Abstract:
A vehicle glazing panel assembly has a polycarbonate panel supported by a vehicle body, and has a plurality of peripheral regions. A reinforcement member is mounted to the polycarbonate panel proximate at least one of the plurality of peripheral regions to stiffen the polycarbonate panel. A method of manufacturing a vehicle glazing panel assembly thermoforms a polycarbonate panel. A reinforcement member is injection molded. The reinforcement member is joined to the polycarbonate panel to stiffen the polycarbonate panel. A vehicle glazing panel assembly is manufactured by a method of thermoforming. A reinforcement member is formed and joined to the polycarbonate panel to stiffen the polycarbonate panel.

Description:
BACKGROUND 
     1. Technical Field 
     Various embodiments relate to semi-structural polycarbonate panel assemblies for vehicles. 
     2. Background 
     Polycarbonate panel assemblies are becoming extremely advantageous in various fields of endeavor, such as in the automotive vehicle field, because polycarbonate glazing has a relatively low weight compared to glass. Replacing glass with polycarbonate glazing, however, often requires either using a substantially thicker piece of polycarbonate or applying a stiffener to the polycarbonate to reach an equivalent stiffness to that of the glass panel it is replacing. The stiffener can be applied to the polycarbonate panel in a two shot molding process. This process, however, requires expensive tooling and specialized molding machines. 
     SUMMARY 
     In one embodiment, a vehicle glazing panel assembly is disclosed. The vehicle glazing panel assembly has a polycarbonate panel adapted to be supported by a vehicle body and having a plurality of peripheral regions. A reinforcement member is mounted to the polycarbonate panel proximate at least one of the plurality of peripheral regions to stiffen the polycarbonate panel. 
     In another embodiment, a method of manufacturing a vehicle glazing panel assembly is provided. A polycarbonate panel having a plurality of regions is thermoformed. A reinforcement member is injection molded. The reinforcement member is joined to the polycarbonate panel proximate at least one of the plurality of regions of the polycarbonate panel to stiffen the polycarbonate panel. 
     In another embodiment, a vehicle glazing panel assembly is disclosed. The vehicle glazing panel assembly is manufactured by a method including thermoforming a polycarbonate panel having a plurality of regions. A reinforcement member is injection molded. The reinforcement member is joined to the polycarbonate panel proximate at least one of the plurality of regions of the polycarbonate panel to stiffen the polycarbonate panel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a vehicle glazing panel assembly; 
         FIG. 2  is a cross-sectional view of a portion of the vehicle glazing panel assembly of  FIG. 1  taken along line  2 - 2 ; 
         FIG. 3  is a cross-sectional view of a portion of the vehicle glazing panel assembly of  FIG. 1  taken along the line  3 - 3 ; 
         FIG. 4  is a perspective view of another embodiment of a vehicle glazing panel assembly; and 
         FIG. 5  is a cross-sectional view of a portion of the vehicle glazing panel assembly of  FIG. 4  taken along the line  5 - 5 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for the claims and/or as a representative basis for teaching one skilled in the art to variously employ the present invention. 
     One embodiment described herein is shown in  FIG. 1 . In  FIG. 1 , a vehicle roof assembly is illustrated and generally referenced by numeral  10 . The vehicle roof assembly  10  is adapted to be mounted to a vehicle body to cover a vehicle interior. The vehicle roof assembly  10  may enclose an entire vehicle interior or only a portion of the vehicle interior. The vehicle roof assembly  10  may be adapted to be mounted within the vehicle as a vehicle sunroof assembly. In at least one embodiment, the vehicle roof assembly  10  is adapted to be a side window assembly on a side of a vehicle. In another embodiment, the vehicle roof assembly  10  is adapted to be a liftgate or backlight assembly on a rear end of the vehicle. Of course, the vehicle roof assembly  10  may be any vehicle glazing panel assembly that is a generally flat panel. 
