Abstract:
A hybrid electric vehicle includes an internal combustion engine and an electrical power storage unit. The engine and power storage unit are configured to provide motive power for the vehicle. The vehicle also includes a heater core in fluid communication with the engine, power storage unit and vehicle&#39;s cabin.

Description:
BACKGROUND 
     It is a known design practice to use a heater core, a radiator-like device, for heating a cabin of a vehicle. Hot coolant from the vehicle&#39;s engine may be passed through a winding tube of the core (a heat exchanger between coolant and cabin air.) Fins attached to the core tubes may increase the surface area for heat transfer to air that is forced past them by a fan, for example, to heat the passenger compartment. 
     Once the engine has warmed up, the coolant may be kept at a generally constant temperature in a known fashion by a closed-loop control system that includes a thermostat. The temperature of air entering the vehicle&#39;s cabin may be controlled by a valve that limits the amount of coolant passing through the heater core. Alternatively, the heater core may be blocked off, or partially blocked off, by a valve that directs part or all of the incoming air around the heater core. Some systems allow a driver to control the valve directly by means of, for example, a rotary knob or lever. Other systems may use electronics to control the valve. 
     Vehicles with dual climate control functions (allowing a driver and passenger to each set a different temperature) may use a heater core split in two, where different amounts of coolant may flow through the heater core on either side of the split to obtain the desired heating. 
     Because the heater core cools the heated coolant from the engine, it may act as a secondary radiator for the engine. If the primary radiator is working improperly, an operator may turn the heat on in the passenger cabin, resulting in some cooling of the engine. 
     SUMMARY 
     A hybrid electric vehicle includes an internal combustion engine and an electrical power storage unit. The engine and power storage unit are configured to provide power for moving the vehicle. The vehicle also includes a heater core, a first fluid line connecting the heater core and engine, and a second fluid line connecting the power storage unit, heater core and vehicle&#39;s cabin. The heater core is configured to transfer heat between the first fluid line and the second fluid line. 
     A hybrid electric vehicle includes an internal combustion engine and an electrical power storage unit. The engine and power storage unit are configured to provide power for moving the vehicle. The vehicle also includes a heater core in fluid communication with the engine, power storage unit and vehicle&#39;s cabin. 
     A method for managing heat in a hybrid electric vehicle includes passing a first fluid over one of an engine and traction battery to transfer heat to the first fluid, transferring the heat from the first fluid to a second fluid, and passing the second fluid over the other of the engine and traction battery. 
     While example embodiments in accordance with the invention are illustrated and disclosed, such disclosure should not be construed to limit the invention. It is anticipated that various modifications and alternative designs may be made without departing from the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a hybrid electric vehicle according to an embodiment of the invention. 
         FIG. 2  is a block diagram of a hybrid electric vehicle according to another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIG. 1 , an embodiment of a hybrid electric vehicle  10  may include an engine  12 , radiator  14  and heater core  16 . The vehicle  10  may also include a traction battery  18  (or other suitable electrical power storage device), controller  20  and cabin  22 . As known in the art, the engine  12  may provide power for moving the vehicle  10 ; the traction battery  18  may also provide power for moving the vehicle  10  (via an electric machine). 
     The engine  12 , radiator  14  and heater core  16  are connected via a fluid loop  24 , e.g., piping. The heater core  16 , traction battery  18 , cabin  22  and exterior of the vehicle  10  are connected via a fluid line  26 , e.g., an air duct. The fluid line  26  includes a valve  29  that may direct fluid to the cabin  22  and/or exterior of the vehicle  10 . The controller  20  may selectively control the valve  29 . As apparent to those of ordinary skill in the art, pumps, blowers, etc., (not shown) may be used to move the fluids within the fluid loop  24  and/or fluid line  26 . The controller  20  may also selectively control these pumps, blowers, etc. (It is assumed that such techniques for moving the fluids within the fluid loop  24  and/or fluid line  26  are known and need not be discussed in further detail.) 
     The fluid loop  24  may direct fluid, e.g., a coolant, that receives heat from the engine  12  (thus raising the temperature of the coolant) to cool the engine  12  and carries this heat to the radiator  14 . The radiator  14  may then dissipate the heat (thus lowering the temperature of the coolant.) Similarly, the fluid may carry heat from the engine  12  to the heater core  16 . The heater core  16  may transfer this heat to air in the fluid line  26 . This heated air may then be used to heat the cabin  22 . 
     The fluid line  26  may direct fluid, e.g., air, that receives heat from the traction battery  18  (thus raising the temperature of the air) to cool the traction battery  18  and carries this heat to the heater core  16 . As discussed in more detail below, the heater core  16  may or may not transfer this heat to the fluid in the fluid line  24 . This heated air may then be used to heat the cabin  22  and/or exhausted to the exterior of the vehicle  10  by selective control of the valve  29 . Heating the cabin  22  with heat generated by the traction battery  18  may reduce the need to start the engine  12  for the purpose of heating the cabin  22 . 
