VEHICLE CABIN AND RECHARGEABLE ENERGY STORAGE SYSTEM THERMAL MANAGEMENT SYSTEM

A heating, ventilation and air conditioning (HVAC) system for a vehicle having a rechargeable energy storage system includes a refrigerant circuit having a flow of refrigerant circulated therethrough. The refrigerant circuit includes a compressor, an internal condenser, and a chiller heat exchanger. A coolant circuit is fluidly connected to the refrigerant circuit and has a flow of coolant circulated therethrough. The coolant circuit includes the internal condenser, a heater core, and a rechargeable energy storage system (RESS). The refrigerant circuit and the coolant circuit exchange thermal energy at the internal condenser. When operated in an HVAC operating mode, the HVAC system is configured to heat one or more of the heater core and the RESS with thermal energy generated at the compressor.

The subject disclosure relates to electric vehicles, and more precisely to heating of a cabin and a rechargeable energy storage system (RESS) of an electric vehicle.

A typical RESS, also known by the term a “Battery Pack” or other similar nomenclature has an optimal performance within a narrow temperature range. When operating conditions fall outside of this range at an upper end, the RESS is cooled by circulating a flow of coolant therethrough. When, on the other hand, the operating temperature is low, it is desired to heat the RESS to maintain performance. This heating is typically achieved via a separate cooling heater connected to the system. This separate cooling heater adds complexity to the system and increases energy usage of the system to provide heating of the RESS.

SUMMARY

In one embodiment, a heating, ventilation and air conditioning (HVAC) system for a vehicle having a rechargeable energy storage system includes a refrigerant circuit having a flow of refrigerant circulated therethrough. The refrigerant circuit includes a compressor, an internal condenser, and a chiller heat exchanger. A coolant circuit is fluidly connected to the refrigerant circuit and has a flow of coolant circulated therethrough. The coolant circuit includes the internal condenser, a heater core, and a rechargeable energy storage system (RESS). The refrigerant circuit and the coolant circuit exchange thermal energy at the internal condenser. When operated in an HVAC operating mode, the HVAC system is configured to heat one or more of the heater core and the RESS with thermal energy generated at the compressor.

Additionally or alternatively, in this or other embodiments in the HVAC operating mode, the HVAC system is configured to heat one or more of the heater core and the RESS with only thermal energy generated at the compressor.

Additionally or alternatively, in this or other embodiments the flow of coolant is selectably flowed through the chiller heat exchanger to exchange thermal energy with the flow of coolant at the chiller heat exchanger.

Additionally or alternatively, in this or other embodiments the coolant circuit includes a chiller coolant bypass valve to selectably direct the flow of coolant along a chiller coolant bypass passage or through the chiller heat exchanger.

Additionally or alternatively, in this or other embodiments the HVAC operating mode is engaged when an ambient air temperature is less than −10 degrees Celsius.

Additionally or alternatively, in this or other embodiments a pump urges circulation of the flow of coolant through the coolant circuit.

Additionally or alternatively, in this or other embodiments the pump is located in the coolant circuit fluidly upstream of the internal condenser and the heater core, and fluidly downstream of the RESS.

Additionally or alternatively, in this or other embodiments the refrigerant circuit includes an outside heat exchanger fluidly connected to the internal condenser and the compressor.

Additionally or alternatively, in this or other embodiments when the HVAC system is operated in a heat pump mode, the flow of refrigerant is directed through the outside heat exchanger to absorb thermal energy from ambient air, bypassing the chiller heat exchanger.

Additionally or alternatively, in this or other embodiments an outside heat exchanger expansion valve is operable to selectably direct the flow of refrigerant through the outside heat exchanger.

Additionally or alternatively, in this or other embodiments the heat pump mode is engaged when an ambient air temperature is greater than −10 degrees Celsius.

In another embodiment, a method of heating a rechargeable energy storage system of a vehicle includes circulating a flow of refrigerant through a refrigerant circuit. The refrigerant circuit includes a compressor, an internal condenser, and a chiller heat exchanger. A flow of coolant is circulated through a coolant circuit. The coolant circuit includes the internal condenser, a heater core, and a rechargeable energy storage system (RESS). The flow of refrigerant is heated via operation of the compressor and thermal energy is exchanged between the flow of refrigerant and the flow of coolant at the internal heat condenser. One or more of the heater core and the RESS is heated via the flow of coolant.

Additionally or alternatively, in this or other embodiments in an HVAC operating mode heating one or more of the heater core and the RESS with only thermal energy generated at the compressor.

Additionally or alternatively, in this or other embodiments the HVAC operating mode is engaged when an ambient air temperature is less than −10 degrees Celsius.

