Abstract:
A composite roof bow includes a flexible plastic segment and a rigid reinforcing segment. In another aspect of the present invention, the flexible plastic segment is insert molded to the reinforcing segment. In another aspect of the present invention, the flexible segment is predominately unfilled plastic and the reinforcing segment is filled plastic, which are attached together to create a generally rigid roof bow.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 09/383,801, filed on Aug. 26, 1999, now issued as U.S. Pat. No. 6,282,791. 
    
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
     This invention relates generally to roof bows and more particularly to a composite roof bow used with an automotive vehicle convertible roof. 
     It is well known to employ a plurality of roof bows for suspending a soft top convertible roof above a passenger compartment of an automotive vehicle. The roof bows are secured to the top by way of staple-like fasteners or placement of each bow within a pocket sewn to the lower side of the convertible roof. The soft top roof is commonly secured to the number one or forwardmost roof bow by being sandwiched between the number one bow and a trim panel. The roof bows are usually metal and extend in a cross-car manner between metal side rails which are oriented in a generally fore and aft manner. For example, a roof bow and side rail top stack mechanism are disclosed in U.S. Pat. No. 4,720,133 entitled “Convertible Top Structure” which issued to Alexander et al. on Jan. 19, 1988, the disclosure of which is incorporated by reference herein. Such traditional convertible roofs are movable from a raised and operable position covering the passenger compartment, to a stowed and retracted position in a bootwell between the passenger compartment and vehicle trunk. 
     Some conventional roof bow constructions have also attempted to combine metal with other assembled materials. For example, reference should be made to the following U.S. Pat. No. 5,560,670 entitled “Top Bow Tack Strip” which issued to Boardman on Oct. 1, 1996; U.S. Pat. No. 2,580,337 entitled “Folding Top Structure” which issued to Votypka on Dec. 25, 1951; U.S. Pat. No. 2,538,931 entitled “Bow and Tacking Strip Assembly” which issued to Zummach on Jan. 23, 1951; U.S. Pat. No. 1,789,137 entitled “Reinforced [sic] Wooden Bow and Method of Manufacture Thereof” which issued to Fitch on Jan. 13, 1931; and U.S. Pat. No. 366,511 entitled “Carriage Bow” which issued to Sampsell on Jul. 12, 1887. The wood roof bows are heavy, expensive to shape and are not dimensionally stable in wet weather. Moreover, for the versions employing unfilled plastic, the plastic bows appear to be relatively flexible and offer little freestanding structural support over the great distances spanned, especially when it is considered that the vehicle is often moving at high speeds on rough roads. 
     U.S. Pat. No. 5,427,429 entitled “Convertible Top Bow” which issued to Piontek et al. on Jun. 27, 1995, discloses a glass reinforced polymeric roof bow. Metal linkage hardware can be molded in place at the ends of the polymeric bow. While this patent is a significant improvement in the industry, it is desirable to further improve the characteristics of a rigid plastic roof bow by providing an additional metal insert in an area of the bow between the roof rail engaging ends. 
     In accordance with the present invention, a preferred embodiment of a composite roof bow includes a flexible plastic segment and a rigid reinforcing segment. In another aspect of the present invention, the flexible plastic segment is insert molded to the reinforcing segment. In another aspect of the present invention, the flexible segment is predominately unfilled plastic and the reinforcing segment is filled plastic, which are attached together to create a generally rigid roof bow. Still a further aspect of the present invention provides a metal reinforcing segment entirely disposed inside the plastic segment and the plastic segment has a generally I-cross sectional shape. In yet another aspect of the present invention, a reinforcement extends at least a majority of the cross-car length of the plastic bow. A method of making an automotive vehicle roof bow is also provided. 
