Abstract:
A system and method for controlling air flow through a passenger cabin and battery pack of a vehicle having a battery module is disclosed. A HVAC controller communicates with a battery pack controller to assure that air flow from the passenger cabin through the battery pack, and either out to atmosphere or returned to the passenger cabin, is coordinated to obtain desirable passenger cabin heating/cooling and battery cooling.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates generally to a vehicle having a heating ventilation and air conditioning (HVAC) system and an air-cooled battery pack. 
         [0002]    Some modern automotive vehicles are propelled by electric motors, whether a hybrid electric vehicle or a pure electric vehicle. These vehicles include battery packs for storing electric charge used to drive the motor. A significant amount of energy flow into and out of the battery pack can occur, which may raise the temperature of the battery pack above levels that are desirable. Consequently, some of these vehicles use various techniques for cooling the battery pack. Given the additional cost and complexity of cooling a battery pack, it is thus desirable to cool it in the most efficient and least costly way possible. 
       SUMMARY OF THE INVENTION 
       [0003]    An embodiment contemplates a vehicle having a passenger cabin with an HVAC module and a battery module having a battery pack. The vehicle may include a recirculation/fresh air door located in the HVAC module and operable to selectively allow variable proportions of fresh air from outside the vehicle and recirculated air from inside the passenger cabin to flow there-past; a HVAC blower, located in the HVAC module, and operable to draw the air past the recirculation/fresh air door and direct the air into the passenger cabin; a HVAC module controller operatively engaging and controlling a position of the recirculation/fresh air door and a speed of the HVAC blower; a battery pack air inlet configured to direct the air from the passenger cabin into the battery pack; a battery pack blower, located in the battery module, and operable to draw in the air through the battery pack air inlet; and a battery pack controller, operative to control a speed of the battery pack blower, and in communication with the HVAC module controller. 
         [0004]    An embodiment contemplates a method for controlling air flowing into and out of a passenger cabin of a vehicle and the air flowing through a battery pack of a battery module, the method comprising the steps of: controlling a position of a recirculation/fresh air door located in a HVAC module with a HVAC module controller; controlling a speed of a HVAC blower, located in the HVAC module, with the HVAC module controller; controlling a speed of a battery pack blower, located in the battery module, with a battery pack controller; drawing the air from the passenger cabin through the battery pack with the battery pack blower; and communicating from the HVAC module controller to the battery pack controller to selectively coordinate the speed of the battery pack blower with the speed of the HVAC blower. 
         [0005]    An embodiment contemplates a method for cooling a passenger cabin of a vehicle and a battery pack of a battery module while the vehicle is not operating, the method comprising the steps of: controlling a position of a recirculation/fresh air door located in a HVAC module with a HVAC module controller to allow fresh air to be drawn into the passenger cabin; controlling a speed of a battery pack blower, located in the battery module, with a battery pack controller; communicating from the battery pack controller to the HVAC module controller to coordinate the air flow through the passenger cabin; drawing the air from the passenger cabin through the battery pack with the battery pack blower; and exhausting the air from the battery pack blower through an exhaust air outlet to outside of the vehicle. 
         [0006]    An advantage of an embodiment is that a positive passenger cabin pressure may be maintained in all HVAC and battery cooling modes. 
         [0007]    An advantage of an embodiment is that blower noise in the HVAC module may be reduced without reducing the air flow into the passenger cabin by using the battery pack blower to augment the HVAC blower. Moreover, the blower power may be reduced by using air flow from ram air, when the vehicle speed is high enough. 
         [0008]    An advantage of an embodiment is that the blower in the battery pack or HVAC blower may be employed for battery pack and passenger cabin cooling when the vehicle is parked. Thus, even when the vehicle is not operating, the battery (especially during charging) and the passenger cabin can be kept cooler by causing air to flow through them. 
         [0009]    An advantage of an embodiment is that the air distribution in the passenger cabin may be improved by drawing air into the battery pack air inlet. This may result in improved cooling capacity of the HVAC module due to more air flow, or improved heating by using battery heat for supplemental heating in the passenger cabin. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a schematic, side view of a vehicle according to an embodiment. 
           [0011]      FIG. 2  is a schematic view of an air flow duct and controls adjacent to a vehicle battery pack. 
           [0012]      FIG. 3  is a schematic view of a HVAC module and passenger cabin vents. 
           [0013]      FIG. 4  is a schematic, front view of a portion of a rear vehicle seat according to a second embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]      FIGS. 1-3  illustrate a vehicle  10  according to a first embodiment. The vehicle  10  includes a passenger cabin  12 , a front portion  14 , which may contain an engine or motor (not shown), and a rear portion  16 , which may be a trunk or rear cargo portion and contains a battery module  18 . The basic vehicle architecture may be a hybrid electric, electric, or other similar type of vehicle propulsion architecture where a battery module  18  is employed. 
