through a cooling water circulation pump  165 , an electric part cooler  164 , and an electric part cooling 3-way valve  166 . 
     Meanwhile, as shown in  FIG.  4   , it is possible to absorb and discharge heat, which is generated from electric parts mounted in a vehicle, to only an electric part radiator  163  using the electric part cooling circuit  160 . 
     The electric part cooling circuit  160  includes a refrigerant/electric part cooling water heat exchanger  161 , an electric part radiator  163 , an electric part cooling water channel  162 , an electric part cooling water bypass channel  167 , and an electric part cooling water 3-way valve  166 . 
     In detail, the electric part radiator  163 , which is a component mounted adjacent to the external heat exchanger  130 , discharges heat of cooling water that flows through the electric part cooling water channel  162 . In this configuration, it may be possible to promote heat dissipation by installing a separate cooling fan  168 , as shown in the figure. The electric part cooling water channel  162  forms the refrigerant/electric part cooling water heat exchanger  161  and the electric part radiator  163  into one cooling water channel, and the electric part cooler  164  that absorbs heat generated from electric parts mounted in a vehicle and the electric part cooling water circulation pump  165  that generates flow of cooling water in one direction are mounted in the electric part cooling water channel  162 . 
     The electric part cooling water bypass channel  167 , as shown in  FIG.  4   , is formed on the electric part cooling water channel  162  such that cooling water that has passed through the electric part cooler  164  directly flows to the electric part radiator  163  without passing through the refrigerant/electric part cooling water heat exchanger  161 . The electric part cooling water 3-way valve  166  mounted at the joint at which the electric part cooling water channel  162  and the electric part cooling water bypass channel  167  communicate with each other selectively sends cooling water, which has passed through the electric part cooler  164 , to the electric part cooling water bypass channel  167  or the refrigerant/electric part cooling water heat exchanger  161 , depending on air conditioning modes. 
     The case shown in  FIG.  4    shows that when the air conditioning mode is a cooling mode, the temperature of electric part cooling water is a setting temperature (70 ~ 80 degrees) or more, and electric part cooling water is sent to the refrigerant/electric part cooling water heat exchanger  161  that operates as a water cooling type condenser, the cooling water additionally receives heat from a refrigerant, so cooling of electric part is no longer expected, and accordingly, cooling water that has passed through the electric part cooler  164  is sent directly to the electric part radiator  163  through the electric part cooling water bypass channel  167  by operating the electric part cooling water 3-way valve  166   
     That is, the temperature value of the cooling water that has passed through the electric part cooler  164  is a setting temperature value or more, the electric part cooling water 3-way valve  166  guides flow of electric part cooling water to the electric part cooling water bypass channel  167  so that the cooling water that has passed through the electric part cooler  164  flows directly to the electric part radiator  163  without passing through the refrigerant/electric part cooling water heat exchanger  161 . The temperature value of the cooling water may be set as 70 ~ 80 degrees. 
     Meanwhile, cooling water that passes through the electric part cooling water channel  162  and the electric part cooling water bypass channel  167  may be cooling water to which an antifreeze solution is added unlike the refrigerant that is used in a refrigeration cycle. 
     Next, the heating mode of the present disclosure is described with reference to  FIG.  5   . 
     In the heating mode, a refrigerant is controlled to flow in order of “compressor  110  - 4-way valve  120  -internal heat exchanger  140  (functioning as a condenser) -external heat exchanger  130  (functioning as an evaporator) electric part cooling circuit  160  (the refrigerant/electric part cooling water heat exchanger  161  functioning as a water cooling type condenser) - 4-way valve  120  -accumulator  150  - compressor  110 ”. 
     The first port  121  communicates with the second port  122  and the third port  122  communicates with the fourth port  123  in the 4-way valve  120  such that the refrigerant discharged from the compressor  110  flows into the internal heat exchanger  140  and the refrigerant discharged from the external heat exchanger  130  flows into the compressor  110 . 
     As described above, when the air conditioning mode is the heating mode, the internal heat exchanger  140  functions as a condenser, and the refrigerant discharged from the compressor  110  flows into the first port  141  of the internal heat exchanger  140  such that the refrigerant discharged from the compressor  110  is condensed and exchanges heat with air that is supplied into a vehicle. 
     It is also possible to improve heating performance by operating the electric cooling water heater  104  so that heat can be applied to air that is supplied into a vehicle. As shown in the figures, a heater core is disposed in the HVAC unit, a cooling water line for circulation through the heater core is configured, and an electric cooling water heater  104 , a pump  105 , and a cooling water reservoir tank  106  are disposed in the cooling water line. 
     The accumulator  150  can absorb a refrigerant, which is discharged from the electric part cooling circuit  160 , through the 4-way valve  120  and then transmit the refrigerant to the compressor  110 . In the electric part cooling circuit  160 , the refrigerant discharged from the external heat exchanger  130  can absorb heat, which is generated by electric parts mounted in a vehicle, through heat exchange and the refrigerant that has absorbed heat can be transmitted to the accumulator  150  through the 4-way valve  120 . 