     The composite roof bow of the present invention is advantageous over traditional bows in that the present invention advantageously uses the relatively lightweight and rigid property of a filled plastic while also minimizing brittle fracture of the plastic by employing either an unfilled plastic or a metallic reinforcement. The present invention is also advantageous by employing a low piece cost and fast method of manufacturing the composite bow with a minimal amount of manual assembly. The present invention achieves predictable tolerances regardless of environmental humidity while also employing relatively few parts to assemble the bow to a soft top convertible roof. Additional advantages and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partially exploded and sectioned perspective view showing a convertible roof employing the preferred embodiment composite roof bow of the present invention; 
     FIG. 2 is a fragmented perspective view showing the preferred embodiment composite roof bow; 
     FIG. 3 is a fragmented and exploded perspective view showing the preferred embodiment composite roof bow; 
     FIG. 4 is a cross sectional view, taken along line  4 — 4  of FIG. 2, showing the preferred embodiment composite roof bow; 
     FIG. 5 is a diagrammatic cross-sectional view showing an injection molding tool used to make the preferred embodiment composite roof bow of FIG. 4; 
     FIG. 6 is a fragmented perspective view showing a first alternate embodiment composite roof bow of the present invention; 
     FIG. 7 is a fragmented and exploded perspective view showing the first alternate embodiment composite roof bow; 
     FIG. 8 is a cross sectional view, taken along line  8 — 8  of FIG. 6, showing the first alternate embodiment composite roof bow; 
     FIG. 9 is a cross sectional view, similar to that of FIG. 4, showing a second alternate embodiment composite roof bow of the present invention; 
     FIG. 10 is a cross sectional view, similar to that of FIG. 4, showing a third alternate embodiment composite roof bow of the present invention; and 
     FIG. 11 is a cross sectional view, similar to that of FIG. 4, showing a fourth alternate embodiment composite roof bow of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates an automotive vehicle  21  having a body  23  and a convertible roof  25 . Convertible roof  25  is preferably of a soft top variety including a fabric roof  27 , a top stack mechanism  29  and a back window or backlite  31 . Top stack mechanism  29  employs a number one roof bow  35 , a number two roof bow  37 , a number three roof bow  39 , a number four roof bow  41  and a number five roof bow  43 . Roof bows  35 - 43  are coupled either directly or indirectly to generally fore-and-aft oriented side rails  45  or rear rail  47  on each side of vehicle  21 . Thus, the roof bows extend in a curved and generally horizontally oriented crosscar manner between the sets of rails when convertible roof  25  is disposed in its raised and operable position, as shown. When stowed or retracted, convertible roof  25  is lowered into a bootwell or other storage compartment in body  23 . 
     The preferred embodiment roof bow of the present invention is a two-part composite bow, such as exemplary number two bow  37 . However, it must be appreciated that any of the convertible top roof bows can be of the presently disclosed composite construction. Referring to FIGS. 2-4, the preferred embodiment composite roof bow  37  has an unreinforced plastic member  61  and a reinforced plastic member  63  extending throughout a middle segment  65  which is defined as the crosscar portion located between rail fastening ends  67 . Unreinforced plastic member  61  is preferably extruded from structurally unfilled nylon 6/6 while reinforced plastic member  63  is preferably injection molded from a 35-50% chopped glass fiber filled nylon 6/6. 
     Unreinforced plastic member  61  has a modified generally I cross sectional shape defined by an externally visible head  71  and a triangularly enlarged base  73 . Head  71  has a flat exterior surface  75  and opposed flat surfaces  77 . A pair of inwardly angled arms  79  of reinforced plastic member  63  securely grasp and at least partially encapsulate triangular base  73  therein. Arms  79  of reinforced plastic member  63  depend from the same face of a flat wall  81  (when viewed in cross section like FIG.  4 ). Rail fastening ends  67  are formed as part of reinforced plastic member  63  and may have a pivot hole or other rail attachment characteristics. Except for ends  67 , members  61  and  63  run in a parallel manner and have a generally uniform cross section. 
     An important characteristic of composite roof bow  37  is that reinforced plastic  63  provides significant tensile and compressive strength will also exhibiting dimensional stability in all environmental conditions. Furthermore, reinforced plastic member  63  is relatively lightweight thereby minimizing top stack actuation forces while enhancing vehicle fuel economy and engine performance. However, reinforced plastic member  63  is somewhat brittle. Therefore, unreinforced plastic member  61  reduces the overall brittleness of composite bow  37  since unreinforced plastic member  61  is a relatively resilient, flexible and fracture resistant component. More specifically, the resilient nature of unreinforced and structurally unfilled (pigment and regrind filling not being considered structural) material reduces brittleness and undesired failure of the composite bow while benefiting from the structural strength of reinforced plastic member  63 . Thus, both members  61  and  63  act together to synergistically enhance the overall composite bow characteristics by overcoming any inherent shortcomings of the other materials. Furthermore, head  71  of unreinforced plastic member  61  acts as a tack strip for receiving mechanical fasteners such as staples  91  (see FIG. 1) inserted therein in order to secure top  27  to roof bow  37 . 
     FIG. 5 illustrates an injection molding tool or mold having an upper movable die  93  and a lower die  95  operably associated with an injection molding machine (not shown). First, unreinforced plastic member  61  is extruded in an extrusion die associated with a plastic extrusion machine (not shown). The extrusion machine and extrusion die serve to provide a slight curve to unreinforced plastic member  61  and then member  61  is cut to the desired length. Second, unreinforced plastic member  61  is manually or robotically placed in lower die  95 . 
