Abstract:
A plastic window for use in a motor vehicle includes a plastic panel having portions defining an edge about a perimeter of the panel and a window flange integral to the plastic panel. The window flange is positioned adjacent to the edge and extends at least partially them along. The window flange includes an engagement feature configured to engage a corresponding engagement feature of a window frame. A window assembly Includes the plastic window and a window frame configured to be attached to a motor vehicle. The window frame has portions forming the corresponding engagement feature which receive the engagement feature of the window flange to secure the plastic window to the window frame. A method of installing a window on a motor vehicle is also disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Application Ser. No. 60/862,281 filed on Oct. 20, 2006, entitled “POLYCARBONATE GLAZING FOR MODULAR DOORS,” the entire contents of which are incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention generally relates to windows for motor vehicles, and more particularly, to plastic windows for motor vehicles. 
   2. Description of the Related Technology 
   Over the past several decades, automobile manufacturers have sought to improve automobiles in every way. From improving safety, to enhancing functionality, to lowering costs, they have made great strides. One area of great concern, especially recently, is the rising cost of gasoline. In the past few years alone, gasoline has reached record high prices in the United States. One way the industry is trying to combat the problem is by developing alternative fuel technologies. However, developing alternative fuel technologies involves barriers to entry, such as lack of infrastructure and available fuel sources. Another way the industry is addressing the problem of high gas prices is by attempting to introduce gasoline powered automobiles that are more fuel efficient. This has been accomplished to some extent by introducing more efficient drive trains, but there are limitations to this approach due to vehicle weight. Thus, attempts have been made to reduce vehicle weight. In the past, however it was generally believed that reducing the weight of a vehicle exterior compromised the safety of the vehicle. 
   Windows in automobiles have typically been constructed of glass. Automotive glass has many limitations due to inherencies with the material. More specifically, automotive glass is constrained by the need to include complex attachment and regulating systems that add considerable weight to a door module, which is in addition to the weight of the glass itself. This additional weight impacts the performance of a car or truck by increasing fuel consumption and/or raising the center of gravity of the vehicle. Therefore, a need exists in providing a weight reduction in automotive glass and door modules. 
   Glass and other window systems may further be undesirable due to their complexity in assembling the window systems. For example, glass systems commonly utilize primer and bonding materials to attach the glass to the window frame. Glass may also be undesirable because of its propensity to shatter, and because it may need to be shattered in an emergency situation to create an escape route. 
   SUMMARY 
   The present invention provides a window for a motor vehicle, a window assembly for a motor vehicle, and a method of installing a window on a motor vehicle, which add little complexity and extra weight to a motor vehicle. Further, the present invention improves the safety of a motor vehicle, rather than compromising the safety of the vehicle. 
   In one aspect, a plastic window for use in a motor vehicle comprises a plastic panel having an edge and a window flange. The window flange is positioned adjacent to the edge and is configured to engage a corresponding feature of a window frame. 
   In another aspect, a window assembly for use in a motor vehicle comprises a plastic window and a window frame. The plastic window has an edge and a window flange positioned adjacent to the edge, the window flange having a lip. The window frame is configured to be attached to a motor vehicle. The window frame has portions forming a corresponding engagement feature, wherein the engagement feature of the window flange is matingly received within the corresponding engagement feature to secure the plastic window to the window frame. 
   In yet another aspect, a method of installing a window on a motor vehicle is provided. The method includes the steps of providing a plastic window having an edge and a window flange positioned adjacent to the edge and providing a window frame having portions forming a locking groove extending from an exterior surface of the motor vehicle. The method also includes a step of applying a force to the plastic window to snap the window flange into the locking groove to secure the plastic window to the window frame. 
   These and other aspects and advantages of the present invention will become apparent upon reading the following detailed description of the invention in combination with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a plastic window embodying the principles of the present invention; 
       FIG. 2  is a close-up perspective of a window flange of the plastic window of  FIG. 1 , embodying the principles of the present invention; 
       FIG. 3  is a cross-sectional view of the plastic window of  FIG. 1  and a window frame embodying the principles of the present invention; 
       FIG. 4  is a cross-sectional view of the plastic window and window frame of  FIG. 3  in an assembled form, thus illustrating a window assembly embodying the principles of the present invention; 
       FIG. 5  is a perspective view of the window assembly of  FIG. 4 , embodying the principles of the present invention; 
       FIG. 6  is a cross-sectional view of the plastic window and window frame of  FIGS. 3-5 , embodying the principles of the present invention, illustrating a removal feature of the assembly; and 
       FIG. 7  is a block diagram illustrating a method embodying the principles of the present invention. 
