Vehicle heating, ventilation and air conditioning system

Abstract

The invention provides a vehicle heating ventilation air conditioning system comprising a compressor; an internal condenser provided on the downstream side of the compressor; a water-cooled heat exchanger disposed on a downstream side of the internal condenser and configured to transfer heat between the refrigerant and the coolant circulating in the coolant system; an external heat exchanger disposed on a downstream side of the water-cooled heat exchanger and configured to transfer heat between the refrigerant and ambient air; a refrigerant heat exchanger configured to transfer heat between the refrigerant discharged from the water-cooled heat exchanger and the refrigerant discharged from the internal condenser; and a first control valve located between the water-cooled heat exchanger and the internal condenser and configured to allow the refrigerant discharged from the internal condenser to be guided to at least one of the water-cooled heat exchanger, the refrigerant heat exchanger, and the external heat exchanger.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on and claims the benefit of priority from Korean Patent Application No. 10-2023-0088445 filed on July 7, 2023 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. Technical Field

[0003] The present invention relates to a vehicle heating, ventilation and air conditioning (HVAC) system, and more particularly, to a vehicle HVAC system designed to utilize a refrigerant to improve heating performance and / or dehumidification performance, thereby improving the electrical efficiency of an electric vehicle. Background Art

[0004] With the increasing attention paid to energy efficiency and environmental issues, there is a need to develop environmentally friendly vehicles that can replace internal combustion engine vehicles. Such environmentally friendly vehicles are divided into electric vehicles driven by using fuel cells or electricity as a power source and hybrid vehicles driven by using an engine and a battery.

[0005] An electric vehicle or hybrid vehicle may include a heating, ventilation and air conditioning (HVAC) system for air conditioning in a passenger compartment. The HVAC system may be configured to heat and cool the air in the passenger compartment to ensure passenger comfort.

[0006] In order to ensure driving safety, electric vehicles or hybrid vehicles include a power electronic cooling system designed to keep the power electronic components of the power electronic system at an appropriate temperature, and a battery cooling system designed to keep the battery at an appropriate temperature. The power electronic cooling system can cool power electronic components such as electric motors, inverters, on-board chargers (OBCs), and low-voltage DC-DC converters (LDCs), so that the power electronic components are kept at their respective appropriate temperatures. The battery cooling system can cool the battery, so as to keep the battery at its appropriate temperature.

[0007] The refrigerant circulating in the HVAC system of the electric vehicle may absorb heat from the power electronics coolant circulating in the power electronics cooling system through the water-cooled heat exchanger and be evaporated.

[0008] However, when the ambient air temperature is relatively low (e.g., -20°C - -5°C), the temperature of the power electronics coolant will be relatively low, and accordingly, the refrigerant will not be able to fully absorb heat from the power electronics coolant. As a result, the evaporation of the refrigerant will be reduced, and the suction pressure of the compressor will drop below the threshold pressure. If the suction pressure of the compressor is lower than the threshold pressure, the efficiency of the compressor will decrease, and accordingly, the RPM of the compressor will decrease below the threshold RPM or the compressor will stop. Therefore, the coefficient of performance (COP) of the HVAC system will decrease. Since the passenger compartment cannot be heated by the refrigerant, but is heated only by the electric heater of the HVAC system, the electrical efficiency of the electric vehicle will be reduced.

[0009] In the HVAC system according to the related art, since the heat absorption of the refrigerant is reduced when the ambient temperature is relatively low, the evaporation amount of the refrigerant may be insufficient. Accordingly, since the RPM of the compressor is reduced or the compressor is stopped, heating the passenger compartment with the refrigerant may not be performed smoothly, and the passenger compartment may be heated by the electric heater, so that the electrical efficiency of the electric vehicle is reduced.

[0010] When the HVAC system is operated in a heating and dehumidification mode to simultaneously perform heating of the passenger compartment and dehumidification of the passenger compartment, the HVAC system can automatically control the temperature of the passenger compartment to reach the target temperature. When the temperature of the passenger compartment reaches the target temperature, the RPM of the blower can be relatively reduced, so that the flow rate of air blown into the passenger compartment can be relatively reduced. When the flow rate of air blown into the passenger compartment is reduced, the internal condenser of the HVAC system may not be able to fully release heat into the air, and accordingly, the condensation of the refrigerant in the internal condenser may be insufficient. If the refrigerant condenses insufficiently, the dehumidification of the passenger compartment may not be performed smoothly, so that fog will appear on the vehicle glass (windows, windshield), and the suction pressure of the compressor may rise to a threshold pressure or higher, so that the compressor may be forced to stop to protect the compressor. If the compressor is forced to stop, the electric heater will operate to heat the passenger compartment, so that the electrical efficiency of the electric vehicle will be reduced.

[0011] The above information described in the Background section is to help understanding the background of the present inventive concept and may contain technical concepts that do not constitute prior art known to those skilled in the art. Summary of the invention

[0012] The present invention aims to solve the above-mentioned problems arising in the prior art while completely maintaining the advantages achieved by the prior art.

[0013] One aspect of the present invention provides a vehicle heating, ventilation and air conditioning (HVAC) system designed to improve heating performance and / or dehumidification performance using a refrigerant, thereby increasing the electrical efficiency of an electric vehicle.

[0014] According to one aspect of the present invention, a vehicle HVAC system may include: a compressor; an internal condenser located on a downstream side of the compressor; a water-cooled heat exchanger located on a downstream side of the internal condenser, the water-cooled heat exchanger being configured to transfer heat between a refrigerant and a coolant circulating in a coolant system; an external heat exchanger located on a downstream side of the water-cooled heat exchanger, the external heat exchanger being configured to transfer heat between the refrigerant and ambient air; a refrigerant heat exchanger configured to transfer heat between refrigerant discharged from the water-cooled heat exchanger and refrigerant discharged from the internal condenser; and a first control valve located between the water-cooled heat exchanger and the internal condenser, the first control valve being configured to allow the refrigerant discharged from the internal condenser to be directed to at least one of the water-cooled heat exchanger, the refrigerant heat exchanger, and the external heat exchanger.

[0015] The refrigerant heat exchanger may include a first passage through which the refrigerant discharged from the water-cooled heat exchanger passes, and a second passage through which the refrigerant discharged from at least one of the internal condenser and the external heat exchanger passes.

[0016] The vehicle HVAC system may further include a first bypass line configured to allow at least a portion of the refrigerant exhausted from the interior condenser to be directed from an upstream point of the water-cooled heat exchanger to a downstream point of the exterior heat exchanger. The first bypass line may be fluidly connected to the second passage of the refrigerant heat exchanger.

[0017] The vehicle HVAC system may further include a second bypass line configured to allow at least a portion of the refrigerant exhausted from the interior condenser to be directed from a point upstream of the water-cooled heat exchanger to a point upstream of the exterior heat exchanger. The second bypass line may be fluidly connected to an inlet of the exterior heat exchanger.

[0018] The first control valve may include an inlet port in communication with the internal condenser, a first outlet port in communication with the water-cooled heat exchanger, a second outlet port in communication with the first bypass line, and a third outlet port in communication with the second bypass line.

[0019] The opening degree of the first outlet port may be adjusted based on the discharge pressure and the discharge temperature of the compressor.

[0020] The vehicle HVAC system may further include a third bypass line configured to allow at least a portion of the refrigerant exhausted from the water-cooled heat exchanger to be directed from an upstream point of the external heat exchanger to an upstream point of the compressor. The third bypass line may be fluidly connected to an inlet of the first passage of the refrigerant heat exchanger.

[0021] The vehicle HVAC system may further include a second control valve configured to allow refrigerant exhausted from the water-cooled heat exchanger to be directed to at least one of the external heat exchanger and the first passage of the refrigerant heat exchanger.

[0022] The second control valve may include: an inlet port in communication with the water-cooled heat exchanger; a first outlet port in communication with the external heat exchanger; and a second outlet port in communication with the third bypass line.

[0023] The vehicle HVAC system may further include a check valve located between the external heat exchanger and the second passage of the refrigerant heat exchanger. The check valve may be configured to allow refrigerant to flow from the external heat exchanger to the second passage of the refrigerant heat exchanger and prevent refrigerant from flowing back from the second passage of the refrigerant heat exchanger to the external heat exchanger.

[0024] The vehicle HVAC system may also include: a cooling-side expansion valve disposed on a downstream side of a second channel of the refrigerant heat exchanger; an evaporator disposed on a downstream side of the cooling-side expansion valve; a distribution line configured to allow at least a portion of the refrigerant discharged from the second channel of the refrigerant heat exchanger to be directed from an upstream point of the cooling-side expansion valve to a downstream point of the evaporator; and a battery cooler fluidically connected to the distribution line and thermally connected to the battery cooling system.