     Third, lower die  95  is shuttled into a usable position adjacent the injection molding nozzle. Upper die  93  is then closed against lower die  95  and the corresponding section of unreinforced plastic member  61 . Thus, unreinforced plastic member  61  is temporarily secured inside the tool while also defining part of the mold cavity  97  which creates the exterior shape of what will become reinforced plastic member  63  (see FIG.  3 ). 
     Fourth, the injection molding machine pushes and expels the molten glass filled plastic from the barrel, through the gate of the tool, through a runner system in the tool, and into cavity  97  of the tool. This causes the glass filled plastic to securely and permanently (without destruction) engage and at least partially encapsulate the base of unreinforced plastic member  61  in dies  93  and  95 . The reinforced plastic is allowed to cool, thereby solidifying and rigidifying within the tool. Fifth, upper die  93  is opened, lower die  95  is shuttled away from the injection molding machine and the joined members  61  and  63  are removed from the tool, thereby creating a composite roof bow. A non-shuttling, horizontally closing set of dies can also be used. It is alternately envisioned that one of the plastic members could be made of extruded or cast metal, such as aluminum, while the other of the plastic members is glass or otherwise structurally filled, but still using the same process as described with the preferred embodiment. 
     A first alternate embodiment is shown in FIGS. 6-8. This first alternate embodiment composite roof bow  101  employs a glass filled plastic member  103  having a middle segment  105  spanning between rail fastening ends  107 . Reinforced plastic member  103  has a uniform and generally rectangular cross sectional shape throughout middle segment  105 . Two or more crosscar-elongated metallic members  107  are locally insert molded partially within reinforced plastic member  103  at load intensive locations. These unreinforced or metal insert members  107  are spaced apart from each other, have a generally horizontal orientation (when in the raised position) and have a generally rectangular cross section. The leading and trailing edges  109  of each insert member  107  are tapered. Insert members  107  are stamped aluminum or steel which are partially encapsulated during the injection molding process. It is alternately envisioned that rectangular insert member  107  can continuously extend as a single elongated piece from middle segment  105  of reinforced plastic member  103 . Thus, insert member  107  provides ductility, resilience and fracture resistance while reinforced plastic member  103  is lightweight and structurally strong. 
     A second alternate embodiment of the present invention composite roof bow  121  is illustrated in FIG.  9 . In this embodiment, a circular cross-sectionally shaped metal member  123 , such as a rod or wire, is insert molded within a web  125  of an I cross sectionally shaped glass filled plastic member  127 . Web  125  spans in a perpendicular manner between a pair of parallel and opposed walls  129  thereby defining an I beam shape. Unreinforced metal member  123  continuously extends along the entire middle segment of composite bow  121 . 
     A third alternate embodiment is shown in FIG.  10 . This composite roof bow  141  employs a pair of spaced apart, parallel and continuous unreinforced or metal members  143  insert molded and entirely encapsulated within parallel walls  145  joined together by a web  147 . Walls  145  and web  147  are made of a glass reinforced plastic member  149  having a generally I cross sectional shape. Unreinforced insert members  143  are preferably extruded or stamped metal such as aluminum or steel but may alternately be unfilled (in other words, generally absent of a structural filler) plastic. 
     Finally, referring to FIG. 11, a fourth alternate embodiment composite roof bow  151  employs a continuous unreinforced or metal member  153  insert molded within a web  155  of a glass fiber reinforced plastic member  157 . Alternately, unreinforced member  153  may consist of multiple spaced apart insert members which are entirely encapsulated or predominantly encapsulated within the injection molded plastic. Plastic member  157  can also be extruded with metal member  153  therein. Various pins or other positioning members may be needed within the injection molding tool to properly locate the unreinforced insert member during injection molding of the reinforced plastic member. It is also envisioned that many of the internal and external corners shown may alternately be slightly rounded to ease flow of the plastic during molding and increase strength of the composite roof bow. 
     While various embodiments of the composite roof bow have been disclosed herein, other variations may be employed within the spirit of the present invention. For example, other shapes and locations of the reinforced and unreinforced component parts may be provided. Moreover, additional linkages may be needed to couple the roof bow ends to the rails or other top stack components. The composite roof bow of the present invention may also be used with a rigid hardtop roof. While various materials have been disclosed, other materials may alternately be employed as long as the disclosed function is achieved. It is intended by the following claims to cover these and any other departures from the disclosed embodiments which fall within the true spirit of this invention.