   

   DETAILED DESCRIPTION 
   Referring now to  FIGS. 1 and 2 , a plastic window for use in a motor vehicle is illustrated and designated generally at  10 . The plastic window  10  is shown embodying a generally rectangular shape having four edges  12 , however, it should be understood that the plastic window  10  could have any other desired shape, without falling beyond the spirit and scope of the present invention. By way of example, the plastic window  10  could be of a triangular shape having three edges  12 , or of an ovular shape having one continuous edge  12 . 
   The plastic window  10  has a plastic panel  16  and a window flange  18  positioned adjacent to the edges  12  of the plastic window  10 . The plastic panel  16  and the window flange  18  are preferably a unitary structure molded as one piece, in either a one-shot or two-shot process. However, they could alternatively be formed separately and attached together, for example, with glue, adhesives, or heat setting. The window flange  18  is shown as being continuous around each edge  12  of the plastic window  10 , however, it should be understood that the window flange  18  could alternatively be comprised of a series of discrete, separate flanges. In some designs, it may be desirable to avoid having the window flange  18  extend around the corners  19  of the plastic window  10 . 
   Preferably, the plastic panel  16  and window flange  18  are made of polycarbonate, which has a high impact strength and excellent transparency. Alternative suitable materials may include, by way of example, polymethylmethacrylate (PMMA), acrylic, polyacrylate, polyester, polysulfone, or copolymers, and combinations thereof. It is also contemplated that the plastic panel  16  and/or the window flange  18  could be formed of other thermoplastic resins, or any other suitable material. The plastic panel  16  and the window flange  18  may include bisphenol-A polycarbonate and other polycarbonate resin grades (such as branched or substituted) as well as being copolymerized or blended with other polymers, thereby, forming a blend with Acrylonitrile Butadiene Styrene (PC/ABS blend), or a polyester (PC/POLYESTER blend). In the alternative, the window flange  18  could be formed of any other material that may be attached to the plastic panel  16 , such as metal. The plastic panel  16  is most preferably transparent, or less preferably translucent, however, the window flange  18  may be opaque, translucent, or transparent as a particular application warrants. The plastic panel  16  and window flange  18  may further comprise various additives, such as colorants, mold release agents, antioxidants, and ultraviolet absorbers. 
   The plastic window  10  may also have protective or functional layers located on the plastic panel  16 . The protective or functional layers may include one or more of a weathering layer, a conductive layer, a decorative layer, and an abrasion resistant layer. These layers may be included on either or both sides of the plastic panel  16 , and more than one of the same type of layer could be included on the same side of the plastic panel  16 . For example, there could be multiple weathering layers for enhanced protection. 
   The weathering layer may provide weatherability to the plastic window  10 , including protection from the sun&#39;s rays and other elements. By way of example, the weathering layer may be a film comprising polycarbonate, PMMA, a combination of polycarbonate and PMMA, polysiloxane, polyurethane, polyurethane acrylate, or any other suitable material. Further, the weathering layer may include a coating of a material such as acrylic, polyurethane, siloxane, or a combination of these types of materials to provide a high weatherability, including long term ultraviolet (UV) protection. Further, silicone nano-particles may be blended into the weathering layer or a siloxane co-polymer may be formed into the material making up the weathering layer by polymerization, which may help promote adhesion between the weathering layer and adjacent layers. The weathering layer may also include UV absorbing molecules, such as by way of example, one or more of or a combination of inorganic oxides, benzophenones, benzoylresorcinols, cyanoacrylates, triazines, oxanilides, and benzotriazoles. Preferably, the weathering layer has a thickness between 10 and 1250 micrometers. The weathering layer may be as described in U.S. Pat. No. 6,797,384, which is hereby incorporated by reference in its entirety. 