         [0015]    The passenger cabin  12  may include front seats  20  and rear seats  22 . A package shelf  24  may be mounted behind the rear seats  22  and include a battery pack air inlet  26 , which may be designed to allow flow in only one direction—out of the passenger cabin  12 . Seat support structure  28  may be located under the rear seats  22  and include a return air outlet  30 . An instrument panel  32  may be located in the passenger cabin  12  and include a heating, ventilation and air conditioning (HVAC) module  34  mounted behind or underneath it. 
         [0016]    The HVAC module  34  may include a HVAC blower  36 , driven by a blower motor  38 , that can draw in air from a recirculation air intake  40  and a fresh air intake  42  and direct it toward an evaporator  44 . Air directed toward the evaporator  44  may be directed through or around a heater core  46  before being directed through one or more of a defrost vent  48 , an upper vent  50  and a foot vent  52 . 
         [0017]    The HVAC module  34  may also include a HVAC module controller  54  having controller communication lines  56  to a recirculation/fresh air door  58 , a defrost door  60 , an upper vent door  62 , a foot vent door  64 , and a heater core door  66 . The doors can be electronically controlled to pivot to open, closed or positions in between, to draw in and direct the air where desired, as is known to those skilled in the art. The HVAC module controller  54  may also communicate with the blower motor  38  to cause it to be driven at a desired speed. The communication lines in  FIGS. 1-3  are indicated by dashed lines and may carry signals via copper, fiber optic, radio wave transmission, or any other suitable means for transmitting the signals. The HVAC module controller  54  may also communicate with a battery pack controller  70  via a communication line  68 . 
         [0018]    The battery pack controller  70  may be part of the battery module  18 . While the battery pack controller  70  is shown adjacent to a battery pack  80  (discussed below), it may be located somewhere else in the vehicle  10 , if so desired. The battery pack controller  70  also controls an exhaust/return air door  72 , which controls flow to a return air outlet  30  and an exhaust air outlet  74 . A battery pack blower  76  is also controlled by the controller  70 . The battery pack blower  76  may be located in the battery pack  80  or separated from the battery pack  80 , but connected by an air duct. The blower  76  draws air in through the battery pack air inlet  26 , through the battery pack  80 , and pushes it into an airflow duct  78 , where it is directed out through the return air outlet  30  or the exhaust air outlet  74 . The air flow through the battery pack  80  helps remove heat from the battery pack  80 . The battery module  18  may also include a temperature sensor  82  that communicates with the battery pack controller  70  to provide input relating to the temperature in the battery pack  80 . While the return air outlet  30  directs the air from the battery pack  80  back into the passenger cabin  12 , the exhaust air outlet  74  directs the air out of the vehicle  10  into the atmosphere. 
         [0019]    One will note that the battery pack  80  is cooled by air drawn from the passenger cabin  12  that flows through it. If the HVAC module  34  is operating, then the air supplied to cool the battery pack  80  is, in effect, supplied by the HVAC module  34 . With this overall configuration, the conventional body mounted cabin pressure relief valve (not shown), may be eliminated or designed with flaps that are designed to open at a higher pressure. 
         [0020]    The vehicle  10  having the HVAC module  34  and battery module  18  discussed above can be operated in various modes to provide multiple different functions relating to cooling or heating the passenger cabin  12  and cooling the battery pack  80 . The possible directions for air flow in the various modes of operation are indicated by the phantom-line arrows shown in  FIGS. 1-3 . The movement of the various doors, which are employed to direct the air flow, are indicated by the curved double-arrow-ended lines in  FIGS. 2 and 3 . 
         [0021]    Different modes of operating the HVAC module  34  in cooperation with the battery module  18  will now be discussed. By coordinating the operation of the two modules  18 ,  34 , greater operating efficiencies and better performance may be achieved. 
         [0022]    A first operating mode is one where the HVAC module  34  is providing typical heating or cooling to the passenger cabin  12 , and the battery module  18  is providing cooling to the battery pack  80  and exhausting the air through the exhaust air outlet  74 . The HVAC module controller  54  communicates with the battery pack controller  70  to ensure that the battery pack blower  76  will not draw more air than the HVAC blower  36 , thus assuring that the passenger cabin  12  will not have a negative pressure (i.e., less than atmospheric). If the battery pack blower  76  needs to draw a larger volume of air to cool the battery pack  80 , then the HVAC controller  54  can increase the HVAC blower  36  speed and make any other corresponding adjustments needed to assure that HVAC module  34  maintains the passenger cabin  12  at the desired temperature. If the HVAC module  34  is in a heat operating mode, rather than air conditioning, then the exhaust/return air door  72  may be adjusted to return some or all of the air to the passenger cabin  12 . Also, if the HVAC module  34  is in recirculation mode while operating the air conditioner, and battery pack cooling is required, then the HVAC controller  54  can shift the recirculation/fresh air door  58  to less than full recirculation. The amount of fresh air intake would be a function relating to the speeds of the HVAC blower  36  and the battery pack blower  76  in order to assure that a positive pressure is maintained in the passenger cabin  12 . 
         [0023]    A second operating mode is one where the vehicle  10  is traveling fast enough to have a ram air effect when fresh air is being drawn into the HVAC module  34 . This may include a HVAC blower speed reduction that increases with increased vehicle speed. This may also allow for a corresponding decrease in the battery pack blower  76  as well. 