[0025] The vehicle HVAC system may further include a third control valve configured to allow refrigerant exhausted from the second passage of the refrigerant heat exchanger to be directed to at least one of the cooling-side expansion valve and the battery cooler.

[0026] The third control valve may include an inlet port in communication with the second passage of the refrigerant heat exchanger, a first outlet port in communication with the cooling-side expansion valve, and a second outlet port in communication with the distribution line.

[0027] The opening degree of the first outlet port may be adjusted based on the discharge pressure of the compressor.

[0028] The opening degree of the second outlet port may be adjusted based on the suction pressure of the compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other objects, features and advantages of the present invention will become more apparent through the following detailed description in conjunction with the accompanying drawings:

[0030] Figure 1 A vehicle heating, ventilation and air conditioning (HVAC) system according to an exemplary embodiment of the present invention is shown.

[0031] Figure 2 The flow of refrigerant when the vehicle HVAC system according to an exemplary embodiment of the present invention is operated in a heating mode is shown.

[0032] Figure 3 The flow of refrigerant when the vehicle HVAC system according to an exemplary embodiment of the present invention is operated in a heating enhancement mode or a heating intensification mode is shown.

[0033] Figure 4 shows the flow of refrigerant when the vehicle HVAC system according to an exemplary embodiment of the present invention operates in a heating and dehumidification mode; and

[0034] Figure 5 Flow of refrigerant is shown when the vehicle HVAC system according to an exemplary embodiment of the present invention is operated in a heating and dehumidification enhancement mode or in a heating and dehumidification enhanced mode. DETAILED DESCRIPTION

[0035] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals will be used throughout to represent the same or equivalent elements. In addition, detailed descriptions of known technologies associated with the present invention will be excluded to avoid unnecessarily obscuring the gist of the present invention.

[0036] Terms such as first, second, A, B, (a) and (b) can be used to describe the elements in the exemplary embodiments of the present invention. These terms are only used to distinguish one element from another element, and the inherent characteristics, order or sequence of the corresponding elements, etc. are not limited by these terms. Unless otherwise defined, all terms including technical or scientific terms used in this article have the same meaning as those of ordinary skill in the field to which the present invention belongs. Terms as defined in common dictionaries should be interpreted as having the same meaning as the contextual meaning in the relevant technical field, and should not be interpreted as having an ideal or overly formal meaning, unless clearly defined as having such a meaning in this application.

[0037] Reference Figure 1 , a vehicle heating, ventilation and air conditioning (HVAC) system according to an exemplary embodiment of the present invention may be configured to heat and cool the air in the passenger compartment of the vehicle through a phase change of a circulating refrigerant. The HVAC system may include a refrigerant circulation passage 30 and an HVAC housing 60 that allow the refrigerant to circulate therethrough. The refrigerant circulation passage 30 may be fluidly connected to the compressor 11, the interior condenser 12, the water-cooled heat exchanger 24, the exterior heat exchanger 13, the cooling-side expansion valve 14, and the evaporator 15. The refrigerant circulation passage 30 may allow the flow of the refrigerant to vary according to various operating modes of the vehicle thermal management system.

[0038] The compressor 11 may compress the refrigerant and enable the refrigerant to circulate. Specifically, the compressor 11 may be configured to compress the refrigerant received from the evaporator 15 and / or the battery chiller 25. The compressor 11 may include a compressor motor and a compression portion operated by the compressor motor. The refrigerant circulation passage 30 may be fluidly connected to the compression portion of the compressor 11.

[0039] The HVAC system may include an accumulator 16 disposed at an upstream side of the compressor 11. The accumulator 16 may be located between the evaporator 15 and the compressor 11, and the accumulator 16 may separate liquid refrigerant by the refrigerant received from the evaporator 15, preventing the liquid refrigerant from flowing into the compressor 11.

[0040] The interior condenser 12 may be configured to condense the refrigerant received from the compressor 11, and thus air passing through the interior condenser 12 may be heated by the interior condenser 12. As the air heated by the interior condenser 12 flows into the passenger compartment, the passenger compartment may be heated.

[0041] The water-cooled heat exchanger 24 may be disposed on the downstream side of the interior condenser 12. The water-cooled heat exchanger 24 may be thermally connected to the coolant system 50. The water-cooled heat exchanger 24 may be configured to transfer heat between the coolant circulating in the coolant system 50 and the refrigerant circulating in the refrigerant circulation path 30.

[0042] According to an exemplary embodiment, the coolant system 50 may be a power electronic cooling system configured to cool a power electronic component 52. The coolant system 50 may include a coolant circulation passage 51 through which a coolant circulates, a power electronic component 52 fluidly connected to the coolant circulation passage 51, a power electronic radiator 53 fluidly connected to the coolant circulation passage 51, and a pump 54. The power electronic component may be an electric motor, an inverter, and a power conversion component. The power electronic radiator 53 may be disposed adjacent to a front grille of the vehicle, and the coolant passing through the power electronic radiator 53 may be cooled by ambient air forcibly blown by a cooling fan. The power electronic component may have a coolant channel disposed inside or outside thereof, and the coolant may pass through the coolant channel. The coolant channel of the power electronic component may be fluidly connected to the coolant circulation passage 51.

[0043] The water-cooled heat exchanger 24 may include a first channel 24a fluidly connected to the refrigerant circulation passage 30 and a second channel 24b fluidly connected to the coolant circulation passage 51. When the temperature of the power electronic component increases, the coolant may absorb heat from the power electronic component, so that the temperature of the coolant may be relatively increased. The refrigerant passing through the first channel 24a may absorb heat from the coolant passing through the second channel 24b, and thus the refrigerant may evaporate in the water-cooled heat exchanger 24.

[0044] The HVAC system according to the exemplary embodiment of the present invention may further include a receiver dryer 19 disposed at the downstream side of the water-cooled heat exchanger 24. The receiver dryer 19 may absorb moisture contained in the refrigerant discharged from the water-cooled heat exchanger 24 and store it to smoothly supply the refrigerant. The receiver dryer 19 may be adjacent to an outlet of the first channel 24a of the water-cooled heat exchanger 24.

[0045] The external heat exchanger 13 may be disposed on the downstream side of the first channel 24a of the water-cooled heat exchanger 24. The external heat exchanger 13 may have a refrigerant channel disposed therein, and the refrigerant may pass through the coolant channel. The external heat exchanger 13 may be disposed adjacent to the front grille of the vehicle, and the external heat exchanger 13 may be exposed to the outside. The external heat exchanger 13 may be configured to transfer heat between the refrigerant and the ambient air. During the cooling (refrigeration) operation of the HVAC system, the external heat exchanger 13 may be configured to condense the refrigerant received from the internal condenser 12. That is, the external heat exchanger 13 may be used as an external condenser, which condenses the refrigerant by allowing the refrigerant to release heat to the ambient air during the cooling operation of the HVAC system. During the heating (heating) operation of the HVAC system, the external heat exchanger 13 may be configured to evaporate the refrigerant received from the water-cooled heat exchanger 24. That is, the external heat exchanger 13 may be used as an external evaporator, which evaporates the refrigerant by allowing the refrigerant to absorb heat from the ambient air during the heating operation of the HVAC system. Specifically, the external heat exchanger 13 may perform heat exchange with the ambient air forcibly blown by the cooling fan, so that the heat transfer rate between the refrigerant and the ambient air may be further increased.

[0046] The HVAC system according to an exemplary embodiment of the present invention may include a refrigerant heat exchanger 26 disposed on the upstream side of the compressor 11. The refrigerant heat exchanger 26 may be configured to transfer heat between the refrigerant discharged from the first channel 24a of the water-cooled heat exchanger 24 and / or the evaporator 15 and the refrigerant discharged from the external heat exchanger 13 and / or the internal condenser 12. The refrigerant heat exchanger 26 may include a first channel 26a through which the refrigerant discharged from the evaporator 15 and / or the first channel 24a of the water-cooled heat exchanger 24 passes; and a second channel 26b through which the refrigerant discharged from the external heat exchanger 13 and / or the internal condenser 12 passes. The first channel 26a and the second channel 26b may be fluidly separated from each other.

[0047] The inlet of the first channel 26a may be located at the downstream side of the first channel 24a of the water-cooled heat exchanger 24 and the outlet of the evaporator 15, and thus the refrigerant discharged from the first channel 24a of the water-cooled heat exchanger 24 and the outlet of the evaporator 15 may be guided to the inlet of the first channel 26a.

[0048] An outlet of the first passage 26 a may be located at an upstream side of the compressor 11 , and thus refrigerant discharged from the outlet of the first passage 26 a may be guided to an inlet of the compressor 11 .

