A storm door includes first and second horizontal rail portions each having a first end and a second end and having an internal steel reinforcement portion extending substantially from the first end to the second end, and first and second vertical rail portions each having a first end and a second end and having an internal steel reinforcement portion extending substantially from the first end to the second end. The first and second horizontal rail portions and the first and second vertical rail portions are coupled together to form a substantially rectangular frame of the storm door. The first and second horizontal rail portions and the first and second vertical rail portions comprise external PVC surfaces.

FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to storm doors and, more particularly, to a storm door having exterior PVC surfaces and a steel core.  
       BACKGROUND OF THE INVENTION  
       [0002]     Storm doors are used to provide an extra measure of thermal and moisture insulation at door openings of a building or home. A storm door can be located in the same door frame as a standard exterior door and positioned between the exterior door and the outside of the building or home to provide the thermal and moisture insulation.  
         [0003]     Storm doors typically come in a variety of different designs. For example, a full-view storm door includes a window that makes up the entire door except for the frame. The full-view storm door can be designed to permit the window to be exchanged with a screen. A self-storing storm door typically has three sections: a fixed window pane, a fixed solid pane formed of the same material as and integral with the frame of the door, and a combination window/screen pane that can be slidably interchanged so that the window and/or the screen is present in the pane. The combination window/screen pane is usually placed between fixed window pane and the fixed solid pane. Other storm doors, such as a crossbuck door, simply have a fixed solid pane and a single window pane that can be interchanged with a screen.  
         [0004]     In any design, it is desirable for the storm door to be strong and durable yet lightweight and inexpensive to manufacture. It would therefore be desirable to design a storm door that can satisfy these characteristics  
       SUMMARY OF THE INVENTION  
       [0005]     According to an aspect of the invention, a storm door includes first and second horizontal rail portions each having a first end and a second end and having an internal steel reinforcement portion extending substantially from the first end to the second end, and first and second vertical rail portions each having a first end and a second end and having an internal steel reinforcement portion extending substantially from the first end to the second end. The first and second horizontal rail portions and the first and second vertical rail portions are coupled together to form a substantially rectangular frame of the storm door. The first and second horizontal rail portions and the first and second vertical rail portions comprise external PVC surfaces.  
         [0006]     Further features, aspects and advantages of the present invention will become apparent from the detailed description of preferred embodiments that follows, when considered together with the accompanying figures of drawing. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is a front elevational view of a storm door consistent with the present invention.  
         [0008]      FIG. 2  is a sectional view taken along the lines A-A of  FIG. 1 .  
         [0009]      FIG. 3  is a sectional view taken along the lines B-B of  FIG. 1 .  
         [0010]      FIG. 4  is a sectional view taken along the lines C-C of  FIG. 1 .  
         [0011]      FIG. 5  is a detailed cutaway view taken at the corner D of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0012]     Referring now to  FIG. 1 , there is shown a front elevational view of a storm door consistent with the present invention. The storm door of  FIG. 1  is an example of a self-storing storm door. It should be understood, however, that the storm door can be designed differently, such as a full view storm door or a crossbuck door, and that the following description with respect to a self-storing storm door is for exemplary purposes only. As shown in  FIG. 1 , the storm door includes a pair of horizontal sashes or rails  1 , 2  and a pair of vertical sashes or rails  3 , 4 . The horizontal rail  1  is coupled at respective ends to a top end of the vertical sashes  3 , 4 , and the horizontal rail  2  is coupled at respective ends to a bottom end of the vertical sashes  3 , 4 . The combination of the horizontal rails  1 , 2  and the vertical sashes  3 , 4  forms a frame of the storm door of  FIG. 1 . The horizontal rails  1 , 2  and the vertical sashes  3 , 4  are preferably formed with PVC, although other materials may be used.  
         [0013]     The storm door of  FIG. 1  also includes a pair of sash muntins  5 , 6  that divide the storm door into three sections. The sash muntins  5 , 6  can be formed of PVC, aluminum, or some other lightweight material. A top section  7  preferably holds a window or glass pane. The window in top section  7  can be set in a fixed position. The middle section  8  preferably holds a window or glass pane and/or a screen. The window pane and screen may be slidable between the middle section  8  and the top section  7  so that either both or one is present in the middle section  8  at one time. It is also possible for the window pane and the screen to be respectively replaceable, i.e., one is popped or screwed into place at a time in the middle section  8 . A bottom section  9  preferably holds a fixed PVC panel, although the panel can be formed from other materials.  
         [0014]     The storm door of  FIG. 1  further includes a handle  10  for locking, opening, and closing the storm door. A plurality of hinges  11  are used to mount the storm door in a door frame of a home or building. Although the handle  10  is shown on the right side and the hinges  11  are shown on the left side of the storm door, it should be understood that the handle  10  and the hinges  11  can be reversed. In either position, the handle  10  and the hinges  11  are preferably positioned on the opposite sides of the storm door.  