Additionally or alternatively, in this or other embodiments the flow of coolant is selectably flowed through the chiller heat exchanger to exchange thermal energy with the flow of coolant at the chiller heat exchanger.

Additionally or alternatively, in this or other embodiments the coolant circuit includes a chiller coolant bypass valve to selectably direct the flow of coolant along a chiller coolant bypass passage or through the chiller heat exchanger.

Additionally or alternatively, in this or other embodiments an outside heat exchanger is located in the refrigerant circuit and is fluidly connected to the internal condenser and the compressor.

Additionally or alternatively, in this or other embodiments when in a heat pump mode, the flow of refrigerant is directed through the outside heat exchanger to absorb thermal energy from ambient air, bypassing the chiller heat exchanger.

Additionally or alternatively, in this or other embodiments the heat pump mode is engaged when an ambient air temperature is greater than −10 degrees Celsius.

DETAILED DESCRIPTION

In accordance with an exemplary embodiment, an illustration of a heating, ventilation, and air conditioning (HVAC) system10for a vehicle is shown inFIG.1. The vehicle includes a rechargeable energy storage system (RESS)12, such as electric rechargeable traction batteries, electric double-layer capacitors or flywheel energy storage, and a heater core14as part of a coolant circuit16, through which a flow of coolant is circulated. The heater core14is utilized for heating of a cabin of the vehicle. The flow of coolant is circulated through the coolant circuit16via a coolant pump18, which in some embodiments is located between the RESS12and the heater core14. An internal condenser20is located along the coolant circuit16, in some embodiments between the coolant pump18and the heater core14, and connects the coolant circuit16to a refrigerant circuit22arranged in parallel with the coolant circuit16.

In the internal condenser20, the flow of coolant of the coolant circuit16exchanges thermal energy with a flow of refrigerant from the refrigerant circuit22. The refrigerant circuit22further includes a compressor24disposed fluidly upstream of the internal condenser20, and three heat exchangers arranged in a fluidly parallel relationship downstream of the internal condenser20. The three heat exchangers include an outside heat exchanger26, an evaporator28and a chiller heat exchanger30. Each heat exchanger has an associated expansion device located fluidly between the internal condenser20and the respective heat exchanger. The expansion devices are, respectively, an outside expansion valve32, an evaporator expansion valve34and a chiller expansion valve36. The chiller heat exchanger30is further connected to the coolant circuit16for thermal energy exchange between the flow of coolant and the flow of refrigerant at the chiller heat exchanger30.

The HVAC system10is configured to operate in several operating modes, depending on the thermal demands of the RESS12and the heater core14, as well as on ambient conditions and operating conditions of the vehicle, as will be discussed in greater detail below. To facilitate switching of operating modes, the HVAC system10includes a plurality of valves to selectably direct the flow of coolant and the flow of refrigerant along selected fluid pathways in the coolant circuit16and the refrigerant circuit22. The coolant circuit16includes a RESS bypass valve38to selectably direct the flow of coolant along a RESS bypass passage40or through the RESS12, a chiller coolant bypass valve42to selectably direct the flow of coolant along a chiller coolant bypass passage44or through the chiller heat exchanger30, an internal condenser bypass valve46to selectably direct the flow of coolant along an internal condenser coolant bypass passage48or through the internal condenser20, and a coolant four-way valve50upstream of the coolant pump18. The other two connections on the coolant four-way valve50are connected to a power electronics coolant loop56, which in some embodiments includes an associated low temperature radiator (not shown). The coolant four-way valve50can be operated in split mode where the coolant flow through the coolant circuit16and the power electronics coolant loop56is separated or in combined mode where the coolant flow through coolant circuit16and the power electronics coolant loop56is mixed. In addition to the aforementioned expansion valves, the refrigerant circuit22includes an outside heat exchanger valve52and an internal condenser refrigerant valve54to selectably direct the flow of refrigerant from the compressor24through the outside heat exchanger26or through the internal condenser20.