[0049] The inlet of the second passage 26b may be located at the downstream side of the outlet of the exterior heat exchanger 13 and the first bypass line 41, and thus the refrigerant discharged from the exterior heat exchanger 13 and / or the interior condenser 12 may be guided to the inlet of the second passage 26b.

[0050] The outlet of the second passage 26 b may be located on the upstream side of the cooling-side expansion valve 14 , and thus the refrigerant discharged from the outlet of the second passage 26 b may be guided to the inlet of the cooling-side expansion valve 14 .

[0051] The refrigerant heat exchanger 26 may be configured to transfer heat between the refrigerant passing through the first passage 26a and the refrigerant passing through the second passage 26b. The temperature of the high-pressure refrigerant discharged from the interior condenser 12 may be higher than the temperature of the low-pressure refrigerant discharged from the first passage 24a of the water-cooled heat exchanger 24. Therefore, the refrigerant passing through the first passage 26a may absorb heat from the refrigerant passing through the second passage 26b.

[0052] The HVAC system according to the exemplary embodiment of the present invention may further include a distribution line 45 configured to allow at least a portion of the refrigerant discharged from the second passage 26 b of the refrigerant heat exchanger 26 to be guided from an upstream point of the cooling-side expansion valve 14 to a downstream point 38 a of the evaporator 15 .

[0053] The distribution line 45 may connect a point between the outlet of the external heat exchanger 13 and the inlet of the cooling side expansion valve 14 to a point 38a between the outlet of the evaporator 15 and the inlet of the compressor 11. Specifically, the inlet of the distribution line 45 may be connected to the refrigerant circulation passage 30 between the second passage 26b of the refrigerant heat exchanger 26 and the inlet of the cooling side expansion valve 14, and the outlet of the distribution line 45 may be connected to the refrigerant circulation passage 30 between the outlet of the evaporator 15 and the first passage 26a of the refrigerant heat exchanger 26. At least a portion of the refrigerant discharged from the external heat exchanger 13 may bypass the cooling side expansion valve 14 and the evaporator 15 through the distribution line 45, and be guided to the compressor 11. That is, the distribution line 45 may be configured to allow at least a portion of the refrigerant discharged from the external heat exchanger 13 to bypass the cooling side expansion valve 14 and the evaporator 15.

[0054] The battery cooler 25 may be fluidly connected to the distribution line 45, and the battery cooler 25 may be configured to transfer heat between the distribution line 45 and a battery cooling system (not shown). The battery cooling system may be configured to allow circulation of a coolant that exchanges heat with the battery. The battery cooler 25 may be configured to transfer heat between a refrigerant passing through the distribution line 45 and a coolant circulating in the battery cooling system. That is, the battery cooler 25 may be thermally connected to the battery cooling system and the distribution line 45.

[0055] The battery cooler 25 may include a first channel fluidly connected to the distribution line 45 and a second channel fluidly connected to a battery coolant circulation passage of the battery cooling system. According to an exemplary embodiment, the battery cooler 25 may be configured to transfer heat between the refrigerant passing through the first channel of the battery cooler 25 and the battery coolant passing through the second channel of the battery cooler 25. The refrigerant may absorb heat from the battery coolant so that the refrigerant may evaporate, and the battery coolant may release heat to the refrigerant so that the battery coolant may be cooled.

[0056] The cooling side expansion valve 14 may be disposed on the downstream side of the external heat exchanger 13 and the second passage 26b of the refrigerant heat exchanger 26, and the cooling side expansion valve 14 may be disposed between the second passage 26b of the refrigerant heat exchanger 26 and the evaporator 15 in the refrigerant circulation passage 30. The cooling side expansion valve 14 may be disposed on the upstream side of the evaporator 15, and regulates the flow of the refrigerant entering the evaporator 15 and / or the flow rate of the refrigerant. During the cooling operation of the HVAC system, the cooling side expansion valve 14 may be configured to expand the refrigerant received from the external heat exchanger 13. According to an exemplary embodiment, the cooling side expansion valve 14 may be a thermal expansion valve (TXV) that senses the temperature and / or pressure of the refrigerant and regulates the opening degree of the cooling side expansion valve 14.

[0057] The evaporator 15 may be provided on the downstream side of the cooling-side expansion valve 14, and receive the refrigerant expanded by the cooling-side expansion valve 14. The evaporator 15 may be configured to cool the air using the refrigerant received from the cooling-side expansion valve 14. That is, the refrigerant expanded by the cooling-side expansion valve 14 may absorb heat from the air and evaporate in the evaporator 15. During the cooling operation of the HVAC system, the evaporator 15 may be configured to cool the air using the refrigerant cooled by the external heat exchanger 13 and expanded by the cooling-side expansion valve 14, and the air cooled by the refrigerant may be guided into the passenger compartment.

[0058] The HVAC system according to an exemplary embodiment of the present invention may include a low-pressure refrigerant sensor 17 disposed at an upstream side of the compressor 11 and adjacent to an inlet of the compressor 11 , and a high-pressure refrigerant sensor 18 disposed at a downstream side of the compressor 11 and adjacent to an outlet of the compressor 11 .

[0059] The low-pressure refrigerant sensor 17 may sense the pressure and temperature of the low-pressure refrigerant flowing into the inlet of the compressor 11. That is, the low-pressure refrigerant sensor 17 may sense the suction pressure and suction temperature of the compressor 11. In addition, the superheat of the refrigerant may be determined based on the pressure and temperature of the low-pressure refrigerant sensed by the low-pressure refrigerant sensor 17. For example, the low-pressure refrigerant sensor 17 may be located between the inlet of the compressor 11 and the accumulator 16.

[0060] The high-pressure refrigerant sensor 18 may sense the pressure and temperature of the high-pressure refrigerant discharged from the outlet of the compressor 11. That is, the high-pressure refrigerant sensor 18 may sense the discharge pressure and discharge temperature of the compressor 11. For example, the high-pressure refrigerant sensor 18 may be located between the outlet of the compressor 11 and the interior condenser 12.

[0061] The HVAC housing 60 may have an inlet and an outlet, and the HVAC housing 60 may be configured to allow air to flow to the passenger compartment of the vehicle. The evaporator 15 and the interior condenser 12 may be located inside the HVAC housing 60. An air mixing door 61 may be provided between the evaporator 15 and the interior condenser 12, and an electric heater 62 such as a positive temperature coefficient (PTC) heater may be provided on the downstream side of the interior condenser 12 in the air flow direction.

[0062] The HVAC system according to the exemplary embodiment of the present invention may further include a first bypass line 41 configured to allow at least a portion of the refrigerant discharged from the interior condenser 12 to be guided from an upstream point of the first channel 24a of the water-cooled heat exchanger 24 to a point 36a downstream of the exterior heat exchanger 13. The first bypass line 41 may be fluidly connected to an inlet of the second channel 26b of the refrigerant heat exchanger 26. The first bypass line 41 may connect a point between the outlet of the interior condenser 12 and the inlet of the water-cooled heat exchanger 24 to the above-mentioned point 36a between the outlet of the exterior heat exchanger 13 and the inlet of the cooling side expansion valve 14. Therefore, the refrigerant passing through the first bypass line 41 may bypass the water-cooled heat exchanger 24 and the exterior heat exchanger 13, and be guided to the cooling side expansion valve 14. That is, the first bypass line 41 may be configured to allow at least a portion of the refrigerant discharged from the interior condenser 12 to bypass the water-cooled heat exchanger 24 and the exterior heat exchanger 13.

[0063] The HVAC system according to an exemplary embodiment of the present invention may further include a second bypass line 42 configured to allow at least a portion of the refrigerant discharged from the interior condenser 12 to be directed from an upstream point of the first channel 24a of the water-cooled heat exchanger 24 to an upstream point 34a of the exterior heat exchanger 13. The second bypass line 42 may be fluidly connected to an inlet of the exterior heat exchanger 13. The second bypass line 42 may connect a point between an outlet of the interior condenser 12 and the first channel 24a of the water-cooled heat exchanger 24 to a point between an inlet of the exterior heat exchanger 13 and the first channel 24a of the water-cooled heat exchanger 24. The refrigerant passing through the second bypass line 42 may bypass the first channel 24a of the water-cooled heat exchanger 24 and be directed to the exterior heat exchanger 13. That is, the second bypass line 42 may be configured to allow at least a portion of the refrigerant discharged from the interior condenser 12 to bypass the water-cooled heat exchanger 24.