     The case in which the heating mode is operated, as described above, corresponds to wintertime, and in general, it is not required to cool a battery in this case, so the second expansion device  191  is closed to prevent a refrigerant from flowing to the battery chiller  190 . When it is required to cool a battery due to problems with the battery itself or the surroundings, a battery cooling mode to be described below in which only battery cooling is performed is entered, whereby battery cooling is performed and heating is performed by the electric cooling water heater. 
     In the heating mode, the electric part cooling circuit  160 , as shown in  FIG.  5   , includes the refrigerant/electric part cooling water heat exchanger  161  mounted between the external heat exchanger  130  and the 4-way valve  120 , the electric part radiator  163  mounted adjacent to the external heat exchanger  130 , and the electric part cooling water channel  162 . 
     The refrigerant/electric part cooling water heat exchanger  161  can enable a refrigerant discharged from the external heat exchanger  130  and electric part cooling water flowing through the electric part cooling water channel  162  to exchange heat with each other. The electric part cooling water channel  162  forms one refrigerant line connecting the refrigerant/electric part cooling water heat exchanger  161  and the electric part radiator  163 , and the electric part cooler  164  that absorbs heat generated from electric parts mounted in a vehicle and the electric part cooling water circulation pump  165  that generates flow of a refrigerant in one direction are mounted in the electric part cooling water channel  162 . 
     In this configuration, the electric part cooling water 3-way valve  166  guides cooling water, which has passed through the electric part cooler  164 , to the refrigerant/electric part cooling water heat exchanger  161  and simultaneously prevents cooling water, which has passed through the electric part cooler  164 , from flowing to the electric part cooling water bypass channel  167 . 
     Depending on case, the electric part cooling water 3-way valve  166  may guide electric part cooling water to the electric part cooling water bypass channel  167  such that the cooling water, which has passed through the electric part cooler  164 , directly flows to the electric part radiator  163  without passing through the refrigerant/electric part cooling water heat exchanger  161 . The reason is that it is possible to expect that the refrigerant/electric part cooling water heat exchanger  161  functions as an evaporator because there is no heat from electric parts when the temperature of electric part cooling water is very low such as when a vehicle that has been parked outside for a long time is started. 
     However, when a vehicle is being driven, heat is generated from electric parts, and the refrigerant/electric part cooling water heat exchanger  161  of the electric part cooling circuit  160  functions as an evaporator when a refrigerant flows into the electric part cooling circuit  160 , whereby a refrigerant reaches a relatively high temperature by absorbing heat from the electric parts and flows into the accumulator  150  and the compressor. Accordingly, the amount of heat that is generated from the internal heat exchanger  140  increases and heating performance is further improved. 
     Next, the dehumidifying mode of the present disclosure is described with reference to  FIG.  6   . 
     In the dehumidifying mode, a refrigerant is controlled to flow in order of “compressor  110  - 4-way valve  120  - electric part cooling circuit  160  (the refrigerant/electric part cooling water heat exchanger  161  functioning as a water cooling type condenser) - external heat exchanger  130  (functioning as a condenser) -intermediate heat exchanger  180  - internal heat exchanger  140  (functioning as an evaporator) - 4-way valve  120  -accumulator  150  - compressor  110 ”. 
     In this case, the ports of the 4-way valves communicate with each other in the same way as the cooling mode such that the refrigerant discharged from the compressor  110  flows into the external heat exchanger  130  through the electric part cooling circuit  160  and the refrigerant discharged from the internal heat exchanger  140   flows into the compressor  110  through the intermediate heat exchanger  180 . 
     The electric cooling water heater  104  is also operated to apply heat to air that is supplied into a vehicle. 
     As in this embodiment, when the air conditioning mode is the dehumidifying mode, the internal heat exchanger  140  functions as an evaporator and air flowing in the HVAC unit condenses on the surface of the internal heat exchanger  140  functioning as an evaporator, whereby moisture in the air is removed. 
     The refrigerant that has passed through the first expansion device  170  is controlled to flow into the second port  142  of the internal heat exchanger  140  such that the refrigerant transmitted from the external heat exchanger  130  expands through the first expansion device  170  and exchanges heat with air that is supplied into a vehicle. 
     The electric cooling water heater  104  described above, which is a component that supplies heated cooling water to the heater core  103  mounted in an air flow path in the HVAC unit to supply air into a vehicle, can apply heat to air that is supplied into a vehicle, if necessary, whereby it is possible to provide air at an appropriate temperature to a driver who wants only a dehumidifying function rather than a cooling function. 
     Further, the case in which the dehumidifying mode is operated may correspond to summertime, so the temperature of a battery may increase and battery efficiency may decrease. Accordingly, the refrigerant line connecting the external heat exchanger  130  and the intermediate heat exchanger  180  to each other is divided such that a refrigerant expands through the second expansion device  191  and the battery chiller  190  functions as an evaporator while the expanding refrigerant passes through the battery chiller  190 , thereby cooling the battery. 
     When the dehumidifying mode is operated but it is not required to cool a battery, the second expansion device is closed to prevent a refrigerant from passing through the battery. 
     The defrosting mode of the present disclosure is described with reference to  FIG.  7   . 