A first operating mode of the HVAC system10is illustrated inFIG.2. This first mode is utilized, for example, when the cabin is requesting heating via the heater core14and a target discharge temperature of the heater core14is greater than 50 degrees Celsius. In the first mode, the internal condenser refrigerant valve54is open, the outside heat exchanger valve52is closed, the outside expansion valve32, is closed, the evaporator expansion valve34is closed, and the chiller expansion valve36is opened. This directs the flow of refrigerant along the refrigerant circuit22through the compressor24, the internal condenser20, the chiller expansion valve36, the chiller heat exchanger30and back to the compressor24, bypassing the outside heat exchanger26and the evaporator28. In the coolant circuit16, the internal condenser bypass valve46is set to direct the coolant flow through the internal condenser20, and the chiller coolant bypass valve42is set to direct the flow of coolant through the chiller heat exchanger30, while the RESS bypass valve38is set to direct the flow of coolant along the RESS bypass passage40. Thus, the flow of coolant is directed along the coolant circuit16from the pump46through the internal condenser20, the heater core14and the chiller heat exchanger30. The RESS bypass valve38directs the flow of coolant along the RESS bypass passage40thus bypassing the RESS12before being directed back to the pump18. The cabin is thus heated by the heater core14by the heat of compression from the compressor24, without the introduction of outside ambient air for heat removal from the RESS12.

If, on the other hand, the target discharge temperature of the heater core14not greater than 50 degrees Celsius, the HVAC system10is operated in a second mode where the valves38,42and46are modulated to provide the desired amount of heating to the heater core14, as illustrated inFIG.3. In the second mode, the chiller coolant bypass valve42is selectably or partially opened to modulate flow of coolant through the chiller heat exchanger30and the chiller coolant bypass passage44. Similarly, the RESS bypass valve38is partially or selectably opened to modulate the flow of coolant along the RESS bypass passage40and through the RESS12. The internal condenser bypass valve46is similarly selectably or partially opened to modulate the flow of coolant along the internal condenser coolant bypass passage48or through the internal condenser20. This modulation of the valves38,42and46provides the desired amount of heating to the heater core14.

Referring now toFIG.4, in a third mode the internal condenser bypass valve46is set to direct the coolant flow through the internal condenser20, and the chiller coolant bypass valve42is set to direct the flow of coolant through the chiller heat exchanger30, while the RESS bypass valve38is set to direct the flow of coolant through the RESS12. Thus, the flow of coolant is directed along the coolant circuit16from the pump18through the internal condenser20, the heater core14and the chiller heat exchanger30. The RESS bypass valve38directs the flow of coolant through the RESS12before being directed back to the pump18. The cabin is thus heated by the heater core14, and the RESS12is heated by the heat of compression from the compressor24, without the introduction of outside ambient air for heat removal from the RESS12.

The valve and flow configuration shown inFIG.4may also be utilized to operate the HVAC system10in a fourth mode, where waste heat from the RESS12is utilized to further provide heat to the heater core14for cabin heating. This mode may be utilized when the ambient temperature is very low, for example, less than −10 degrees Celsius and the temperature of the RESS12is relatively high, such as greater than 10 degrees Celsius.

In some embodiments, such as when the ambient temperature is greater than −10 degrees Celsius, the HVAC system10operates as a heat pump, drawing heat from outside air via the outside heat exchanger26. Referring now toFIG.5, when the ambient temperature is greater than −10 degrees Celsius, and the target discharge temperature of the heater core14is greater than 50 degrees Celsius, the HVAC system10operates in a fifth mode. In this fifth mode, the internal condenser refrigerant valve54is opened and the outside heat exchanger refrigerant valve52is closed. The outside heat exchanger expansion valve32is opened, and both the evaporator expansion valve34and the chiller expansion valve36are closed. Thus, in the refrigerant circuit22the refrigerant flows from the compressor24through the internal condenser20and then through the outside heat exchanger26which acts as an evaporator by exchanging thermal energy with outside air. From the outside heat exchanger26, the refrigerant returns to the compressor24. In the coolant circuit16, the coolant valves38,42,46and50are set to direct the flow of coolant from the pump18and through the internal condenser20and then the heater core14. The flow of coolant then bypasses the chiller heat exchanger30and the RESS12as directed by valves38and42. From the RESS bypass passage40, the flow of coolant then returns to the pump18.

In another embodiment, illustrated inFIG.6, the HVAC system10operates in a sixth mode, where the RESS12requires heating. In this mode, in the coolant circuit16, the coolant valves38,42,46and50are set to direct the flow of coolant from the pump18and through the internal condenser20and then the heater core14. The flow of coolant then flows through the chiller heat exchanger30and the RESS12as directed by valves38and42. From the RESS12, the flow of coolant then returns to the pump18.

The HVAC system10described herein utilizes the refrigerant circuit22to heat the cabin via the heater core14and the RESS12by utilizing only compressor24power, and not utilizing a typical coolant heater in cold weather (less than −10 degrees Celsius). This is accomplished by routing the flow of coolant in the coolant circuit16through the internal condenser20and the heater core14. The system10can also be operated to pull heat from ambient when the ambient temperature is higher, thus saving energy usage.