     Currently, size, complexity and desirability of vehicle roof assemblies continues to grow. Prior art roof assemblies often utilize glass roof assemblies. With increased amounts of glass utilized for the roof assembly, the total vehicle weight and the weight proximate the top of the vehicle both increase when compared to a vehicle with a metal roof assembly. The increased weight caused by the glass roof assembly also increases the center of gravity for the vehicle and decreases vehicle fuel economy. The additional weight of the glass roof assembly can also increase cost of other related systems, such as the suspension. Replacing the glass roof assembly with a polycarbonate panel can reduce the weight of these systems by as much as 30-40%. 
     A number of technical difficulties prohibit a simple polycarbonate for glass material substitution. One of the main issues is stiffness of the polycarbonate. Since roof panels have relatively little contour, the roof panels should be able to be thermoformed. A thermoformed polycarbonate roof panel, however, will not meet stiffness requirements for the roof assembly without using a substantially thicker panel than the glass it replaces because the material stiffness of polycarbonate is less than the material stiffness of glass and metals. To reproduce the stiffness of glass roof panels with a sufficiently thin polycarbonate roof panel, a ring can be joined on the polycarbonate panel. Consequently, the roof assembly including a polycarbonate panel and a structural back-molded ring can be attempted to be manufactured through multi-shot injection molding. 
     Unfortunately, injection molds for large, optically transparent polycarbonate roof panels including a structural back-molded ring are expensive compared to tooling cost for glass roof panels. Since roof assemblies are not standard vehicle equipment, amortization of tooling cost over the small volume polycarbonate roof panel output greatly increases individual cost of the roof assembly to a customer. Consequently, implementation of a stiff polycarbonate roof assembly is difficult at an acceptable cost. Therefore, the roof assembly  10  according to the multiple embodiments of the present invention, including the polycarbonate panel  12  and a separately formed reinforcement member  14  joined on the polycarbonate panel  12 , is desired. 
     The polycarbonate panel  12  may be thermoformed into a desired shape. As illustrated in  FIG. 1 , the polycarbonate panel  12  has a rectangular shape, with four peripheral regions  16 . The peripheral regions  16  may be straight or curved. Of course, the polycarbonate panel  12  can have any desired shape and/or size so that the polycarbonate panel  12  can be mounted to different locations on a vehicle. 
     The reinforcement member  14  may be injection molded separately from the polycarbonate panel  12  and may be formed as one or more separate pieces. As illustrated, the reinforcement member  14  is joined to the polycarbonate panel  12  proximate each of the peripheral regions  16  to increase stiffness of the polycarbonate panel  12 . 
     The reinforcement member  14  is provided proximate each of the four peripheral regions  16  of the polycarbonate panel  12 . Joining the reinforcement member  14  to the polycarbonate panel  12  proximate the four peripheral regions  16  increases stiffness of the polycarbonate panel  12  overall. 
     As depicted in  FIGS. 2-3 , the reinforcement member  14  may be formed with a metal layer  22  and one or more thermoplastic or thermoplastic composite layers  24 . The metal layer  22  may be formed within only a portion of the reinforcement member  14 , as shown in  FIG. 2 , to locally increase stiffness of the reinforcement member  14  in a desired area of the polycarbonate panel  12 . In another embodiment, multiple thermoplastic layers  24  may be over-molded to the metal layer  22 , as illustrated in  FIG. 3 . 