   The conductive layer could be provided as a resistive layer or grid, to serve as a heater, defroster, defogger, or an antenna, by way of example. The conductive layer could comprise, for example, a printed resistive ink or a transparent conductive layer applied to the plastic panel  10  or one of the other layers. 
   The decorative layer could add any desired decoration to the plastic window  10 . For example, the decorative layer could form an image or define a blackened border to hide molding defects or a decorative printed ink. 
   The abrasion resistant layer may include a single layer or multiple sub-layers. The abrasion resistant layer may be comprised of aluminum oxide, barium fluoride, boron nitride, hafnium oxide, lanthanum fluoride, magnesium fluoride, magnesium oxide, scandium oxide, silicon monoxide, silicon dioxide, silicon nitride, silicon oxy-nitride, silicon oxy-carbide, hydrogenated silicon oxy-carbide, silicon carbide, tantalum oxide, titanium oxide, tin oxide, indium tin oxide, yttrium oxide, zinc oxide, zinc selenide, zinc sulfide, zirconium oxide, zirconium titanate, or a mixture or blend thereof. Preferably, the abrasion resistant layer is comprised of a composition of SiO x  or SiO x C y Hz depending upon the amount of carbon and hydrogen atoms that remain in the deposited layer. In this regard, the abrasion resistant layer resembles a “glass-like” coating. The abrasion resistant layer may also comprise UV absorbing molecules, such as, but not limited to, inorganic oxides, benzophenones, benzoylresorcinols, cyanoacrylates, triazines, oxanilides, and benzotriazoles. 
   The various layers may be applied by any technique known to those skilled in the art. Such techniques include, by way of illustration and not limitation, coating techniques (sol-gel, spray, flow, dip and curtain), film insert molding techniques, printing techniques (screen printing, membrane image transfer, pad printing) and deposition techniques (plasma-enhanced chemical vapor deposition (PECVD), expanding thermal plasma PECVD, plasma polymerization, photochemical vapor deposition, ion beam deposition, ion plating deposition, cathodic arc deposition, sputtering, evaporation, hollow-cathode activated deposition, magnetron activated deposition, activated reactive evaporation and thermal chemical vapor deposition). 
   To provide the plastic window  10  with additional stiffness, the plastic window  10  may have a reinforcing frame  20  positioned about and along the edges  12  of the plastic window  10 . Such a reinforcing frame  20  may include an outer portion  22  (located between the window flange  18  and the plurality of edges  12 ) and an inner portion  24  (located between a center C of the plastic panel  16  and the window flange  18 ). It should be understood that the reinforcing frame  20  is optional, and it could alternatively be provided having merely one of the outer and inner portions  22 ,  24 . Such a reinforcing frame  20  is preferably formed of metal, although any other suitable material could be used. Further, the reinforcing frame  20  could be attached by any suitable method, for example, by using glue or adhesives. 
   Referring to  FIGS. 3 and 4 , the plastic window  10  is shown in an uninstalled positioned adjacent to a window frame  30  in  FIG. 3  and in an installed position in  FIG. 4 . The window flange  18  extends outward from an interior surface of the panel  16 , adjacent to the panel&#39;s edge  12  and generally defines a rim-like structure about the panel  16 . The distal end of the flange  18  defines an engagement feature and is shaped so as to matingly engage a corresponding locking groove  34  formed as part of the window frame  30 . For this purpose, the distal end is tapered with a ramp surface  21  that assists with the entry of the flange  18  into the groove  34 . The ramp surface  21  terminates in a catch or lip  26  configured to engage a corresponding feature in the window frame  30 . While described with particularity, it should be understood that the window flange  18  could have other configurations configured to engage the locking groove  34 , without falling beyond the spirit and scope of the present invention. 
   The window frame  30  generally corresponds to the shape of the plastic window  10  and is fixed to and extends from an exterior surface  32 , such as a sheet metal exterior, of a motor vehicle and has portions forming the locking groove  34 . The locking groove  34  may be stamped or otherwise formed into the window frame  30 . To retain the window  10 , the window frame  30  includes a hem flange  36  defining a catch portion of the locking groove  34 , which interacts with and engages the lip  26  of the flange  18 . The hem flange  36  is shaped to matingly engage the lip  26  of the window flange  18  when inserted into the locking groove  34 . 