     In the defrosting mode, a refrigerant is controlled to flow in order of “compressor  110  - 4-way valve  120  -electric part cooling circuit  160  (the refrigerant/electric part cooling water heat exchanger  161  functioning as a water cooling type condenser) - external heat exchanger  130  (functioning as a condenser) - intermediate heat exchanger  180  - internal heat exchanger  140  (functioning as an evaporator) - 4-way valve  120  - accumulator  150  - compressor  110 ”. 
     In the defrosting mode, the ports of the 4-way valve  120  communicate with each other in the same way as the cooling mode such that the refrigerant discharged from the compressor  110  flows into the external heat exchanger  130  and the refrigerant discharged from the internal heat exchanger  140  flows into the compressor  110 . 
     The electric cooling water heater  104  is also operated to apply heat to air that is supplied into a vehicle. 
     When the air conditioning mode is the defrosting mode, as in this embodiment, the internal heat exchanger  140  functions as an evaporator and the external heat exchanger  130  functions as a condenser. That is, heat of interior air is absorbed through an evaporator and the heat is discharged through the external heat exchanger  130  in the HVAC unit, whereby it is possible to remove frost formed on the surface of the external heat exchanger  130  due to a continuous heating mode in wintertime. 
     In the defrosting mode, the refrigerant that has passed through the first expansion device  170  is controlled to flow into the second port  142  of the internal heat exchanger  140  such that the refrigerant transmitted from the external heat exchanger  130  can decrease in temperature by expanding through the first expansion device  170  and can decrease the temperature of air flowing in the HVAC unit by absorbing heat from the air. 
     The electric cooling water heater  104  described above, which is a component for supplying heated cooling water to the heater core  103  mounted in the HVAC, applies heat to air that is supplied into a vehicle, so it is possible to obtain air having an increased temperature by increasing the temperature of the air of which the temperature has decreased through the internal heat exchanger in the defrosting mode that is operated in wintertime. 
     The case in which the defrosting mode is operated corresponds to wintertime for which the outdoor temperature is low, and in this case, in general, it is not required to cool a battery, so the second expansion device  191  is closed to prevent a refrigerant from flowing. 
     When frost on the external heat exchanger  130  is sensed and the defrosting mode is operated, it is possible to stop operation of the cooling fan  168  and the electric part cooling water circulation pump  165  in order to increase the temperature of the refrigerant that is supplied to the external heat exchanger  130 , and it is possible to operate an internal/external air mode into an internal air mode or a partial external air (external air of 10 ~ 20%) state and circulate cooling water heated by the electric cooling water heater  104  into the HVAC module for the heating function. 
     Next, the case in which the cooling mode and the battery cooling mode of the present disclosure are simultaneously performed is described with reference to  FIG.  8   . 
     When the cooling mode and the battery cooling mode of the present disclosure are simultaneously performed, a refrigerant is controlled to flow in order of “compressor  110  - 4-way valve  120  - electric part cooling circuit  160  (the refrigerant/electric part cooling water heat exchanger  161  functioning as a water cooling type condenser) -external heat exchanger  130  (functioning as a condenser) -intermediate heat exchanger  180  - internal heat exchanger  140  (functioning as an evaporator) - 4-way valve  120  -accumulator  150  - compressor  110 ”. Further, some of the refrigerant distributed from the refrigerant line connecting the external heat exchanger  130  and the intermediate heat exchanger  180  to each other flows into the battery chiller  190  through the second expansion device  191  to cool a battery. 
     When the air conditioning mode is the cooling mode, the internal heat exchanger  140  functions as an evaporator. The refrigerant that has passed through the first expansion device  170  flows into the second port  142  of the internal heat exchanger  140  such that the refrigerant transmitted from the external heat exchanger  130  expands through the first expansion device  170  and exchanges heat with air that is supplied into a vehicle. The accumulator  150 , which is a component mounted between the intermediate heat exchanger  180  and the compressor  110 , receives a refrigerant, which is discharged from the internal heat exchanger  140 , through the 4-way valve  120  and then transmits the refrigerant to the compressor  110 . 
     When the cooling mode and the battery cooling mode of the air conditioning mode are simultaneously performed, as shown in  FIG.  7   , it may be possible to decrease the temperature of a battery by decreasing the temperature of the refrigerant discharged from the external heat exchanger  130  through expanding, using the battery chiller  190  disposed between the external heat exchanger  130  and the intermediate heat exchanger  140 . 
     A second expansion device  191  is mounted in the pipeline through which the refrigerant discharged from the external heat exchanger  130  flows into the battery chiller  190  such that the battery chiller  190  can function as an evaporator by expanding the refrigerant. A check valve  192  for preventing backflow of a refrigerant may be mounted in the pipeline through which a refrigerant is discharged from the battery chiller  190 . 
     The case in which the cooling mode is operated corresponds to summertime for which the outdoor temperature is high, and in this case, the temperature of a battery increases and the battery efficiency decreases. Accordingly, the second expansion device  191  is partially opened such that a refrigerant flows and expands, the expanding refrigerant cools the cooling water in a battery cooling/heating cooling water circuit while passing through the battery chiller  190  that functions as an evaporator, and the cooling water is circulated to a cooling plate of a battery pack, thereby preventing the battery pack from being overheated. In this case, the second expansion device  191  may be an electric opening/closing expansion valve or an electronic expansion valve. As for the valve, when the temperature of a battery or a battery pack increases higher than a second battery setting temperature, the electronic expansion valve  191  is opened such that the battery cooling mode is also operated, so an expanding refrigerant cools the cooling water in the 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. Further, when the temperature of a battery decreases lower than a first battery setting temperature with the cooling mode in operation, the electronic expansion valve  191  can be closed such that the battery cooling mode is not operated. 