     As discussed above, heat generated by the engine  12  and/or traction battery  18  may be used to heat the cabin  22 . Heat generated by the traction battery  18 , however, may also be used to heat the engine  12 . For example, heat generated by the traction battery  18  may be transferred to the fluid in the fluid loop  24  via the heater core  16  (provided the temperature of the fluid in the fluid loop  24  is less then the temperature of the air in the fluid line  26 ). The fluid in the fluid line  24  may then be used to pre-heat the engine  12  (provided the temperature of the fluid in the fluid loop  24  is greater than the temperature of the engine  12 ) prior to engine start to, for example, improve cold start emissions of the engine  12 . Similarly, the fluid in the fluid line  24  may be used to indirectly raise the operating temperature of the engine  12 . (Because the fluid in the fluid line  24  will have a higher temperature, the rate of heat transfer from the engine  12  to the fluid in the fluid loop  24  will be less than otherwise.) Higher operating temperatures of the engine  12  may raise exhaust temperatures, which in turn may reduce or eliminate the need for post-injection of fuel into the combustion chamber (not shown) for particulate filter “light-off” and regeneration. 
     Likewise, heat generated by the engine  12  may be used to heat the traction battery  18 . For example, heat generated by the engine  12  may be transferred to the air in the fluid line  26  via the heater core  16  (provided the temperature of the fluid in the fluid loop  24  is greater than the temperature of the air in the fluid line  16 ). This heated air may then be directed over the traction battery  18  (using, for example, any suitably configured blower). Such heating may reduce, for example, the tendency of the traction battery  18  to become power limited due to low internal cell temperatures in cold environments. 
     The controller  20  may act to operate the elements as described above based on, for example, user input to a climate control system (not shown) and temperature readings from temperature sensors (not shown) associated with the engine  12 , traction battery  18 , fluid loop  24 , etc. (It is assumed that such techniques for receiving such input and detecting such temperatures are known and need not be discussed in further detail.) As an example, the controller  20  may receive a command to heat the cabin  22 . The controller  20  may then determine whether to use heat which has been generated by the engine  12  and/or traction battery  18  based on whether the engine  12  and/or traction battery  18  have heat available to reject. If the engine  12  is “off” (no heat available), the controller  20  may operate a suitably configured blower (not shown) to provide heat generated by the traction battery  18  to the cabin  22  via the fluid line  26 . As another example, the controller  20  may receive a command to pre-heat the engine  12  prior to a cold start. The controller  20  may operate a suitably configured pump (not shown) in the fluid line  24  and a suitably configured blower (not shown) in the fluid line  26  such that heat generated by the traction battery  18  is transferred to the fluid in the fluid line  24  via the heater core  16 . This heat may then be carried by the fluid in the fluid line  24  to the engine  12 . Other control scenarios are also possible. 
     Referring now to  FIG. 2 , numbered elements that differ by 100 relative to the numbered elements of  FIG. 1  have similar, although not necessarily identical, descriptions to the numbered elements of  FIG. 1 . Another embodiment of a hybrid electric vehicle  110  may include an engine  112 , radiator  114  and heater core  116 . The vehicle  110  may also include a traction battery  118 , controller  120  and cabin  122 . 
     The engine  112 , radiator  114  and heater core  116  are fluidly connected via a fluid loop  124 . The fluid loop  124  includes valves  130 ,  132 ,  134  that, as discussed below, may be used to bypass the engine  112  and/or radiator  114 . In other embodiments, however, any suitable valving arrangement is possible. The heater core  116 , traction battery  118 , cabin  122  and exterior of the vehicle  110  are fluidly connected via a fluid line  126 . The fluid line  126  includes a valve  129  that may direct fluid to the cabin  122  and/or exterior of the vehicle  110 . The controller  120  may selectively control the valves  129 ,  130 ,  132 ,  132 . As mentioned above, pumps, blowers, etc., (not shown) may be used to move the fluids within the fluid loop  124  and/or fluid line  126 . The controller  120  may also selectively control these pumps, blowers, etc. 
     As discussed with reference to  FIG. 1 , heat generated by the engine  112  and/or traction battery  118  may be used to heat the cabin  122 , heat generated by the traction battery  118  may be used to heat the engine  112 , and heat generated by the engine  112  may be used to heat the traction battery  118 . The selective control of the valves  130 ,  132 ,  132 , however, in possible combination with the techniques described above may provide further control over the heat transfer between the engine  112 , traction battery  118  and/or cabin  122 . As an example, the controller  120  may actuate the valve  130  to reduce the flow rate of coolant to the engine  112  to reduce the rate of heat transfer from the engine  112  to the coolant in the fluid line  124 . This may raise the operating temperature of the engine  112  and thus raise exhaust temperatures for filter “light-off.” As another example, the controller  120  may actuate the valves  130 ,  132  to bypass the engine  112  to raise the operating temperature of the engine  112 . As yet another example, the controller  120  may actuate the valves  130 ,  134  to bypass the engine  112  and the radiator  114 . This may allow the heater core  116  to substantially raise the temperature of the fluid in the fluid loop  124  with heat generated by the traction battery  118  prior to pre-heating the engine  112  before a cold start. Other scenarios and arrangements are, of course, also possible. 
     While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.