         [0015]      FIG. 2  is a sectional view taken along the lines A-A of  FIG. 1 . The sectional view of  FIG. 2  shows details of the internal construction of the horizontal rails  1 , 2 . In particular, the horizontal rails  1 , 2  each include an internal steel reinforcement portion  12 . The internal steel reinforcement portion  12  is a relatively thin layer of steel and preferably has a substantially U-shaped or rectangular-shaped cross section. In addition, the internal steel reinforcement portion  12  preferably has a hollow core. The internal steel reinforcement portion  12  is formed to be in contact with or very nearly in contact with the exterior PVC portion of the horizontal rails  1 , 2 .  
         [0016]     In addition to the internal steel reinforcement portion  12 , each of the horizontal rails  1 , 2  includes a part of a corner reinforcement portion  13 . There is a part of the corner reinforcement portion  13  in each end of the horizontal rails  1 , 2 . The corner reinforcement portions  13  are preferably formed from PVC or other sturdy plastic material. The corner reinforcement portions  13  are preferably formed to have a substantially rectangular or square-shaped cross-section with a hollow core. The thickness of the corner reinforcement portions  13  is preferably greater than the thickness of the steel reinforcement portions  12 .  
         [0017]     The exterior PVC portion of the horizontal rails  1 , 2  is coupled to the steel reinforcement portions  12  and the corner reinforcement portions  13  by screws  14 . Although the coupling is shown as screws  14 , it should be understood that other coupling elements as are known in the art can be used to connect the exterior PVC portion of the horizontal rails  1 , 2  to the steel reinforcement portions  12  and the corner reinforcement portions  13 .  FIG. 2  also shows an internal support section  15 , which is preferably made of PVC or aluminum.  
         [0018]      FIG. 3  is a sectional view taken along the lines B-B of  FIG. 1 .  FIG. 4  is a sectional view taken along the lines C-C of  FIG. 1 . The sectional views of  FIGS. 3 and 4  show details of the internal design of the vertical rails  3 , 4 . In particular, like the horizontal rails  1 , 2 , the vertical rails  3 , 4  each include an internal steel reinforcement portion  12  preferably having the same thickness and design as that of the horizontal rails  1 , 2 . The vertical rails  3 , 4  also include a part of a corner reinforcement portion  13  positioned in each end of the vertical rails  3 , 4 . The exterior PVC portion of the vertical rails  3 , 4  is also coupled to the steel reinforcement portions  12  and the corner reinforcement portions  13  by screws  14 .  FIG. 3  also shows an internal support section  15 , which is preferably made of PVC or aluminum.  
         [0019]     In general, the internal steel reinforcement portions  12  provide stability to the storm doors. More specifically, the internal steel reinforcement portions and serve as a core  
         [0020]      FIG. 5  shows a detailed cutaway view of a corner portion of the storm door including a complete corner reinforcement portion  13 . The corner shown in  FIG. 5  is for the corner joining the horizontal rail  2  and the vertical rail  4 . It should be understood, however, that the view shown in  FIG. 5  is applicable to each of the other corners of the storm door.  
         [0021]     As shown in  FIG. 5 , a part of the corner reinforcement portion  13  is present in the horizontal rail  2 , and a part of the corner reinforcement portion  13  is present in the vertical rail  4 . As also shown in  FIG. 5 , the ends of the exterior PVC portions of the horizontal rail  2  and the vertical rail  4  are mitered at 45 degree angles such that, when the respective ends are joined together, the horizontal rail  2  and the vertical rail  4  form a 90 degree angle. The ends of the corner reinforcement portions  13  in the horizontal rail  2  and the vertical rail  4  are likewise formed in such a manner. As shown in  FIG. 5 , the corner reinforcement portions  13  extend only part way into the horizontal rail  2  and the vertical rail  4 . In an alternative embodiment, it is possible for the corner reinforcement portions  13  to extend the entire length or a greater portion of the horizontal rail  2  and the vertical rail  4 .  
         [0022]      FIG. 5  also shows that the internal steel reinforcement portions  12  extend substantially to the end of the horizontal rail  2  and the vertical rail  4 , but not as far as the corner reinforcement portions  13 . The internal steel reinforcement portions  12  preferably extend as close as possible to the end of the horizontal rail  2  and the vertical rail  4  to provide additional support for them. Two pairs of screws  14  are positioned adjacent to the corner of the storm door. The two pairs of screws  14  near each corner of the storm door can be the only elements coupling the exterior PVC portion of the horizontal rails  1 , 2  and vertical rails  3 , 4  to the respective steel reinforcement portions  12  and corner reinforcement portions  13 . Alternatively, additional screws  14  can be used for the coupling in each rail.  
         [0023]     The horizontal rail  2  and the vertical rail  4  are preferably coupled together at the respective exterior PVC portions and at the respective corner reinforcement portions  13 . The coupling can be made, for example, with a PVC weld. Alternatively, the rails can be coupled together with a metal bracket or other couplings as are known in the art.  
         [0024]     The foregoing description of preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light in the above teachings or may be acquired from practice of the invention. The embodiments (which can be practiced separately or in combination) were chosen and described in order to explain the principles of the invention and as practical application to enable one skilled in the art to make and use the invention in various embodiments and with various modifications suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.