     In an embodiment of the present disclosure, the first setting temperature and the setting temperature that are the reference for changing the battery cooling mode may be 30 ~ 35 degrees and 35 ~ 37 degrees, respectively. 
     Accordingly, the refrigerant that has condensed through the external heat exchanger  130  expands through the first expansion device  170  and the second expansion device  190  and then flow at a low temperature into the internal heat exchanger  140  and the battery chiller  190 , thereby being able to cool air flowing in the HVAC unit and cool a battery. 
     In particular, in the present disclosure, since a refrigerant is distributed at the first divergent point  181  right before entering the intermediate heat exchanger  181  and the refrigerants that have passed through the battery chiller join at the second divergent point  182  at which the refrigerants have passed through the 4-way valve after passing through the internal heat exchanger, a relatively less refrigerant flows into the intermediate heat exchanger  181  and exchanges heat therein, so the refrigerant flowing into the internal heat exchanger  140  flows into an expansion device at a low temperature, that is, in a well liquefied state. Further, it is possible to expect, from this difference, an operation effect of decreasing the reason of noise in the expansion device installed right before a front panel separates an engine room and a passenger room, adjacent to the HVAC module that is usually positioned in the interior of a vehicle. 
     Finally, the case in which only the battery cooling operation is performed by the heat pump system for a vehicle of the present disclosure is described. 
     When only the battery cooling operation is performed, a refrigerant is controlled to flow in order of “compressor  110  - 4-way valve  120  - electric part cooling circuit  160  (the refrigerant/electric part cooling water heat exchanger  161  functioning as a water cooling type condenser) -external heat exchanger  130  (functioning as a condenser) -second expansion device  191  - battery chiller  190  (functioning as an evaporator) - check valve  192  -intermediate heat exchanger  180  - accumulator  150  -compressor  110 ”. 
     In this case, the first expansion device  170  such as an electronic expansion valve is closed, thereby preventing a refrigerant from flowing to the internal heat exchanger  140  from the intermediate heat exchanger  180 . 
     Further, the second expansion device (EEV)  191  installed by dividing the refrigerant line connecting external heat exchanger  130  and the intermediate heat exchanger  180  to each other is opened (which means that a channel is opened with a set expansion ratio) such that the refrigerant discharged from the external heat exchanger  130  expands and flows into the battery chiller  190 . 
     In more detail, in the same way as the case in which the cooling mode and the battery cooling mode are simultaneously performed, as described above, an expanding refrigerant cools the cooling water in the battery cooling/heating cooling water circuit while passing through the battery chiller  190  that functions as an evaporator, the cooling water is circulated to a cooling plate of a battery pack, thereby preventing the battery pack from being overheated. In this case, the second expansion device  191  may be an electric opening/closing expansion valve or an electronic expansion valve. As for the valve, when the temperature of a battery or a battery pack increases higher than a second battery setting temperature, the electronic expansion valve  191  is opened such that the battery cooling mode is also operated, so an expanding refrigerant cools the cooling water in the 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. Further, when the temperature of a battery decreases lower than a first battery setting temperature with the cooling mode in operation, the electronic expansion valve  191  can be closed such that the battery cooling mode is not operated. In an embodiment of the present disclosure, the first setting temperature and the setting temperature that are the reference for changing the battery cooling mode may be 30 ~ 35 degrees and 35 ~ 37 degrees, respectively. 
     The heat pump system of the present disclosure, using this configuration, can prevent a refrigerant from flowing to the internal heat exchanger  140  in the HVAC unit and can apply a heat pump cycle only to the battery chiller, thereby being able to cool only a battery without operating an air conditioning system. 
     As described above, according to the heat pump system for a vehicle of the present disclosure, since there are provided a 4-way valve, a compressor, an external heat exchanger, and an internal heat exchanger that perform specific functions, respectively, it is possible to easily change air conditioning modes, simplify pipelines and devices for the air conditioning modes, respectively, and improve heating efficiency and battery operation performance. Further, it is possible to achieve all of the air conditioning modes described above even by installing a heater core  103  and an internal heat exchanger  140  that receive cooling water heated by an electric cooling water heater  104  in an HVAC unit. Accordingly, there is an effect that it is possible to use an HVAC module having two heat exchangers that was developed for internal combustion engine vehicles as an HVAC module for electric vehicles even without specifically changing a design. 
     Only a specific embodiment was described in the above detailed description. However, the present disclosure should not be construed as being limited to the specific type described above and should be understood as including all modifications, equivalents, and substitutes that are included in the spirit and scope of the present disclosure that are defined by claims. 
     