[0064] The HVAC system according to an exemplary embodiment of the present invention may include a first control valve 21 located between the water-cooled heat exchanger 24, the interior condenser 12, the first bypass line 41, and the second bypass line 42. The first control valve 21 may be configured to control the flow of refrigerant (the direction of the refrigerant, the flow rate of the refrigerant, etc.) between the interior condenser 12, the first passage 24a of the water-cooled heat exchanger 24, the second passage 26b of the refrigerant heat exchanger 26, and the exterior heat exchanger 13. Specifically, the first control valve 21 may be configured to control the flow of the refrigerant in a manner that allows the refrigerant discharged from the interior condenser 12 to flow to at least one of the first passage 24a of the water-cooled heat exchanger 24, the second passage 26b of the refrigerant heat exchanger 26, and the exterior heat exchanger 13.

[0065] The first control valve 21 may include an inlet port 21a communicating with the interior condenser 12 , a first outlet port 21b communicating with the first passage 24a of the water-cooled heat exchanger 24 , a second outlet port 21c communicating with the first bypass line 41 , and a third outlet port 21d communicating with the second bypass line 42 .

[0066] The inlet port 21 a may receive the refrigerant exhausted from the interior condenser 12 .

[0067] The opening degree of the first outlet port 21b can be adjusted by the controller 100, so that the refrigerant can expand through the first outlet port 21b, and the flow rate of the refrigerant entering the water-cooled heat exchanger 24 can be adjusted. When the opening degree of the first outlet port 21b is adjusted, the refrigerant can expand at the first outlet port 21b, and the expanded refrigerant can be guided to the water-cooled heat exchanger 24.

[0068] According to an exemplary embodiment, the opening degree of the first outlet port 21b may be adjusted based on the pressure (discharge pressure of the compressor 11) and the temperature (discharge temperature of the compressor 11) of the high-pressure refrigerant sensed by the high-pressure refrigerant sensor 18. When the opening degree of the first outlet port 21b is adjusted to a predetermined degree, the refrigerant discharged from the first outlet port 21b may expand, and the pressure and temperature of the refrigerant discharged from the first outlet port 21b may decrease. Specifically, when the HVAC system is operated in a heating mode, the opening degree of the first outlet port 21b may be adjusted based on the discharge pressure and the discharge temperature of the compressor 11, so that the first outlet port 21b may be used as a heating-side expansion valve that expands the refrigerant guided to the water-cooled heat exchanger 24.

[0069] According to another exemplary embodiment, the opening degree of the first outlet port 21b may be adjusted based on the superheat of the refrigerant, and the controller 100 may determine the superheat of the refrigerant based on the pressure and temperature of the refrigerant sensed by the low-pressure refrigerant sensor 17. Specifically, when the opening degree of the first outlet port 21b is adjusted based on the pressure (suction pressure of the compressor 11) and temperature (suction temperature of the compressor 11) of the low-pressure refrigerant sensed by the low-pressure refrigerant sensor 17, the refrigerant discharged from the first outlet port 21b may expand, and the pressure and temperature of the refrigerant discharged from the first outlet port 21b may decrease. Specifically, when the HVAC system is operated in a heating mode, the opening degree of the first outlet port 21b may be adjusted so that the first outlet port 21b may be used as a heating-side expansion valve that expands the refrigerant guided to the water-cooled heat exchanger 24.

[0070] In addition, the first outlet port 21b may be fully opened or fully closed. When the first outlet port 21b is fully opened, the refrigerant may be guided to the water-cooled heat exchanger 24 without expanding.

[0071] The opening degree of the second outlet port 21c can be adjusted by the controller 100, and the inlet of the first bypass line 41 can be directly connected to the second outlet port 21c. The second outlet port 21c can be opened or closed by the controller 100 based on whether the HVAC system is operated in a heating boost mode or a heating enhanced mode. When the HVAC system is operated in the heating boost mode or the heating enhanced mode, the second outlet port 21c can be opened so that at least a portion of the refrigerant discharged from the interior condenser 12 can be guided to the first bypass line 41.

[0072] The inlet of the second bypass line 42 may be directly connected to the third outlet port 21 d, and the third outlet port 21 d may be opened or closed by the controller 100 based on whether the HVAC system is operated in the dehumidification enhancement mode or the dehumidification enhancement mode. When the HVAC system is operated in the dehumidification enhancement mode or the dehumidification enhancement mode, the third outlet port 21 d may be opened so that at least a portion of the refrigerant exhausted from the interior condenser 12 may be guided to the second bypass line 42.

[0073] The HVAC system according to the exemplary embodiment of the present invention may further include a third bypass line 43 configured to allow at least a portion of the refrigerant discharged from the first passage 24 a of the water-cooled heat exchanger 24 to be guided from an upstream point of the external heat exchanger 13 to an upstream point of the compressor 11 .

[0074] The third bypass line 43 may be fluidly connected to the first passage 26a of the refrigerant heat exchanger 26. The third bypass line 43 may connect a point between an outlet of the first passage 24a of the water-cooled heat exchanger 24 and an inlet of the external heat exchanger 13 to an upstream point 39a of the compressor 11. At least a portion of the refrigerant discharged from the first passage 24a of the water-cooled heat exchanger 24 may bypass the external heat exchanger 13 through the third bypass line 43.

[0075] The HVAC system according to an exemplary embodiment of the present invention may include a second control valve 22 located between the water-cooled heat exchanger 24, the external heat exchanger 13, and the third bypass line 43. The second control valve 22 may be configured to control the flow of refrigerant (the direction of the refrigerant, the flow rate of the refrigerant, etc.) between the first passage 24a of the water-cooled heat exchanger 24, the external heat exchanger 13, and the first passage 26a of the refrigerant heat exchanger 26. Specifically, the second control valve 22 may be configured to control the flow of the refrigerant in a manner that allows the refrigerant discharged from the first passage 24a of the water-cooled heat exchanger 24 to be guided to at least one of the external heat exchanger 13 and the first passage 26a of the refrigerant heat exchanger 26.

[0076] The second control valve 22 may include an inlet port 22a communicating with the water-cooled heat exchanger 24, a first outlet port 22b communicating with the external heat exchanger 13, and a second outlet port 22c communicating with the third bypass line 43. The second outlet port 22c may communicate with the first passage 26a of the refrigerant heat exchanger 26 through the third bypass line 43.

[0077] The second control valve 22 may be switched to allow the inlet port 22a to communicate with at least one of the first outlet port 22b and the second outlet port 22c. For example, when the second control valve 22 is switched to allow the inlet port 22a to communicate with the second outlet port 22c, the refrigerant discharged from the first passage 24a of the water-cooled heat exchanger 24 may be guided to the first passage 26a of the refrigerant heat exchanger 26 and the compressor 11 through the third bypass line 43. That is, the refrigerant may bypass the external heat exchanger 13 and circulate through the third bypass line 43. When the second control valve 22 is switched to allow the inlet port 22a to communicate with the first outlet port 22b, the refrigerant discharged from the water-cooled heat exchanger 24 may be guided to the external heat exchanger 13 without passing through the third bypass line 43.

[0078] The HVAC system may include a third control valve 23 located between the second passage 26b of the refrigerant heat exchanger 26, the cooling side expansion valve 14, and the distribution line 45. The third control valve 23 may be configured to control the flow of refrigerant (the direction of the refrigerant, the flow rate of the refrigerant, etc.) between the second passage 26b of the refrigerant heat exchanger 26, the cooling side expansion valve 14, and the battery cooler 25. Specifically, the third control valve 23 may control the flow of the refrigerant in a manner that allows the refrigerant discharged from the second passage 26b of the refrigerant heat exchanger 26 to be directed to at least one of the cooling side expansion valve 14 and the battery cooler 25.

[0079] The third control valve 23 may include an inlet port 23 a communicating with the second passage 26 b of the refrigerant heat exchanger 26 , a first outlet port 23 b communicating with the cooling-side expansion valve 14 , and a second outlet port 23 c communicating with the distribution line 45 .

[0080] The inlet port 23 a may receive the refrigerant exhausted from the second passage 26 b of the refrigerant heat exchanger 26 .

[0081] The opening degree of the first outlet port 23b can be adjusted based on the pressure (discharge pressure of the compressor 11) and temperature (discharge temperature of the compressor 11) of the high-pressure refrigerant sensed by the high-pressure refrigerant sensor 18. When the opening degree of the first outlet port 23b is adjusted, the flow rate of the refrigerant entering the cooling-side expansion valve 14 can be adjusted. In addition, the first outlet port 23b can be fully opened or fully closed, so that the first outlet port 23b can be used as a stop valve located on the upstream side of the cooling-side expansion valve 14.

[0082] When the first outlet port 23b is completely closed, the refrigerant may be directed only to the battery cooler 25, and not to the cooling-side expansion valve 14 and the evaporator 15. That is, when the first outlet port 23b is completely closed, the cooling operation of the HVAC system may not be performed, and only the battery cooler 25 may be cooled or the heating operation of the HVAC system may be performed. When the first outlet port 23b is completely opened, the refrigerant may be directed to the cooling-side expansion valve 14 and the evaporator 15. That is, when the first outlet port 23b is opened to a predetermined degree, heating and dehumidification of the passenger compartment may be performed.