   A release handle  38 , or pull tab, is shown as being coupled to the hem flange  36 . The release handle  38  may extend from an attachment portion  39  that is secured, for example by welding, to the underside of the vehicle exterior surface  32  or the window frame  30  itself. The release handle  38  may be welded or otherwise coupled to the hem flange  36  such that when a user applies a predetermined force to the release handle  38 , the hem flange  36  is moved away from the lip  26  of the window flange  18 . This procedure is described in further detail below. 
   In the installed position, (see  FIG. 5 ) the plastic window  10  is flush mounted with the exterior surface  32  of the vehicle. Thus, the locking groove  34  is provided at a predetermined distance from the exterior surface  32  of the vehicle, so that when the plastic window  10  is installed, it will be mounted approximately flush with the exterior surface  32  of the vehicle. 
   Rubber seals  28  extend around the edges  12 , to seal the edges of the plastic window  10  when it is installed onto a motor vehicle. The rubber seals  28  may help accommodate thermal expansion and may assist with noise reduction. Further, the rubber seals  28  may function as weather stripping to block out wind, rain, and other elements, for example. 
   With reference to  FIG. 6 , the plastic window  10  is shown immediately after removal from the window frame  30 . When a user applies a predetermined force F to the release handle  38 , the hem flange  36  is pulled away from at least a portion of the window flange  18  and a user can then push the plastic window  10  away from the window frame  30 . To aid in this movement of the release handle  38  and hem flange  34 , a weakening strip  37  may be formed into the release handle  38  as a notched or scored groove. Preferably, the weakening strip  37  is located next to the locking groove  34  so as to allow for movement of the hem flange  36 . This releases the plastic window  10  from the window frame  30 . As such, the release handle  38  can be used as an emergency escape mechanism. Further, the release handle  38  could also allow for release of the plastic window  10  for routine cleaning, maintenance, or replacement. 
   In addition to the release handle  38 , or as an alternative, the hem flange  36  could be designed to withstand the application of outward forces up to a certain limit. Thus, the window assembly  40  could be designed to allow a user to apply a predetermined force to the plastic window  10 , such as a kicking force from the interior of the vehicle, to push the plastic window  10  out of the window frame  30 , if desired. 
   With reference to  FIG. 7 , as evident from the above discussion, the plastic window  10  may be installed using a method  60  that does not require glue or adhesives. The method  60  referring to  FIG. 7  includes the step  62  of providing a plastic window  10  having an edge  12  and a window flange  18  positioned adjacent to the edge  12 . The method  60  also includes providing a window frame  30  having portions forming a locking groove  34  extending from an exterior surface  32  of the motor vehicle (step  64 ), and (step  66 ) securing the plastic window  10  to the window frame  30  by applying a force to the plastic window  10  to snap the window flange  18  into the locking groove  34  of the frame  30 . 
   The method  60  may optionally include providing the portions forming the locking groove  34  at a predetermined distance from the exterior surface  32  of the motor vehicle such that the plastic window  10  is flush mounted with the exterior surface  32  of the motor vehicle once the window flange  18  has been snapped into the locking groove  34 . Another optional step of the method  60  may include releasing the plastic panel  16  from the window frame  30  by pulling on a release handle  38  being configured to pull the hem flange  36  away from the window flange  18 , thereby releasing the window flange  18  from the locking groove  34 . 
   Thus, the present invention provides a window assembly  40  wherein the plastic window  10  may be attached to the window frame  30  in a single step by pressing or snapping the window flange  18  of the plastic window  10  into the locking groove  34  of the window frame  30 . This type of assembly may be described as a snap-fit, press-fit, or zip-locked window assembly  40 . The plastic window  10  can achieve this mounting method because it is much easier to handle than glass, as well as weighing about 50% less than a glass window. 
   The window frame  30  has been illustrated and described as being fixed to the exterior surface  32  of the motor vehicle. Thus, the previously described embodiment of the invention provides a fixed window assembly  40 . In an alternate embodiment, however, the window frame  30  could be a movable frame such that the plastic window  10  could be moved to open and close the plastic window  10 , as is common in sun roofs and windows on the driver&#39;s and passenger&#39;s sides of a motor vehicle. 
   As a person skilled in the art will readily appreciate, the above description is meant only as illustrative implementation of the principles this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from the spirit of this invention.