Abstract:
A vehicle having a vehicle interior may comprise a backlight having an interior surface and a solar load reduction system. The solar load reduction system may include a louver support supported by the vehicle structure, a plurality of pivotable louvers located in the vehicle interior, each of the louvers may be pivotally mounted to the louver support and spaced from the other louvers, and a tilting mechanism adjacent to the backlight and operatively engaging the plurality of louvers to selectively cause the louvers to pivot relative to the louver support. A pane of translucent material may enclose the louvers in a cavity between the pane and backlight.

Description:
BACKGROUND OF INVENTION 
       [0001]    The present invention relates generally to a solar load reduction device and more particularly to louvers mounted inside a vehicle backlight. 
         [0002]    A significant emphasis is being placed on improving the fuel economy of automotive vehicles while maintaining or improving passenger comfort. One area in particular where fuel economy and passenger comfort can be adversely affected is with the solar load on the interior of a vehicle due to sun light shining through the vehicle windows. This solar load increases the load on the air conditioning system when cooling the vehicle interior. One window in particular, the vehicle backlight, can contribute significantly to the solar load on a vehicle parked in the sun. 
         [0003]    Some have attempted to reduce this solar load through the use of thin, horizontally extending louvers fixed adjacent to the inside or outside of the backlight. Being fixed horizontally, the thin louvers still allow a vehicle operator to see out of the back window, while the horizontal width of each louver will reflect some of the solar load, thus reducing the heat load on the vehicle interior. However, for externally mounted louvers, the aerodynamics of the vehicle may be adversely affected. Moreover, for both interior and exterior mounted louvers, the solar load is only partially reduced, especially when the sun is not directly overhead. 
       SUMMARY OF INVENTION 
       [0004]    An embodiment contemplates a vehicle having a vehicle structure defining a vehicle interior comprising a backlight supported by the vehicle structure and having an interior surface facing into the vehicle interior, and a solar load reduction system. The solar load reduction system may include a louver support supported by the vehicle structure, a plurality of pivotable louvers located in the vehicle interior adjacent to the interior surface, with each of the louvers pivotally mounted to the louver support and spaced from the other louvers, and a tilting mechanism adjacent to the backlight and operatively engaging the plurality of louvers to selectively cause the louvers to pivot relative to the louver support, whereby the louvers can be rotated between an open position allowing for a horizontal view through the louvers and the backlight and a closed position where the horizontal view through the louvers is blocked. 
         [0005]    An embodiment contemplates a vehicle, having a vehicle structure defining a vehicle interior, comprising a backlight supported by the vehicle structure and having an interior surface facing into the vehicle interior, and a solar load reduction system. The solar load reduction system may include a louver support supported by the vehicle structure, a plurality of louvers located in the vehicle interior adjacent to the interior surface, with each of the louvers mounted to the louver support and spaced from the other louvers and oriented to allow for a horizontal view through the louvers, and an interior pane of translucent material supported by the vehicle structure in the vehicle interior, spaced from the backlight and adjacent to the plurality of louvers to thereby form a cavity within which the plurality of louvers are located. 
         [0006]    An advantage of an embodiment is that the solar load transmitted through the backlight into the vehicle is reduced, which lowers the energy required to cool the vehicle interior to an acceptable temperature for occupants and other vehicle components that may require temperature management (such as a battery pack for a hybrid or electric vehicle). This reduced solar load is accomplished with minimal power consumed, minimal increase in vehicle mass and without increasing the aerodynamic drag of the vehicle. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0007]      FIG. 1  is a schematic, block diagram of a vehicle solar load reduction system. 
           [0008]      FIG. 2  is a schematic, perspective view of a portion of an exterior of a vehicle having the vehicle solar load reduction system. 
           [0009]      FIG. 3  is a schematic, sectional view of a portion of the vehicle, with the solar load reduction system in the open position. 
           [0010]      FIG. 4  is a schematic view similar to  FIG. 3 , but with an added interior pane and the solar load reduction system in a partially closed position. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]      FIGS. 1-3  illustrate portions of a vehicle, indicated generally at  20 , that includes a solar load reduction system  22 . The system  22  is adjacent to a backlight  24  (that is, the back window of the vehicle) in the vehicle interior  26 . The system  22  includes a set of pivotable louvers  28  adjacent to an interior surface  30  of the backlight  24  that extend side-to-side essentially between the two rear roof pillars  32  and are spaced essentially from the vehicle roof  34  to a rear panel  36  of the vehicle  20 , such as a rear package shelf in a sedan—although, the pivotable louvers  28  may be employed with other styles of vehicles as well. 