[0083] The inlet of the distribution line 45 may be directly connected to the second outlet port 23c. The opening degree of the second outlet port 23c may be adjusted according to the state (pressure, temperature, etc.) of the refrigerant, the temperature of the battery, and the like.

[0084] The opening degree of the second outlet port 23c can be adjusted based on the pressure (suction pressure of the compressor 11) and temperature (suction temperature of the compressor 11) of the low-pressure refrigerant sensed by the low-pressure refrigerant sensor 17. That is, the opening degree of the second outlet port 23c can be adjusted to correspond to the suction pressure and suction temperature of the compressor 11, so that the refrigerant discharged from the second outlet port 23c can expand, and the pressure and temperature of the refrigerant discharged from the second outlet port 23c can be reduced to be substantially equal to the pressure and temperature of the low-pressure refrigerant discharged from the first channel 24a of the water-cooled heat exchanger 24. Figures 3 to 5 When the low-pressure refrigerant discharged from the first channel 24a of the water-cooled heat exchanger 24 and the refrigerant discharged from the second outlet port 23c of the third control valve 23 converge at the junction 39a located on the upstream side of the first channel 26a of the refrigerant heat exchanger 26, the opening of the second outlet port 23c can be adjusted to correspond to the pressure and temperature of the low-pressure refrigerant sensed by the low-pressure refrigerant sensor 17, so that the pressure and temperature of the refrigerant discharged from the second outlet port 23c can be similar to or equal to the pressure and temperature of the low-pressure refrigerant discharged from the first channel 24a of the water-cooled heat exchanger 24.

[0085] In addition, when the HVAC system is operated in a battery cooling mode for cooling the battery, the opening of the second outlet port 23c may be adjusted based on the temperature of the battery so that the second outlet port 23c may be used as a cooler-side expansion valve that expands the refrigerant passing through the battery cooler 25. When the opening of the second outlet port 23c is adjusted, the refrigerant may expand at the second outlet port 23c, and the expanded refrigerant may be directed to the battery cooler 25. When the opening of the second outlet port 23c is adjusted, the refrigerant discharged from the second outlet port 23c may expand, and thus the pressure and temperature of the refrigerant discharged from the second outlet port 23c may decrease. In addition, the second outlet port 23c may be fully opened or fully closed. When the second outlet port 23c is fully opened, the refrigerant may be directed to the battery cooler 25 without expanding.

[0086] Reference Figure 1 , the inlet of the first channel 26a of the refrigerant heat exchanger 26 may be located on the downstream side of the third bypass line 43 and the downstream side of the evaporator 15, and the outlet of the first channel 26a of the refrigerant heat exchanger 26 may be located on the upstream side of the compressor 11. The inlet of the second channel 26b of the refrigerant heat exchanger 26 may be located on the downstream side of the external heat exchanger 13 and the downstream side of the first bypass line 41, and the outlet of the second channel 26b of the refrigerant heat exchanger 26 may be located on the upstream side of the cooling-side expansion valve 14.

[0087] Reference Figure 1 The refrigerant circulation passage 30 may include a first pipe 31 extending from the outlet of the compressor 11 to the internal condenser 12, a second pipe 32 extending from the internal condenser 12 to the first control valve 21, a third pipe 33 extending from the first outlet port 21b of the first control valve 21 to the inlet port 22a of the second control valve 22, a fourth pipe 34 extending from the first outlet port 22b of the second control valve 22 to the inlet of the external heat exchanger 13, a fifth pipe 35 connected to the outlet of the external heat exchanger 13, a sixth pipe 36 extending from the fifth pipe 35 to the inlet of the cooling side expansion valve 14, a seventh pipe 37 extending from the outlet of the cooling side expansion valve 14 to the inlet of the evaporator 15, an eighth pipe 38 connected to the outlet of the evaporator 15, and a ninth pipe 39 extending from the eighth pipe 38 to the inlet of the compressor 11.

[0088] The first bypass line 41 and the fifth line 35 may be connected to the junction point 36a of the sixth line 36, and the first bypass line 41 may extend from the second outlet port 21c of the first control valve 21 to the junction point 36a of the sixth line 36 located on the upstream side of the refrigerant heat exchanger 26. The junction point 36a of the sixth line 36 may be located on the upstream side of the second passage 26b of the refrigerant heat exchanger 26. Therefore, the first bypass line 41 may be fluidically connected to the second passage 26b of the refrigerant heat exchanger 26 through the sixth line 36.

[0089] The second bypass line 42 may be connected to the fourth line 34, and the second bypass line 42 may extend from the third outlet port 21d of the first control valve 21 to a junction point 34a of the fourth line 34 located on the downstream side of the first outlet port 22b of the second control valve 22. The junction point 34a of the fourth line 34 may be located between the first outlet port 22b of the second control valve 22 and the inlet of the external heat exchanger 13. Therefore, the second bypass line 42 may be fluidically connected to the external heat exchanger 13 through the fourth line 34.

[0090] The third bypass line 43 and the eighth line 38 may be connected to the junction 39a of the ninth line 39, and the third bypass line 43 may extend from the second outlet port 22c of the second control valve 22 to the junction 39a of the ninth line 39. The junction 39a of the ninth line 39 may be located at an upstream side of the first passage 26a of the refrigerant heat exchanger 26. Therefore, the third bypass line 43 may be fluidically connected to the first passage 26a of the refrigerant heat exchanger 26 through the ninth line 39.

[0091] The distribution line 45 may extend from the second outlet port 23c of the third control valve 23 to the junction point 38a of the eighth line 38. The junction point 38a of the eighth line 38 may be located between the junction point 39a of the ninth line 39 and the outlet of the evaporator 15.

[0092] The HVAC system may further include a check valve 28 disposed between the outlet of the exterior heat exchanger 13 and the second passage 26b of the refrigerant heat exchanger 26. The check valve 28 may be located on the upstream side of the junction 36a of the sixth line 36. The check valve 28 may be configured to allow the refrigerant to flow from the exterior heat exchanger 13 to the second passage 26b of the refrigerant heat exchanger 26, and to prevent the refrigerant from flowing from the second passage 26b of the refrigerant heat exchanger 26 to the exterior heat exchanger 13.

[0093] The controller 100 may be configured to control the respective operations of the compressor 11 , the first control valve 21 , the second control valve 22 , and the third control valve 23 , and thus the overall operation of the HVAC system may be controlled by the controller 100 .

[0094] Figure 22 shows the flow of refrigerant when the HVAC system according to an exemplary embodiment of the present invention is operated in a heating mode. Figure 2 , when the compressor 11 is operated at a predetermined RPM, the compressor 11 may compress the refrigerant, and the refrigerant discharged from the outlet of the compressor 11 may be in a high temperature and high pressure state. The RPM of the compressor 11 may be controlled based on the pressure (discharge pressure of the compressor 11) and temperature (discharge temperature of the compressor 11) of the high pressure refrigerant sensed by the high pressure refrigerant sensor 18, the duty cycle (or RPM) of the blower, the vehicle speed, etc.

[0095] The refrigerant compressed by the compressor 11 may be guided to the interior condenser 12 , and the interior condenser 12 may be cooled by the air passing through the HVAC case 60 , so that the refrigerant passing through the interior condenser 12 may be condensed by the air, and the air may be heated.

[0096] The opening degree of the first outlet port 21b of the first control valve 21 may be adjusted based on the pressure (discharge pressure of the compressor 11) and temperature (discharge temperature of the compressor 11) of the high-pressure refrigerant sensed by the high-pressure refrigerant sensor 18, so that the refrigerant discharged from the first outlet port 21b may expand. The refrigerant discharged from the first outlet port 21b of the first control valve 21 may be guided to the first passage 24a of the water-cooled heat exchanger 24, and the refrigerant passing through the first passage 24a of the water-cooled heat exchanger 24 may absorb heat from the coolant passing through the second passage 24b of the water-cooled heat exchanger 24, and thus the refrigerant may evaporate in the water-cooled heat exchanger 24.

[0097] The first outlet port 22 b of the second control valve 22 can be closed, and the second outlet port 22 c of the second control valve 22 can be opened, so that the refrigerant discharged from the first channel 24 a of the water-cooled heat exchanger 24 can be guided to the first channel 26 a of the refrigerant heat exchanger 26 through the third bypass line 43.

[0098] When the ambient temperature is relatively low and the temperature of the coolant is relatively low, the evaporation of the refrigerant in the water-cooled heat exchanger 24 may be insufficient. In order to improve the heating efficiency of the HVAC system, an additional heat source is required to fully evaporate the refrigerant. Therefore, the HVAC system needs to operate in a heating enhancement mode or a heating enhancement mode.

