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 engagement means that co-operate 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 means rigidly holds both the inner door skin and the latch mechanism to the strengthening structure.

Description:
[0001]    This application claims priority to Great Britain patent application No. GB 0201215.1 filed on Jan. 21, 2002. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    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.  
           [0003]    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 too 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.  
           [0004]    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.  
           [0005]    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 have 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  
         [0006]    An object of the present invention is to provide improved door latch mounting means for vehicle doors. Another object is to provide a latch system 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 latches to such doors.  
           [0007]    According to one aspect the invention comprises a vehicle door comprising a strengthening structure, an inner door skin and a latch mechanism to be housed within the door, said mechanism having engagement means that co-operate 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 means rigidly holds both the inner door skin and the latch mechanism to the strengthening structure.  
           [0008]    According to another aspect the invention comprises a latch mechanism, adapted to be fixed to both a door strengthening structure and an inner door skin, having engagement means that co-operate with a strengthening structure to allow the mechanism to be presented for rigid fixing within a vehicle door after the inner skin has been positioned relative to the strengthening structure; and wherein a single fixing means may rigidly hold both the latch mechanism and an inner door skin to a strengthening structure.  
           [0009]    In a further aspect the invention comprises a method of fixing a latch mechanism to a vehicle door comprising the steps of:  
           [0010]    a. non rigidly attaching a latch mechanism, so that it is positioned for subsequent rigid fixing, to a strengthening structure using engagement means fixed to the latch mechanism that co-operate with the strengthening structure;  
           [0011]    b. positioning an inner door skin relative to the strengthening structure; and  
           [0012]    c. rigidly fixing both the inner door skin and the latch mechanism to the strengthening structure by at least one fixing means. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    An embodiment of the invention will now be described by reference to the following diagrammatic illustrations in which:  
         [0014]    [0014]FIG. 1 shows a section of part of a vehicle door in plan view, and  
         [0015]    [0015]FIG. 2 shows a perspective view of a strengthening structure and a latch mechanism according to the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]    [0016]FIG. 1 schematically shows in plan view that part of a vehicle door  10  near to the door latch mechanism  22 . The door 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. Plate  14  may be attached to the strengthening structure  12  by various means, such as by welding or by screws (not shown). Plate  14  has—a “V-shaped” notch  34 , provided to allow passage of a body mounted latch striker so that a latch mechanism  22  can function and engage the striker. Plate  14  has three holes  26  to allow rigid attachment of the latch mechanism  22  to plate  14  of strengthening structure  12 . Latch mechanism  22  may take many forms but will always be housed within the door between the door skins near the rim portion  20  of inner door skin  18 , in this case a rear edge of a side opening door hinged at its front edge. The rim of door skin  20  also has three holes (not shown) configured to align with holes  26  in plate  14  when latch mechanism  22  is rigidly fixed to the door.  
         [0017]    Latch mechanism  22  has an engagement means comprising a protrusion  28  that cooperates with a hole  32  in strengthening structure  12  to allow fixing of the latch (see below). In the present embodiment protrusion  28  takes the form of a flexible spigot with deformable teeth  30 , made of plastics material and attached to the latch mechanism by conventional means: This is a preferable feature that allows sufficient flexibility or toleranced play in the fit between three fixing means  24  and holes  26  etc., to insure that the fixing means  24  when fitted cause the latch to be positioned correctly relative to the strengthening structure  12 , optionally in conjunction with other elements such as a tongue and slot or hook (not shown). The fixing means of the present embodiment are threaded fasteners in the form of screws.  
         [0018]    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  12  by means of engagement means  28  (spigot) and then the inner door skin  22  is positioned against the inside of the strengthening structure  12  for fixing. The inner skin  18  is fixed in part to the strengthening structure  12  by three screws  24  that pass through the holes in the rim  20  of the inner skin, through the holes  26  in plate  14  and thereby into threaded bores in the latch mechanism (not shown). On tightening screws  24  latch mechanism  22  is rigidly fixed to strengthening structure  12  in the correct position relative to the rest of the door.  
         [0019]    The door will also typically have a glass window  36  retractably mounted on guide channels  38  (only one shown). Guide channels  38  may be formed part of a frame strengthening structure, for example using a frame with a “U-shaped” cross section.  
         [0020]    The strengthening structure may take a variety of forms, for example it may comprise a frame located between the inner and outer door skin near the edge of the door. It may comprise such a frame with one or more side impact bars. The cross section of the frame members/bars can be other than tubular, for example “L” or “U” shaped. In another aspect, plate  14  may be formed as an integral part of strengthening structure  12  and/or strengthening structure  12  may itself be formed by joining more than one elongated component.  
         [0021]    The protrusion  28  may be formed or attached to either the latch mechanism or the strengthening structure. The protrusion may take the form of a tongue or a hook. The generally cylindrically shaped spigot  28  is described above by way of example only. The spigot can have various cross section shapes and may be tubular or non tubular in form. The deformable teeth  30  may be replaced by other fixing means such as deformable prongs that engage the inside rim of fixing hole  32 .  
         [0022]    Alternatively, but less preferably, the latch mechanism may be non-rigidly held in place to the strengthening structure by a clipping arrangement between the latch mechanism and the strengthening structure, such an arrangement not requiring a slot, aperture or a recess that cooperate with a protrusion.  
         [0023]    The invention conveniently allows a latch mechanism to be loosely and temporarily held in position ready for rigid fixing at the time of fixing the inner door skin. The door of the invention has enhanced resistance to forced opening of the lock during a collision as the lock mechanism is directly fixed to a strengthening structure 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 remains in place and is therefore able to stiffen the side structure of the vehicle.  
         [0024]    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.