       
         
           
               
               
             
               
                 Description of Reference Numerals 
               
             
            
               
                   100 : 
                 heat pump system 
               
               
                   101 : 
                 HVAC module 
               
               
                   102 : 
                 blower fan) 
               
               
                   103 : 
                 heater core 
               
               
                   104 : 
                 electric cooling water heater 
               
               
                   105 : 
                 pump 
               
               
                   106 : 
                 cooling water reservoir tank 
               
               
                   110 : 
                 compressor 
               
               
                   120 : 
                 4-way valve 
               
               
                   121 : 
                 first port of 4-way valve 
               
               
                   122 : 
                 second port of 4-way valve 
               
               
                   123 : 
                 third port of 4-way valve 
               
               
                   124 : 
                 fourth port of 4-way valve 
               
               
                   130 : 
                 external heat exchanger 
               
               
                   140 : 
                 internal heat exchanger 
               
               
                   141 : 
                 first port of internal heat exchanger 
               
               
                   142 : 
                 second port of internal heat exchanger 
               
               
                   150 : 
                 accumulator 
               
               
                   160 : 
                 electric part cooling circuit 
               
               
                   161 : 
                 refrigerant/electric part cooling water heat exchanger 
               
               
                   162 : 
                 electric part cooling water channel 
               
               
                   163 : 
                 electric part radiator 
               
               
                   164 : 
                 electric part cooler 
               
               
                   165 : 
                 electric part cooling water circulation pump 
               
               
                   166 : 
                 electric part cooling water 3-way valve 
               
               
                   167 : 
                 electric part cooling water bypass channel 
               
               
                   168 : 
                 cooling fan 
               
               
                   170 : 
                 first expansion device 
               
               
                   180 : 
                 intermediate heat exchanger 
               
               
                   190 : 
                 battery chiller 
               
               
                   191 : 
                 second expansion device 
               
               
                   192 : 
                 check valve