[0099] Figure 3 2 shows the flow of refrigerant when the HVAC system according to an exemplary embodiment of the present invention is operated in a heating enhancement mode or a heating intensification mode. Figure 3, when the compressor 11 is operated at a predetermined RPM, the compressor 11 may compress the refrigerant, and the refrigerant discharged from the outlet of the compressor 11 may be in a high temperature and high pressure state. The RPM of the compressor 11 may be controlled based on the pressure (discharge pressure of the compressor 11) and temperature (discharge temperature of the compressor 11) of the high pressure refrigerant sensed by the high pressure refrigerant sensor 18, the duty cycle (or RPM) of the blower, the vehicle speed, etc.

[0100] The refrigerant compressed by the compressor 11 may be directed to the interior condenser 12, and the interior condenser 12 may be cooled by the air passing through the HVAC housing 60, so that the refrigerant passing through the interior condenser 12 may be condensed by the air, and the air may be heated. The temperature and pressure of the refrigerant discharged from the interior condenser 12 may be lower than the temperature and pressure of the refrigerant discharged from the compressor 11, but the temperature and pressure of the refrigerant discharged from the interior condenser 12 are still high.

[0101] The opening degree of the first outlet port 21b of the first control valve 21 can be adjusted based on the discharge pressure and discharge temperature of the compressor 11, and the second outlet port 21c of the first control valve 21 can be opened. Therefore, the refrigerant discharged from the interior condenser 12 can be distributed to the water-cooled heat exchanger 24 and the refrigerant heat exchanger 26 through the first outlet port 21b and the second outlet port 21c of the first control valve 21.

[0102] The opening degree of the first outlet port 21b of the first control valve 21 can be adjusted based on the pressure (discharge pressure of the compressor 11) and temperature (discharge temperature of the compressor 11) of the high-pressure refrigerant sensed by the high-pressure refrigerant sensor 18, so that the refrigerant discharged from the first outlet port 21b can expand. Compared with the pressure and temperature of the refrigerant flowing into the inlet port 21a, the pressure and temperature of the refrigerant discharged from the first outlet port 21b can be relatively reduced by the expansion of the refrigerant. The refrigerant discharged from the first outlet port 21b can pass through the first channel 24a of the water-cooled heat exchanger 24, and the coolant of the coolant system 50 can pass through the second channel 24b of the water-cooled heat exchanger 24. The refrigerant passing through the first channel 24a of the water-cooled heat exchanger 24 can absorb heat from the coolant passing through the second channel 24b of the water-cooled heat exchanger 24, so that the refrigerant can be evaporated once through the water-cooled heat exchanger 24.

[0103] The first outlet port 22 b of the second control valve 22 can be closed, and the second outlet port 22 c of the second control valve 22 can be opened, so that the refrigerant discharged from the first channel 24 a of the water-cooled heat exchanger 24 can be guided to the first channel 26 a of the refrigerant heat exchanger 26 through the third bypass line 43.

[0104] The second outlet port 21c of the first control valve 21 may be opened so that a portion of the refrigerant discharged from the interior condenser 12 may be guided to the second passage 26b of the refrigerant heat exchanger 26 through the second outlet port 21c of the first control valve 21. Since the refrigerant discharged from the second outlet port 21c of the first control valve 21 does not expand, the pressure and temperature of the refrigerant discharged from the second outlet port 21c may be maintained the same as the pressure and temperature of the refrigerant flowing into the inlet port 21a. Therefore, the pressure and temperature of the refrigerant discharged from the second outlet port 21c may be higher than the pressure and temperature of the refrigerant discharged from the first outlet port 21b. The refrigerant discharged from the second outlet port 21c may be guided to the second passage 26b of the refrigerant heat exchanger 26 through the first bypass line 41 and the sixth line 36.

[0105] Since the temperature and pressure of the refrigerant passing through the second passage 26b of the refrigerant heat exchanger 26 are higher than the temperature and pressure of the refrigerant passing through the first passage 26a of the refrigerant heat exchanger 26, the refrigerant passing through the first passage 26a may absorb heat from the refrigerant passing through the second passage 26b, so that the refrigerant passing through the first passage 26a may be secondary evaporated, and at the same time, the refrigerant passing through the second passage 26b may be secondary condensed. The refrigerant discharged from the first passage 26a of the refrigerant heat exchanger 26 may be guided to the compressor 11 after passing through the accumulator 16, and the refrigerant discharged from the second passage 26b of the refrigerant heat exchanger 26 may be guided to the first passage 26a of the refrigerant heat exchanger 26 through the third control valve 23 and the distribution line 45.

[0106] The first outlet port 23b of the third control valve 23 can be closed, and the second outlet port 23c of the third control valve 23 can be opened to a predetermined extent, so that the refrigerant discharged from the second channel 26b of the refrigerant heat exchanger 26 can be guided to the first channel 26a of the refrigerant heat exchanger 26 through the second outlet port 23c of the third control valve 23 and the distribution line 45.

[0107] The opening degree of the second outlet port 23c of the third control valve 23 can be adjusted to correspond to the pressure (suction pressure of the compressor 11) and temperature (suction temperature of the compressor 11) of the low-pressure refrigerant sensed by the low-pressure refrigerant sensor 17, so that the refrigerant discharged from the second outlet port 23c of the third control valve 23 can expand, and the pressure and temperature of the refrigerant discharged from the second outlet port 23c can be reduced to basically equal to the pressure and temperature of the low-pressure refrigerant discharged from the first channel 24a of the water-cooled heat exchanger 24. When the low-pressure refrigerant discharged from the first passage 24a of the water-cooled heat exchanger 24 merges with the refrigerant discharged from the second outlet port 23c of the third control valve 23 at the junction 39a located on the upstream side of the first passage 26a of the refrigerant heat exchanger 26, the opening degree of the second outlet port 23c may be adjusted to correspond to the pressure and temperature of the low-pressure refrigerant sensed by the low-pressure refrigerant sensor 17, so that the pressure and temperature of the refrigerant discharged from the second outlet port 23c may be similar to or equal to the pressure and temperature of the low-pressure refrigerant discharged from the first passage 24a of the water-cooled heat exchanger 24. The refrigerant discharged from the second outlet port 23c of the third control valve 23 may pass through the battery cooler 25, merge with the refrigerant discharged from the first passage 24a of the water-cooled heat exchanger 24 at the junction 39a, and then be guided to the compressor 11 through the first passage 26a of the refrigerant heat exchanger 26.

[0108] When the HVAC system is operated in a heating mode under the condition that the ambient temperature is relatively low (e.g., -20°C to -5°C), the temperature of the coolant circulating in the coolant circulation passage 51 of the coolant system 50 is relatively low, and thus the refrigerant passing through the first passage 24a of the water-cooled heat exchanger 24 may not be able to sufficiently absorb heat from the second passage 24b of the water-cooled heat exchanger 24. Therefore, the refrigerant may not be sufficiently evaporated in the water-cooled heat exchanger 24. That is, under the condition that the ambient temperature is relatively low, the coolant of the coolant system 50 may not provide sufficient heat for the evaporation of the refrigerant passing through the water-cooled heat exchanger 24. In order to solve this problem, the HVAC system according to the exemplary embodiment of the present invention may allow the refrigerant heat exchanger to additionally provide heat for the evaporation of the refrigerant under the condition that the ambient temperature is relatively low. Therefore, the refrigerant may be evaporated in two stages through the water-cooled heat exchanger 24 and the refrigerant heat exchanger 26, whereby the refrigerant may be sufficiently evaporated. As described above, the refrigerant may be evaporated once through the water-cooled heat exchanger 24, and evaporated twice through the refrigerant heat exchanger 26. Therefore, as the refrigerant is fully evaporated, the suction pressure of the compressor can be prevented from dropping below a predetermined threshold pressure, and the compressor can be operated at a predetermined RPM, so that the efficiency of the compressor can be improved. Since the coefficient of performance (COP) of the HVAC system can be improved by using the refrigerant, the operation of the electric heater can be minimized. Therefore, the electrical efficiency of the electric vehicle can be improved.

[0109] When the HVAC system operates in a heating and dehumidification mode when the ambient temperature is relatively low (eg, −20° C. to −5° C.), the refrigerant may pass through the cooling-side expansion valve 14 and the evaporator 15 , and the air passing through the evaporator 15 may be dehumidified.

[0110] Figure 4 2 shows the flow of refrigerant when the HVAC system according to an exemplary embodiment of the present invention is operated in heating and dehumidification modes. Figure 4 , when the compressor 11 is operated at a predetermined RPM, the compressor 11 may compress the refrigerant, and the refrigerant discharged from the outlet of the compressor 11 may be in a high temperature and high pressure state. The RPM of the compressor 11 may be controlled based on the pressure (discharge pressure of the compressor 11) and temperature (discharge temperature of the compressor 11) of the high pressure refrigerant sensed by the high pressure refrigerant sensor 18, the duty cycle (or RPM) of the blower, the vehicle speed, etc.