         [0012]    Each of the louvers  28  is long and slender, extending horizontally from side-to-side, generally following the curvature of the interior surface  30  of the backlight  24 . A pair of louver supports  38  mount at their lower ends to structure such as the rear panel  36  and at their upper ends to structure such as the roof  34 . The louver supports  38  mount to each louver  28  at pivot joints  40  that support the louvers  28  in spaced relation to each other and allow for pivoting of the louvers  28  relative to the louver supports  38 . The thickness of each louver  28  is preferably small, just enough to maintain the desired stiffness of each louver, in order to minimize the loss in visual field (in a horizontal direction) through the backlight  24  when the louvers  28  are in the open position (see  FIG. 3  for louvers shown in the open position). The width of each louver  28  is preferably just sufficient so that the louvers overlap somewhat when in the closed position (see  FIG. 4  for louvers shown in the partially closed position) in order to block most if not all of the solar load entering though the backlight  24 . They may be somewhat thicker or wider for esthetic reasons or to obtain better solar load blockage when the louvers  28  are in the open position, but the tradeoff is that this will add more weight to the vehicle  20 . Each of the louvers  28  may be covered with an infrared reflective coating to better reflect the solar load back out of the vehicle  20  through the backlight  24 . Such a coating may be, for example, a polished metal, a mirror coating or some other type of coating that reflects the solar load back out of the vehicle  20 . Alternatively, each of the louvers  28  may be covered with solar cells to provide power for actuation of the louvers  28  in a self-powered system. 
         [0013]    The solar load reduction system  22  also includes a tilting mechanism  42  that may include, for example, a tilting arm  44  that connects to each of the louvers  28  at locations spaced from the pivot joints, and a motor assembly  46  that is connected to and drives the tilting arm  44 . As the motor assembly  46  is driven in one direction, the tilting arm  44  will cause each of the louvers  28  to pivot toward a closed position where the louvers lay on top of each other to fully reflect the solar load coming in through the backlight  24 . As the motor assembly  46  is driven in the other direction, the tilting arm  44  will cause each of the louvers  28  to pivot to a generally horizontal position (the open position) where the blockage of the driver&#39;s view horizontally through the backlight  24  is minimized while still allowing for reflection of some of the solar load when the sun is more overhead in the sky (i.e., block sun light directed in a more vertical direction). Other types of tilting mechanisms may be employed instead, if so desired. Thus, when referring to a “motor assembly” herein, this includes other types of actuators that can be used to tilt the louvers back and forth. 
         [0014]    The solar load reduction system  22  may also include a controller  50  that controls the operation of the motor assembly  46 , and either or both of a solar load sensor  52  and a louver switch  54 , which may be mounted on an instrument panel  56 . The controller may be a stand alone device or may be part of a larger controller, such as a body control module or powertrain control module. The solar load sensor  52  may be mounted, for example, on the instrument panel  56  or the rear panel  36  in the vehicle interior  26 . If equipped with a solar load sensor  52 , the controller  50  may detect when the vehicle has been shut off for a predetermined time, for example, and if the solar load indicated by the solar load sensor  52  is above a predetermined threshold, activate the motor assembly  46  to tilt the louvers  28  to the closed position, thus minimizing the solar load entering the vehicle interior  26  through the backlight  24 . 
         [0015]    In addition, the louver switch  54  may be actuated by a vehicle occupant to activate the motor assembly  46  to tilt the louvers  28  to the closed position even if the solar load sensor  52  does not detect a high level of solar load. In this case, the switch  54  may be a three position switch, with one position that allows the controller  50 , with input from the solar load sensor  52  (among other sensors), to determine the appropriate position for the louvers  28 , a second position to override the solar load sensor  52  to cause the louvers  28  to open and stay opened and a third position to cause the louvers  28  to close and stay closed. Alternatively, if the louver switch  54  is connected to the motor assembly  46  via the controller  50 , then the controller  50  may be optionally programmed to prevent louver closure while the vehicle  20  is running, even if the louver switch  54  is actuated to the louver closed position. 
         [0016]    Alternatively, there may be no solar load sensor in the vehicle  20 , and the louver switch  54  may be connected directly to the motor assembly  46  and pivot the louvers  28  to the opened or closed position based solely on the position the vehicle occupant places the louver switch  54 . In this case, the louver switch  54  may be a two position switch. In another alternative, there may be no louver switch  54  and the position of the louvers  28  is then determined by the controller  50  based on the solar load sensor  52  and the state of other vehicle parameters. 
         [0017]      FIG. 4  illustrates a schematic, sectional view of a portion of the vehicle  20 , with the solar load reduction system  22  in a partially closed position, and with the addition of an optional interior pane  60  of translucent material. The interior pane  60  is mounted in the vehicle interior  26  and generally parallels the backlight  24 . This forms a cavity  62  between the backlight  24  and the interior pane  60  within which are mounted the louvers  28 . The louvers  28  may still be pivotable by a tilting mechanism  42 , if so desired, to allow for improved solar load reduction control. In this instance, the interior pane  60  allows for pivoting of the louvers  28  while preventing a object (not shown) sitting on the rear panel  36  (such as a package shelf) from interfering with the pivoting motion. The interior pane  60  also blocks any objects from striking and breaking the louvers  28 . 
         [0018]    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.