Heat pump and hvac system architecture for electric vehicles

Abstract

An HVAC system of an electric vehicle includes a housing having an inlet for receiving a flow of air therethrough and an air outlet in fluid communication with a passenger compartment of the vehicle. The HVAC system further includes a first heat exchanger disposed in the housing and a second heat exchanger disposed in the housing downstream from the first heat exchanger with respect of a direction of the flow of air through the housing. A primary circuit containing a flow of refrigerant therethrough is in fluid communication with the first heat exchanger. A secondary circuit is in one of fluid communication with and heat exchange communication with the primary circuit and in fluid communication with the second heat exchanger.

What is claimed is: 
     
         1 . An HVAC system of an electric vehicle comprising:
 a housing having an inlet for receiving a flow of air therethrough and an outlet in fluid communication with a passenger compartment of the vehicle;   a first heat exchanger disposed in the housing and configured to receive the flow of air therethrough;   a second heat exchanger disposed in the housing downstream from the first heat exchanger with respect of a direction of the flow of air through the housing, the second heat exchanger configured to receive the flow of air;   a primary circuit containing a refrigerant therein and in fluid communication with the first heat exchanger, the primary circuit including a compressor, a third heat exchanger, at least one expansion valve, and a plurality of valves, each of the valves cooperating with each other to selectively convey the refrigerant through the first heat exchanger in a first direction and a second direction; and   a secondary circuit in one of fluid communication with and heat exchange communication with a portion of the primary circuit intermediate the third heat exchanger and the at least one expansion valve, the secondary circuit in fluid communication with the second heat exchanger.   
     
     
         2 . The HVAC system of  claim 1 , wherein the second heat exchanger is separate from the first heat exchanger. 
     
     
         3 . The HVAC system of  claim 1 , wherein the second heat exchanger is one of integrally formed with the first heat exchanger, coupled to the first heat exchanger, and abutting with the first heat exchanger. 
     
     
         4 . The HVAC system of  claim 1 , wherein the second heat exchanger has a width less than a width of the first heat exchanger. 
     
     
         5 . The HVAC system of  claim 1 , wherein the first heat exchanger is configured to be an evaporator to receive the refrigerant conveyed therethrough in the first direction and a heater core to receive the refrigerant conveyed therethrough in the second direction. 
     
     
         6 . The HVAC system of  claim 1 , wherein the primary circuit includes at least one bypass cooperating with the plurality of valves to convey the refrigerant through the first heat exchanger in the second direction. 
     
     
         7 . The HVAC system of  claim 1 , wherein the primary circuit includes a fourth heat exchanger disposed adjacent and in fluid communication with the third heat exchanger. 
     
     
         8 . The HVAC system of  claim 7 , wherein the secondary circuit is in heat exchange communication with the primary circuit and in fluid communication with the fourth heat exchanger. 
     
     
         9 . The HVAC system of  claim 1 , wherein the secondary circuit contains one of the refrigerant and a coolant. 
     
     
         10 . The HVAC system of  claim 9 , wherein the secondary circuit includes at least one of a valve and a bypass to selectively control a direction of a flow of the one of the refrigerant and the coolant. 
     
     
         11 . The HVAC system of  claim 1 , wherein the secondary circuit is in heat exchange communication with the primary circuit and contains a coolant and a fluid control device for conveying the coolant therethrough. 
     
     
         12 . The HVAC system of  claim 1 , wherein the secondary circuit is in heat exchange communication with a battery of the vehicle. 
     
     
         13 . A method for operating an HVAC system of an electric vehicle comprising the steps of:
 providing a housing having an inlet for receiving a flow of air therethrough and an outlet in fluid communication with a passenger compartment of the vehicle;   disposing a first heat exchanger in the housing and a second heat exchanger in the housing downstream from the first heat exchanger with respect of a direction of the flow of air;   providing a primary circuit containing a refrigerant therein and configured to operate in at least a cooling mode, a demist mode, and a heating mode, the primary circuit having a compressor, a third heat exchanger, and at least one expansion valve each in fluid communication with the first heat exchanger;   directing the refrigerant to flow through the first heat exchanger in a first direction during the cooling mode and the demist mode and in a second direction during the heating mode; and   providing a secondary circuit in fluid communication with the second heat exchanger and in one of fluid communication with and heat exchange communication with a portion of the primary circuit intermediate the third heat exchanger and the at least one expansion valve.   
     
     
         14 . The method of  claim 13 , further comprising the steps of directing one of the refrigerant and a coolant to flow through the second heat exchanger during the demist mode. 
     
     
         15 . The method of  claim 13 , wherein the primary circuit includes a plurality of valves and a plurality of bypasses cooperating with each other to direct the refrigerant through the first heat exchanger in first direction and the second direction. 
     
     
         16 . The method of  claim 13 , wherein the secondary circuit is in heat exchange communication with the primary circuit, the primary circuit includes a fourth heat exchanger providing the heat exchange communication between the primary circuit and the secondary circuit, the fourth heat exchanger in fluid communication with and adjacent to the third heat exchanger. 
     
     
         17 . The method of  claim 13 , wherein the secondary circuit is in heat exchange communication with the primary circuit and contains a coolant therein, the secondary circuit includes at least one valve and at least one bypass cooperating with each other to direct the coolant to flow through the secondary circuit. 
     
     
         18 . The method of  claim 17 , further comprising the steps of:
 disposing the at least one bypass in heat exchange communication with a battery of the electric vehicle; and   directing the coolant to flow through the bypass of the secondary circuit to transfer heat from the battery to the coolant during at least one of the cooling mode and the heating mode.   
     
     
         19 . The method of  claim 14 , further comprising the steps of:
 providing a fan adjacent the third heat exchanger to convey air through the third heat exchanger; and   adjusting a speed of the fan to control an amount of heat transferred to the air conveyed through the housing by the second heat exchanger.   
     
     
         20 . A method for operating an HVAC system of an electric vehicle comprising the steps of:
 providing a housing having an inlet for receiving a flow of air therethrough and an outlet in fluid communication with a passenger compartment of the vehicle;   disposing a first heat exchanger in the housing and a second heat exchanger in the housing downstream from the first heat exchanger with respect of a direction of the flow of air;   providing a primary circuit containing a refrigerant therein and configured to operate in at least a cooling mode, a demist mode, and a heating mode, the primary circuit having a compressor, a third heat exchanger, and at least one expansion valve each in fluid communication with the first heat exchanger;   directing the refrigerant to flow through the first heat exchanger in a first direction during the cooling mode and the demist mode and in a second direction during the heating mode;   providing a secondary circuit in fluid communication with the second heat exchanger and in one of fluid communication with and heat exchange communication with a portion of the primary circuit intermediate the third heat exchanger and the at least one expansion valve; and   directing one of the refrigerant and a coolant to flow through the second heat exchanger during the demist mode.