[0111] The refrigerant compressed by the compressor 11 may be directed to the interior condenser 12, and the interior condenser 12 may be cooled by the air passing through the HVAC housing 60, so that the refrigerant passing through the interior condenser 12 may be condensed by the air, and the air may be heated. The temperature and pressure of the refrigerant discharged from the interior condenser 12 may be lower than the temperature and pressure of the refrigerant discharged from the compressor 11, but the temperature and pressure of the refrigerant discharged from the interior condenser 12 are still high.

[0112] The opening degree of the first outlet port 21b of the first control valve 21 can be adjusted based on the discharge pressure and discharge temperature of the compressor 11, and the second outlet port 21c of the first control valve 21 can be opened. Therefore, the refrigerant discharged from the interior condenser 12 can be distributed to the water-cooled heat exchanger 24 and the refrigerant heat exchanger 26 through the first outlet port 21b and the second outlet port 21c of the first control valve 21.

[0113] The opening degree of the first outlet port 21b of the first control valve 21 can be adjusted based on the pressure (discharge pressure of the compressor 11) and temperature (discharge temperature of the compressor 11) of the high-pressure refrigerant sensed by the high-pressure refrigerant sensor 18, so that the refrigerant discharged from the first outlet port 21b can expand. Compared with the pressure and temperature of the refrigerant flowing into the inlet port 21a, the pressure and temperature of the refrigerant discharged from the first outlet port 21b can be relatively reduced by the expansion of the refrigerant. The refrigerant discharged from the first outlet port 21b can pass through the first channel 24a of the water-cooled heat exchanger 24, and the coolant of the coolant system 50 can pass through the second channel 24b of the water-cooled heat exchanger 24. The refrigerant passing through the first channel 24a of the water-cooled heat exchanger 24 can absorb heat from the coolant passing through the second channel 24b of the water-cooled heat exchanger 24, so that the refrigerant can be evaporated once through the water-cooled heat exchanger 24.

[0114] The first outlet port 22 b of the second control valve 22 can be closed, and the second outlet port 22 c of the second control valve 22 can be opened, so that the refrigerant discharged from the first channel 24 a of the water-cooled heat exchanger 24 can be guided to the first channel 26 a of the refrigerant heat exchanger 26 through the third bypass line 43.

[0115] The second outlet port 21c of the first control valve 21 may be opened so that a portion of the refrigerant discharged from the interior condenser 12 may be guided to the second passage 26b of the refrigerant heat exchanger 26 through the second outlet port 21c of the first control valve 21. Since the refrigerant discharged from the second outlet port 21c of the first control valve 21 does not expand, the pressure and temperature of the refrigerant discharged from the second outlet port 21c may be maintained the same as the pressure and temperature of the refrigerant flowing into the inlet port 21a. Therefore, the temperature and pressure of the refrigerant discharged from the second outlet port 21c may be higher than the temperature and pressure of the refrigerant discharged from the first outlet port 21b. The refrigerant discharged from the second outlet port 21c may be guided to the second passage 26b of the refrigerant heat exchanger 26 through the first bypass line 41 and the sixth line 36.

[0116] Since the temperature and pressure of the refrigerant passing through the second passage 26b of the refrigerant heat exchanger 26 are higher than the temperature and pressure of the refrigerant passing through the first passage 26a of the refrigerant heat exchanger 26, the refrigerant passing through the first passage 26a can absorb heat from the refrigerant passing through the second passage 26b, so that the refrigerant passing through the first passage 26a can be evaporated twice, and at the same time, the refrigerant passing through the second passage 26b can be condensed twice. That is, the refrigerant evaporated once by the water-cooled heat exchanger 24 can be evaporated twice by the refrigerant heat exchanger 26, so that the evaporation of the refrigerant can be fully performed, and the refrigerant condensed once by the internal condenser 12 can be condensed twice by the refrigerant heat exchanger 26, so that the condensation of the refrigerant can be fully performed.

[0117] The refrigerant discharged from the first passage 26a of the refrigerant heat exchanger 26 may be guided to the compressor 11 after passing through the accumulator 16. The second outlet port 23c of the third control valve 23 may be closed, and the first outlet port 23b of the third control valve 23 may be opened to a predetermined extent, so that the refrigerant discharged from the second passage 26b of the refrigerant heat exchanger 26 may be guided to the cooling-side expansion valve 14 through the first outlet port 23b of the third control valve 23.

[0118] The opening degree of the first outlet port 23b of the third control valve 23 can be adjusted based on the pressure (discharge pressure of the compressor 11) and temperature (discharge temperature of the compressor 11) of the high-pressure refrigerant sensed by the high-pressure refrigerant sensor 18, so that the refrigerant discharged from the second passage 26b of the refrigerant heat exchanger 26 can be expanded once at the first outlet port 23b of the third control valve 23. The refrigerant discharged from the first outlet port 23b can be guided to the cooling-side expansion valve 14, and the refrigerant can be expanded twice at the cooling-side expansion valve 14. The secondarily expanded refrigerant can be evaporated in the evaporator 15, and the air passing through the outer surface of the evaporator 15 can be cooled and dehumidified. The refrigerant discharged from the evaporator 15 and the refrigerant discharged from the first passage 24a of the water-cooled heat exchanger 24 can be merged at the junction 39a, and then guided to the compressor 11 through the first passage 26a of the refrigerant heat exchanger 26.

[0119] When the interior temperature of the passenger compartment reaches the target temperature, the duty cycle (or RPM) of the blower may be relatively reduced, so that the flow rate of air blown into the passenger compartment is relatively reduced. Since the flow rate of the blown air is relatively reduced, the interior condenser of the HVAC system may not be able to sufficiently release heat to the air, and thus the condensation of the refrigerant may be relatively reduced. Therefore, the HVAC system needs to be operated in a dehumidification enhancement mode or a dehumidification enhanced mode.

[0120] Figure 52 shows the flow of refrigerant when the HVAC system according to an exemplary embodiment of the present invention is operated in a heating and dehumidification enhancement mode or a heating and dehumidification enhanced mode. Figure 5 , when the compressor 11 is operated at a predetermined RPM, the compressor 11 may compress the refrigerant, and the refrigerant discharged from the outlet of the compressor 11 may be in a high temperature and high pressure state. The RPM of the compressor 11 may be controlled based on the pressure (discharge pressure of the compressor 11) and temperature (discharge temperature of the compressor 11) of the high pressure refrigerant sensed by the high pressure refrigerant sensor 18, the duty cycle (or RPM) of the blower, the vehicle speed, etc.

[0121] The refrigerant compressed by the compressor 11 may be guided to the interior condenser 12, and the interior condenser 12 may be cooled by the air passing through the HVAC housing 60, so that the refrigerant passing through the interior condenser 12 may be condensed once by the air, and the air may be heated. The temperature and pressure of the refrigerant discharged from the interior condenser 12 may be lower than the temperature and pressure of the refrigerant discharged from the compressor 11, but the temperature and pressure of the refrigerant discharged from the interior condenser 12 are still high.

[0122] The opening degree of the first outlet port 21b of the first control valve 21 may be adjusted based on the discharge pressure and discharge temperature of the compressor 11, the second outlet port 21c of the first control valve 21 may be closed, and the third outlet port 21d of the first control valve 21 may be opened. Therefore, the refrigerant discharged from the interior condenser 12 may be distributed to the water-cooled heat exchanger 24 and the exterior heat exchanger 13 through the first outlet port 21b and the third outlet port 21d of the first control valve 21.

[0123] The opening degree of the first outlet port 21b of the first control valve 21 can be adjusted based on the pressure (suction pressure of the compressor 11) and temperature (suction temperature of the compressor 11) of the high-pressure refrigerant sensed by the high-pressure refrigerant sensor 18, so that the refrigerant discharged from the first outlet port 21b can expand. Compared with the pressure and temperature of the refrigerant flowing into the inlet port 21a, the pressure and temperature of the refrigerant discharged from the first outlet port 21b can be relatively reduced by the expansion of the refrigerant. The refrigerant discharged from the first outlet port 21b can pass through the first channel 24a of the water-cooled heat exchanger 24, and the coolant of the coolant system 50 can pass through the second channel 24b of the water-cooled heat exchanger 24. The refrigerant passing through the first channel 24a of the water-cooled heat exchanger 24 can absorb heat from the coolant passing through the second channel 24b of the water-cooled heat exchanger 24, so that the refrigerant can be evaporated once through the water-cooled heat exchanger 24.

