Abstract:
A vehicle door comprising a strengthening structure, an inner door skin and a latch mechanism to be housed within the door, said mechanism having an engagement element that co-operates with the strengthening structure to allow the mechanism to be presented for rigid fixing within the door after the inner skin has been positioned relative to the strengthening structure; wherein at least one fixing element rigidly holds both the inner door skin and the latch mechanism to the strengthening structure.

Description:
This application claims priority to Great Britain patent application No. GB 0201215.1 filed on Jan. 21, 2002. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a vehicle door, and in particular to an apparatus and method for locating and fastening a door latch within such a door. 
     A typical vehicle door comprises an inner skin having an aperture and an outer skin. The aperture is provided to allow a door latch mechanism to be mounted directly onto a locally reinforced fixing area on the inner skin. A strengthening structure, such as side impact bar, may be fixed to the inner skin. The outer skin has little impact strength compared with the inner skin. During assembly of the door, the aperture allows the latch mechanism to be appropriately positioned within the door by an assembly worker or machine, prior to rigid fixing of the latch mechanism to the inner door skin, usually by three or so screws. 
     The impact strength of vehicle doors during both head on and side collisions is of paramount importance. While traditional doors with impact bars fixed to an inner door skin provide improved protection for vehicle passengers, their performance is limited by the strength of the inner door skin. A new type of vehicle door has been proposed, such as in PCT Application WO 01/23201 A1, where the strength of the door is principally provided by an inner structural member typically comprising a bar type frame with one or more cross members. Part of the frame may have a generally “U-shaped” cross section to provide runner means for mounting a retractable glass window. Such doors preferably have a thin continuous inner skin to provide a seal, but this is insufficiently strong or stiff to support the loads required for a latch mounting. Hence, in such doors it is necessary to attach the door latch directly to the structural member. 
     During assembly, it is necessary to position the latch mechanism, albeit non rigidly, such that when the inner door skin has been fixed to the structural member and outer door skin has been positioned ready for fixing to the structural member, the latch mechanism is maintained in a position which allows a fixing member to be inserted through holes in the outer door skin and strengthening structure and engage a thread in the lock mechanism, but equally allows the latch position to be controlled by the fixing member when it is tightened. This presents a problem as the latch mechanism cannot be held in position by an assembly worker or machine during assembly, unless the inner skin is fitted after the latch mechanism. This is disadvantageous as it requires extra fixing means and in particular as it is often necessary to verify the fixing torque of the latch after assembly of other components since this is a safety critical item. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an improved apparatus and method of fastening a latch mechanism in a vehicle door. Another object is to provide a latch mechanism for a vehicle door that has improved resistance to forced opening as a result of a vehicle collision. A further object is to provide an apparatus that assists the assembly of latches and like mechanisms to a vehicle door having an inner and outer door skin mounted on a strengthening structure. Another object of the invention is to provide a method of fixing door latch mechanisms to such doors. 
     According to one aspect, the invention comprises a vehicle door including a strengthening structure, an inner door skin and a latch mechanism to be housed within the door. The latch mechanism has an engagement member that cooperates with the strengthening structure to allow the latch mechanism to be presented for rigid fixing within the door after the inner skin has been positioned relative to the strengthening structure. A fixing member rigidly holds both the inner door skin and the latch mechanism to the strengthening structure. 
     According to another aspect, the invention comprises a latch mechanism, which is adapted to be fixed to both a door strengthening structure and to an inner door skin. The latch mechanism has an engagement member that cooperates with the strengthening structure to allow the latch mechanism to be presented for rigid fixing within a vehicle door after the inner skin has been positioned relative to the strengthening structure. A single fixing member rigidly holds both the latch mechanism and the inner door skin to the strengthening structure. 
     A further aspect the invention comprises a method of fixing a latch mechanism to a vehicle door. The method includes the steps of non rigidly attaching the latch mechanism, so that it is positioned for subsequent rigid fixing, to a strengthening structure using an engagement member fixed to the latch mechanism that cooperates with the strengthening structure. The method further includes the steps of positioning an inner door skin relative to the strengthening structure and rigidly fixing both the inner door skin and the latch mechanism to the strengthening structure by a fixing member. 