     Once each the polycarbonate panel  12  and the reinforcement member  14  is formed, the reinforcement member  14  is joined to the polycarbonate panel  12 . In at least one embodiment, the reinforcement member  14  is attached to the polycarbonate panel  12  at attachment joints  32  via laser welding. Laser welding the reinforcement member  14  to the polycarbonate panel  12  presents many benefits. Consumables, such as adhesives, are not necessary to bond the polycarbonate panel to the reinforcement member  14 , which reduces both the cost and weights of the vehicle roof assembly  10  when compared to a bonded roof assembly. Quality of the attachment joints  32  between the polycarbonate panel  12  and the reinforcement member  14  can be tested and verified at the time of manufacture, which is not possible if adhesive bonding is utilized. Additionally, the inability to verify the quality of the adhesive bond presents an undesirable potential risk to the customer. Furthermore, surface preparation is not needed prior to joining the reinforcement member  14  to the polycarbonate panel  12 , which further reduces cost of the roof assembly  10  compared to a bonded assembly. Also, bonding hardware and other features on the back side of polycarbonate can cause visual defects called bond-line read-through, which is not desired. Laser welding the reinforcement member  14  to the polycarbonate panel  12  does not create this defect. Thus, laser welding the reinforcement member  14  to the polycarbonate panel  12  may present numerous advantages. 
     As illustrated in  FIGS. 2-3 , the reinforcement member  14  has a cross-section to provide increased stiffness when attached to the polycarbonate panel  12 . In  FIG. 2 , an embodiment of a cross-section of the reinforcement member  14  attached to the polycarbonate panel  12  is depicted. A first thermoplastic layer  24  is formed having a T-shaped cross-section. A second thermoplastic layer  24  is formed having a rectangular cross-section to be mounted to a portion of the metal layer  22 . Of course, any suitable cross-section for the thermoplastic layers  24  is contemplated within the scope of the present invention. The thermoplastic layers  24  can be formed out of polycarbonate through injection molding or extrusion. The metal layer  22  is provided between the thermoplastic layers  24 . The metal layer  22  can be joined to the thermoplastic layers  24  in any suitable manner. In the illustrated embodiment, the metal layer  22  has an aperture  23  formed therein so that the first and second thermoplastic layers  24  can be joined directly together with the metal layer  22  provided therearound. The metal layer  22  may have a T-shaped cross-section. Of course, any suitable cross-section for the metal layer  22  is contemplated within the scope of the present invention. As illustrated, the metal layer  22  is a reinforcement, which may provide attachment points for other components. 
     In  FIG. 3 , another embodiment of a cross-section of reinforcement member  14  is depicted. The reinforcement member  14  has a first flange  26  that is mounted to the polycarbonate panel  12  at the attachment joint  32 . The first flange  26  is connected to an intermediate portion  28  that does not contact the polycarbonate panel  12 . The intermediate portion  28  is attached to a second flange  30  that is attached to the polycarbonate panel  12  at the attachment joint  32 . 
     The first flange  26  may be generally parallel with the polycarbonate panel  12  for ease of attachment. In at least one embodiment, the first flange  26  has a curvature corresponding with a curvature of the polycarbonate panel  12 . As illustrated, the first flange  26  has a thermoplastic layer  24  provided over a metal layer  22 . The metal layer  22  may have an aperture  23  provided therethrough. The aperture  23  may receive a pin therein to secure the thermoplastic layer  24  to the metal layer  22 . 
     The intermediate portion  28  extends from first flange  26  of the reinforcement member  14  to enhance stiffness of the polycarbonate panel  12 . In at least one embodiment, the intermediate portion  28  has a curved or angled cross-section. As illustrated, the intermediate portion  28  has a metal layer  22  without a corresponding thermoplastic layer  24 . 
     The second flange  30  is connected to the intermediate portion  28  and may be generally parallel with the polycarbonate panel  12  for ease of attachment. In at least one embodiment, the second flange  30  has a curvature corresponding with a curvature of the polycarbonate panel  12 . As illustrated, the second flange  28  has a thermoplastic layer  24  provided over a metal layer  22 . The metal layer  22  may have an aperture  23  provided therethrough. The aperture  23  may receive a pin therein to secure the thermoplastic layer  24  to the metal layer  22 . 
     With reference again to the embodiment of the invention applied to a roof module as illustrated in  FIG. 1 , receptacles  18  can be provided in the reinforcement member  14  that can be sized to receive vehicle components, including but not limited to the vehicle body and a sunroof sunshade roller. In at least one embodiment, the reinforcement member  14  is molded with metal attachment points  18  for sunshade rollers and/or other pertinent attachments. 