[0124] The first outlet port 22 b of the second control valve 22 can be closed, and the second outlet port 22 c of the second control valve 22 can be opened, so that the refrigerant discharged from the first channel 24 a of the water-cooled heat exchanger 24 can be guided to the first channel 26 a of the refrigerant heat exchanger 26 through the third bypass line 43.

[0125] The third outlet port 21d of the first control valve 21 may be opened so that a portion of the refrigerant discharged from the interior condenser 12 may be guided to the exterior heat exchanger 13 through the third outlet port 21d of the first control valve 21 and the second bypass line 42. The refrigerant passing through the interior refrigerant passage of the exterior heat exchanger 13 may be secondary condensed by the ambient air passing through the outer surface of the evaporator 15.

[0126] The refrigerant discharged from the external heat exchanger 13 may be guided to the second channel 26b of the refrigerant heat exchanger 26 through the fifth pipe 35 and the sixth pipe 36. Since the temperature and pressure of the refrigerant secondarily condensed through the external heat exchanger 13 are higher than the temperature and pressure of the refrigerant evaporated through the water-cooled heat exchanger 24, the refrigerant passing through the second channel 26b of the refrigerant heat exchanger 26 may release heat to the refrigerant passing through the first channel 26a of the refrigerant heat exchanger 26, so that the refrigerant secondarily condensed through the external heat exchanger 13 may then be condensed through the refrigerant heat exchanger 26. That is, the refrigerant may be condensed once through the internal condenser 12, secondarily condensed through the external heat exchanger 13, and then condensed through the refrigerant heat exchanger 26, and thus the subcooling of the refrigerant may be sufficiently performed. Since the subcooling of the refrigerant is sufficiently performed, the heating and dehumidification of the passenger compartment may be stably achieved using the refrigerant. Therefore, the operation of the electric heater 62 may be minimized, and thus the electrical efficiency of the electric vehicle may be improved.

[0127] The second outlet port 23c of the third control valve 23 may be closed, and the opening degree of the first outlet port 23b of the third control valve 23 may be adjusted based on the pressure (discharge pressure of the compressor 11) and temperature (discharge temperature of the compressor 11) of the high-pressure refrigerant sensed by the high-pressure refrigerant sensor 18, so that the refrigerant discharged from the first outlet port 23b may be expanded once. The refrigerant discharged from the first outlet port 23b may be guided to the cooling side expansion valve 14, and the refrigerant may be expanded twice at the cooling side expansion valve 14. The twice-expanded refrigerant may be guided to the evaporator 15, so that the refrigerant may evaporate in the evaporator 15, and the air passing through the outer surface of the evaporator 15 may be cooled and dehumidified. The refrigerant discharged from the evaporator 15 and the refrigerant discharged from the first passage 24a of the water-cooled heat exchanger 24 may be combined at the junction 39a, and then guided to the compressor 11 through the first passage 26a of the refrigerant heat exchanger 26.

[0128] As described above, according to an exemplary embodiment of the present invention, when the HVAC system is operated in the heating enhancement mode, the refrigerant can be evaporated twice through the water-cooled heat exchanger and the refrigerant heat exchanger. Since the evaporation of the refrigerant is stably performed, the suction pressure of the compressor can be prevented from dropping below the threshold pressure, and the compressor can be operated at a predetermined RPM, so the efficiency of the compressor can be improved. Since the coefficient of performance (COP) of the HVAC system can be improved by using the refrigerant, the operation of the electric heater can be minimized, and thus the electrical efficiency of the electric vehicle can be improved.

[0129] According to an exemplary embodiment of the present invention, when the HVAC system is operated in the heating and dehumidification enhancement mode, the refrigerant can be condensed three times through the internal condenser, the external heat exchanger, and the refrigerant heat exchanger. Since the condensation of the refrigerant is stably performed, the heating and dehumidification of the passenger compartment can be smoothly performed. Therefore, the operation of the electric heater can be minimized, and thus the electrical efficiency of the electric vehicle can be improved.

[0130] Although the present invention has been described above with reference to exemplary embodiments and the accompanying drawings, the present invention is not limited thereto but may be variously modified and changed by those skilled in the art without departing from the spirit and scope of the present invention as claimed in the appended claims.

Claims

1. A vehicle HVAC system, comprising: compressor; an internal condenser located on the downstream side of the compressor; a water-cooled heat exchanger located on a downstream side of the internal condenser, the water-cooled heat exchanger being configured to transfer heat between the refrigerant and a coolant circulating in a coolant system; an external heat exchanger located on a downstream side of the water-cooled heat exchanger, the external heat exchanger being configured to transfer heat between the refrigerant and ambient air; a refrigerant heat exchanger configured to transfer heat between refrigerant exhausted from the water-cooled heat exchanger and refrigerant exhausted from the interior condenser; as well as A first control valve is located between the water-cooled heat exchanger and the interior condenser, the first control valve being configured to allow refrigerant exhausted from the interior condenser to be directed to at least one of the water-cooled heat exchanger, the refrigerant heat exchanger, and the exterior heat exchanger.

2. The vehicle HVAC system according to claim 1, wherein: The refrigerant heat exchanger comprises: a first passage through which the refrigerant discharged from the water-cooled heat exchanger passes; and A second passage through which refrigerant exhausted from at least one of the interior condenser and the exterior heat exchanger passes.

3. The vehicle HVAC system of claim 2, further comprising a first bypass line configured to allow at least a portion of the refrigerant exhausted from the interior condenser to be directed from an upstream point of the water-cooled heat exchanger to a downstream point of the exterior heat exchanger, wherein The first bypass line is fluidly connected to the second passage of the refrigerant heat exchanger.

4. The vehicle HVAC system of claim 3, further comprising a second bypass line configured to allow at least a portion of the refrigerant exhausted from the interior condenser to be directed from a point upstream of the water-cooled heat exchanger to a point upstream of the exterior heat exchanger, wherein The second bypass line is fluidly connected to an inlet of the external heat exchanger.

5. The vehicle HVAC system according to claim 4, wherein: The first control valve comprises: an inlet port in communication with the internal condenser; a first outlet port in communication with the water-cooled heat exchanger; a second outlet port in communication with the first bypass line; and A third outlet port is in communication with the second bypass line.

6. The vehicle HVAC system according to claim 5, wherein: The opening degree of the first outlet port is adjusted based on the discharge pressure and discharge temperature of the compressor.

7. The vehicle HVAC system of claim 2, further comprising a third bypass line configured to allow at least a portion of the refrigerant exhausted from the water-cooled heat exchanger to be directed from an upstream point of the external heat exchanger to an upstream point of the compressor, wherein The third bypass line is fluidly connected to an inlet of the first passage of the refrigerant heat exchanger. 8 . The vehicle HVAC system of claim 7 , further comprising a second control valve configured to allow refrigerant exhausted from the water-cooled heat exchanger to be directed to at least one of the external heat exchanger and the first passage of the refrigerant heat exchanger.

9. The vehicle HVAC system of claim 8, wherein: The second control valve comprises: an inlet port in communication with the water-cooled heat exchanger; a first outlet port in communication with the external heat exchanger; and A second outlet port is in communication with the third bypass line.

10. The vehicle HVAC system of claim 2, further comprising a check valve between the external heat exchanger and the second passage of the refrigerant heat exchanger, wherein: The check valve is configured to allow the refrigerant to flow from the external heat exchanger to the second passage of the refrigerant heat exchanger and prevent the refrigerant from flowing back from the second passage of the refrigerant heat exchanger to the external heat exchanger.

11. The vehicle HVAC system of claim 2, further comprising: a cooling-side expansion valve located on a downstream side of the second passage of the refrigerant heat exchanger; an evaporator located downstream of the cooling-side expansion valve; a distribution line configured to allow at least a portion of the refrigerant discharged from the second passage of the refrigerant heat exchanger to be directed from an upstream point of the cooling-side expansion valve to a downstream point of the evaporator; as well as A battery cooler is fluidly connected to the distribution line and thermally connected to the battery cooling system. 12 . The vehicle HVAC system of claim 11 , further comprising a third control valve configured to allow refrigerant exhausted from the second passage of the refrigerant heat exchanger to be directed to at least one of the cooling-side expansion valve and the battery cooler.

13. The vehicle HVAC system of claim 12, wherein: The third control valve comprises: an inlet port in communication with the second passage of the refrigerant heat exchanger; a first outlet port in communication with the cooling-side expansion valve; and A second outlet port is in communication with the dispensing line.

14. The vehicle HVAC system of claim 13, wherein: The opening degree of the first outlet port is adjusted based on a discharge pressure of the compressor.

15. The vehicle HVAC system of claim 13, wherein: The opening degree of the second outlet port is adjusted based on the suction pressure of the compressor.

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