     These and other features of the present invention will be best understood from the following specification and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An embodiment of the invention will now be described by reference to the following diagrammatic illustrations in which: 
         FIG. 1  shows a section of part of a vehicle door in plain view; and 
         FIG. 2  shows a perspective view of a strengthening structure and a latch mechanism according to the invention where the latch mechanism includes a spigot; 
         FIG. 3  shows a perspective view of the strengthening structure and the latch mechanism where the latch mechanism includes a tongue; 
         FIG. 4  shows a perspective view of the strengthening structure and the latch mechanism where the latch mechanism includes a hook; 
         FIG. 5  shows a perspective view of the strengthening structure and the latch mechanism where the latch mechanism includes a flexible screw; 
         FIG. 6  shows a perspective view of the strengthening structure and the latch mechanism where the strengthening structure includes a spigot; 
         FIG. 7  shows a perspective view of the strengthening structure and the latch mechanism where the strengthening structure includes a tongue; 
         FIG. 8  shows a perspective view of the strengthening structure and the latch mechanism where the strengthening structure includes a hook; and 
         FIG. 9  shows a perspective view of the strengthening structure and the latch mechanism where the strengthening structure includes a flexible screw. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  schematically shows in plan view that part of a vehicle door  10  near a door latch mechanism  22 . The door  10  comprises a strengthening structure  12  housed within an outer door skin  16  and an inner door skin  18 . The strengthening structure  12  is generally elongate and tubular, of hollow cross section, and has a plate  14  attached to or formed at one end. The plate  14  may be attached to the strengthening structure  12  by various means, such as by welding or by screws (not shown). The plate  14  has a “V-shaped” notch  34 , provided to allow passage of a body mounted latch striker so that the latch mechanism  22  can function and engage the striker. In one example, the plate  14  has three holes  26  to allow rigid attachment of the latch mechanism  22  to the plate  14  of strengthening structure  12 . The latch mechanism  22  may take many forms, but will always be housed within the door  10  between the door skins near the rim portion  20  of inner door skin  18  which is, in this case, a rear edge of a side opening door hinged at its front edge. The rim portion  20  also has three holes (not shown) configured to align with holes  26  in the plate  14  when the latch mechanism  22  is rigidly fixed to the door. 
     The latch mechanism  22  has an engagement member, such as a protrusion  28 , that co-operates with a fixing hole  32  in strengthening structure  12  to allow fixing of the latch mechanism  22  (see below). In the present embodiment, the protrusion  28  takes the form of a flexible spigot  28   a  with deformable teeth  30 , is made of plastics material and is attached to the latch mechanism  22  by conventional means. This is a preferable feature that allows sufficient flexibility or toleranced play in the fit between the three fixing members  24  and the holes  26 , insuring that the fixing members  24  cause the latch mechanism  22  to be positioned correctly relative to the strengthening structure  12 , and optionally in conjunction with other elements such as a tongue and slot or hook (not shown). The fixing members  24  of the present embodiment are threaded fasteners in the form of screws. 
     Thus, during assembly of the door, the outer door skin  16  is attached to the strengthening structure  12 , the latch mechanism  22  is non-rigidly attached to the strengthening structure by the protrusion  28  (a spigot  28   a ) and the inner door skin  18  is then positioned against the inside of the strengthening structure  12  for fixing. The inner door skin  18  is fixed in part to the strengthening structure  12  by the three fixing members  24  that pass through the holes in the rim portion  20  of the inner door skin  18 , through the holes  26  in the plate  14  and thereby into threaded bores in the latch mechanism  22  (not shown). On tightening the fixing members  24 , the latch mechanism  22  is rigidly fixed to the strengthening structure  12  in the correct position relative to the rear of the door  10 . 
     The door  10  will also typically have a glass window  36  retractably mounted on guide channels  38  (only one shown). The guide channels  38  may be formed as part of a frame strengthening structure, for example using a frame strengthening structure with a “U-shaped” cross section. 
     The strengthening structure may take a variety of forms. For example, it may comprise a frame located between the inner door skin  18  and outer door skin  16  near the edge of the door  10 . It may comprise such a frame with one or more side impact bars. The cross section of the frame members/bars can be other shapes besides tubular, for example “L” or “U” shaped. In another aspect, the plate  14  may be formed as an integral part of strengthening structure  12  and/or the strengthening structure  12  may itself be formed by joining more than one elongated component. 
     The protrusion  28  may be formed or attached to either the latch mechanism  22  or the strengthening structure  12 . The protrusion  28  may also take the form of a tongue  28   b  (shown in FIG.  3 ), or a hook  28   c  (shown in FIG  4 ), or a flexable screw (shown in FIG.  5 ). The protrusion  28  described above as generally cylindrical shaped spigot is described by way of example only. The protrusion  28  can have various cross sectional shapes and may be tubular or non tubular in form. The deformable teeth  30  may also be replaced by other fixing means, such as deformable prongs that engage the inside rim of the fixing hole  32 . If the protrusion  28  is located on the strengthening structure  12 , the protrusion  28  can be a spigot  28   a,  a tongue  28   b,  a hook  28   c,  or a flexible screw  28   d  as shown in  FIGS. 6 ,  7 ,  8  and  9  respectively. 
     Alternatively, but less preferably, the latch mechanism  22  may be non-rigidly held in place to the strengthening structure  12  by a clipping arrangement between the latch mechanism  22  and the strengthening structure. Such an arrangement does not require a slot, aperture or a recess that cooperate with the protrusion  28 . 
     The invention conveniently allows a latch mechanism  22  to be loosely and temporarily held in position ready for rigid fixing at the time of fixing the inner door skin  18 . The door  10  of the invention has enhanced resistance to forced opening of the lock during a collision as the latch mechanism  22  is directly fixed to a strengthening structure  12  designed to resist impact, especially side impact. It is important to prevent doors opening during a collision as the structure is significantly more rigid if the door  10  remains in place and is therefore able to stiffen the side structure of the vehicle  10 . 
     The foregoing description is only exemplary of the principles of the invention. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, so that one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.