         [0024]    A third operating mode is one where a maximum cooling is desired from the HVAC module  34 . With the HVAC blower  36  operating at maximum speed, the battery pack blower  76  can be increased in speed (with the exhaust/return air door  72  sending air through the exhaust air outlet  74 ) in order to maximize the air flow through the passenger cabin  12 . 
         [0025]    A fourth operating mode is one the where battery pack blower  76  is used to assist the HVAC blower  36  in order to allow the HVAC blower  36  to operate at a lower speed, reducing the noise emanating from the HVAC module  34 . That is, when moderate to high blower speeds are needed from the HVAC blower  36 , the battery pack blower  76  can be increased in speed to help increase the air flow through the passenger cabin  12 , thus reducing the speed at which the HVAC blower  36  needs to operate to obtain the desired heating or cooling effect. 
         [0026]    A fifth operating mode is one where improved air distribution throughout the passenger cabin  12 —especially to passengers in the rear seats  22 —is achieved. When providing air conditioning to the passenger cabin  12 , the exhaust/return air door  72  is set to direct air through the exhaust air outlet  74  and the battery pack blower  76  is activated. Thus, the cool air emanating from the HVAC module  34  is drawn past the rear seat passengers as it flows into the battery pack air inlet  26 . When providing heat to the passenger cabin  12 , the exhaust/return air door  72  is set to direct air through the return air outlet  30  and the battery pack blower  76  is activated. Thus, not only is the warm air emanating from the HVAC module  34  drawn past the rear seat occupants, but the air flowing through the battery pack  80  absorbs heat and is returned to the feet of the rear seat passengers via the return air outlet  30 . 
         [0027]    A sixth operating mode is one where the battery pack blower  76  is operated when the vehicle is parked and the ambient temperature is high (e.g., the car is parked in the sun on a hot summer day). With the exhaust/return air door  72  set to direct air flow through the exhaust air outlet  74 , and the recirculation/fresh air door  58  at least partially open to the fresh air intake  42 , the battery pack blower  76  is operated. This will cause air to be drawn in through the fresh air intake  42 , through the passenger cabin  12 , through the battery pack  80 , and out into the atmosphere. The battery pack blower  76  can be operated at a low speed so as to avoid draining the battery pack too much. The small flow of air is sufficient to help reduce the heat build-up in the passenger cabin  12  and battery pack  80 . This allows for increased passenger comfort upon entry into the passenger cabin  12  as well as reducing the temperature inside the battery pack  80 . This operating mode may also be used if the battery pack  80  is plugged-in for recharging. The air flow through the battery pack  80  will help reduce heat build-up that may occur during battery charging. 
         [0028]    A seventh operating mode is one where the battery pack temperature is higher than the passenger cabin  12  and the engine coolant has not warmed enough to allow the heater core  46  to be fully effective. In this operating mode, the exhaust/return air door  72  is moved to direct the air flow through the return air outlet  30  and the battery pack blower  76  is operated. Thus, air is drawn in from the passenger cabin  12  through the battery pack air inlet  26 , absorbs heat as it flows through the battery pack  80 , and is directed back into the passenger cabin  12  through the return air outlet  30 . In effect, a supplemental heat is provided until the heater core  46  can produce the heat needed by the HVAC module  34 . 
         [0029]    An eighth operating mode is one where the front HVAC module  34  is operating in full recirculation mode, in which case the battery module  18  would be returning the air back into the passenger cabin  12  in order to avoid creating a negative pressure therein. If this occurs while the battery pack  80  has high thermal loads, then the HVAC module controller  54  may coordinate with the battery pack controller  70  to move the recirculation/fresh air door  58  to at least partial fresh air intake  42  and the exhaust/return air door  72  to at least partial exhaust air outlet  74 . This will avoid returning excessive heat from the battery pack  80  to the passenger cabin  12  while also avoiding a negative pressure therein. 
         [0030]      FIG. 4  illustrates a second embodiment. In this embodiment, elements that are similar to those in the first embodiment will have similar element numbers, but in the 100-series. The rear seats  122 , having a rear seat back  186  and rear seat bottom  188  supported by a seat support structure  128 , may provide for both air intake and return from a battery pack (not shown in this embodiment). A battery pack air intake  126  may be located in the seat support structure  128  (rather than in the package shelf), and a return air outlet  130  may also be located in the seat support structure  128 , spaced from the intake  126 . This may be more practical for vehicles having a rear cargo space rather than a rear package shelf and trunk. 
         [0031]    For another alternative embodiment (not shown), the air may be drawn into the battery pack from the package shelf or from under the rear seat, with the air returning from the battery pack directed through the package shelf back into the passenger cabin. In yet another alternative embodiment (not shown), for vehicles having a rear cargo area rather than trunk and package shelf, such as in a station wagon or other similar type of vehicle, the battery pack air inlet and return air outlet may be in one or both side walls of this rear cargo area. And, of course, the battery pack can be located above or below a vehicle floor pan, as is desired for the particular vehicle configuration. 
         [0032]    While certain embodiments of the present invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.