     Referring now to  FIG. 4 , another embodiment of the vehicle roof assembly  10  including the polycarbonate panel  12  with the reinforcement member  14  joined thereon. The reinforcement member  14 , as illustrated, is provided proximate two peripheral regions  16  to stiffen and support the polycarbonate panel  12 . 
     In at least one embodiment, the reinforcement member  14  is formed out of two or more separate pieces that are joined together. In one embodiment, the reinforcement member  14  has a uniform cross-section. In another embodiment, the reinforcement member  14  has multiple cross-sections that correspond with the two or more separate pieces that are joined together to form the reinforcement member  14 . 
     In  FIG. 5 , an embodiment of a cross-section of the reinforcement member  14  of  FIG. 4  is illustrated. The reinforcement member  14  has a cross-section to provide increased stiffness when attached to the polycarbonate panel  12 . The reinforcement member  14  has a first flange  26  that can be attached to the polycarbonate panel. The first flange  26  is connected to an intermediate portion  28 . The intermediate portion  28  is attached to a second flange  30  that can be attached to the polycarbonate panel  12 . The second flange  30  is attached to a second intermediate portion  28 . A third flange  40  is attached to the second intermediate portion  28 . Any amount of intermediate portions  28  and flanges may be provided to increase stiffness of the reinforcement member  14 . 
     Each of the first flange  26 , the second flange  30  and the third flange  40  may have a generally flat surface for ease of attachment to the polycarbonate panel  12 . Each of the first flange  26 , the second flange  30  and the third flange  40  may have a curvature corresponding with a curvature of the polycarbonate panel  12 . Each of the first flange  26 , the second flange  30  and the third flange  40  provide surfaces to join the reinforcement member  14  to the polycarbonate panel  12 . As discussed above, the reinforcement member  14  may be laser welded to the polycarbonate panel  12 . 
     As illustrated, the first flange  26 , the second flange  30  and the third flange  40  each have a thermoplastic layer  24  provided over a metal layer  22 . On the first flange  26  and the third flange  40 , the thermoplastic layer  24  surrounds the metal layer  22 . On the second flange  30 , the thermoplastic layer  24  is provided on one side of the metal layer  22 . The metal layer  22  may have an aperture  23  provided therethrough. The aperture  23  may receive a pin therein to secure the thermoplastic layer  24  to the metal layer  22 . 
     The first intermediate portion  28  extends from first flange  26  to the second flange  30  and the second intermediate portion  28  extends from the second flange  30  to the third flange  40 . The first intermediate portion  28  and the second intermediate portion  28  enhance stiffness when attached to the polycarbonate panel  12 . In at least one embodiment, each of the intermediate portions  28  have a curved cross-section. 
     One reinforcement member  14  formed with two or more pieces may have the cross-section depicted in  FIG. 3  for one of the two or more pieces and the cross-section depicted in  FIG. 5  for another of the two or more pieces of the reinforcement member  14 . Of course, the reinforcement member  14  may have any suitable cross-section corresponding to any suitable amount of pieces that are joined together to form the reinforcement member  14 . 
     As depicted in  FIG. 4 , the polycarbonate panel  12  can have contours  42  formed therein. In one embodiment, the contours  42  are ridges  42  that provide alignment while the reinforcement member  14  is laser welded to the polycarbonate panel  12 . In another embodiment, the contours  42  are provided to enhance aesthetics of the vehicle roof assembly  10 . In at least one embodiment, the contours  42  do not contact the reinforcement member  14  once the reinforcement member  14  is welded to the polycarbonate panel  12 . The contours  42  may be formed into the polycarbonate panel  12 , rather than extending beyond a surface of the polycarbonate panel  12 . Furthermore, the contours  42  may be formed on only a portion of the polycarbonate panel  12  and may have any desired shape and size. 
     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. Rather, 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.