Patent Publication Number: US-6988750-B2

Title: Door latch and door latch installation method

Description:
This application claims priority from United Kingdom (GB) Patent Application No. 0126790.5 filed on 8 Nov. 2001. 
   The present invention relates to a door latch and to a method of installing a door latch. More particularly, the present invention relates to a door latch for a vehicle door and a method of installing a door latch in a vehicle door. 
   It is becoming increasingly prevalent to fit a number of door components such as latches, window regulators, and speakers to a door subassembly commonly known as a door module. This enables the subassembly to be assembled away from the vehicle assembly line, and can therefore minimize the overall assembly time of a vehicle by enabling the module to be fitted to the door as a single item on the assembly line. 
   Doors are generally assembled from the outside face in. This means that the door outside release handle and key barrel must normally be fitted to the outer door skin prior to the fitting of the door module. Additionally, once the door module is fitted, it is difficult to access the void between the door module and the door outer skin to manually connect the inside release handle and key barrel to their respective linkages that transmit inputs therefrom to the latch. Furthermore, it is undesirable to attempt to connect these linkages whilst installing the door module since the process can be fiddly and the overall assembly time is therefore increased. The linkages may also foul on other door fittings during fitment of the door module if left unrestrained. 
   The present invention seeks to overcome, or at least mitigate, the aforesaid problems. 
   SUMMARY OF THE INVENTION 
   One aspect of the present invention provides a door latch for a vehicle door comprising a first lever for the transmission of a first input to the latch from first input means and a second lever for the transmission of a second input to the latch from second input means, wherein the first lever is capable of retaining the second lever in a retracted position when the first lever is in a rest position, but when the first lever is in an actuated position, enables the second lever to move to a deployed position at which the second lever may transmit the second input from the second input means. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: 
       FIG. 1  is a perspective view of a portion of a door including a latch according to the present invention, showing a lever of the latch in a first position; 
       FIG. 2  is a perspective view of the latch of  FIG. 1  showing the lever in a second position; 
       FIG. 3  is an enlarged perspective view of the portion F circled in  FIG. 2 ; 
       FIG. 4  is a cross section along the axis X—X of  FIG. 3 ; and 
       FIGS. 5A and 5B  are cross-sectional views of the key barrel of  FIG. 4  in first and second positions viewed along the axis Y—Y of  FIG. 4 . 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
   Referring to  FIG. 1 , there is shown a portion of a door  8  in which, for clarity, the majority of the door skin is not shown. A door module  10  is secured to the door by fasteners such as screws (not shown), for example. The module  10  comprises in this embodiment, a latch  12  and an intermediate panel  14  to which the latch is secured by a bracket  16 . 
   The latch  12  is provided with a key lever  18  on latch housing  13 , which when installed in the door is arranged to transmit inputs from key barrel  36  via key barrel output arm  38  and coupling  40  as described in greater detail below. A guide means in the form of a pair of parallel spaced guide bars  15 , between which the key lever  18  is arranged, is preferably provided on the latch  12  to ensure that the key lever  18  deploys along the correct path as described below. The latch  12  further comprises an outside handle release lever or paddle  26  pivotally mounted at pivot  27  to the latch housing  13  and provided with an inclined ramp surface  28  arranged to be engaged by a finger  30  of an outside release handle linkage  32  from an outside release handle illustrated schematically at  33 . 
   Considering the key lever in more detail, it can be seen that in  FIG. 1  the key lever  18  is restrained in a retracted position due to lug  24  (of key lever  18 ) engaging with a projection  44  provided on outside release lever  26 . The projection  44  is obscured in  FIG. 1  but is visible in  FIG. 2 . Key lever  18  is rotatably mounted to the latch about pivot  20  and is resiliently biased in a clockwise direction (B) by suitable means such as a torsion spring (not shown). However, the movement of key lever  18  to lock and unlock the latch is substantially vertical. 
   In order to engage the key barrel, a suitable formation is provided at the free end of the key lever  18 . This can be seen most clearly in  FIGS. 3 and 4 , and this embodiment comprises three guide teeth  22  having appropriate mutual spacing to receive the coupling  40 . To accommodate any tolerance errors in the positioning of the key lever  18  relative to the key barrel  36 , the ends of each tooth  22  are preferably bevelled to guide the key lever  18  into engagement with the coupling  40 . To provide positive engagement between the key lever  18  and the coupling  40 , a projection  25  is preferably provided on the key lever  18  to engage in a central aperture  42  provided in the coupling  40 . 
   During assembly (with the outside release handle linkage  32  and the key barrel  36 , key barrel output arm  38  and coupling  40  in place), a door assembler offers the door module  10  up to the door  8  and secures the two assemblies together using suitable fasteners such as screws. During this installation, the key lever  18  is held in the restrained position shown in  FIG. 1  behind projection  44 . In this position, the risk of key lever  18  fouling on one of the door components is reduced. The installation process also causes the ramp surface  28  of release lever  26  to be positioned outside of finger  30 . 
   To release the key lever  18 , the door assembler pulls on the door outside release handle (not shown) that has previously been installed on the door outer skin  34  in a direction indicated by arrow A. This in turn causes finger  30  of linkage  32  to ride along ramp surface  28  and cause release lever  26  to pivot in a clockwise direction as shown in  FIG. 1 . This pivoting motion causes lug  24  on the key lever  18  to clear projection  44  on the release lever  26  (since pivot  27  is higher up the latch than pivot  20 ) enabling the key lever  18  to pivot in the direction B under the influence of the resilient biasing means, and to be guided into engagement with coupling  40  by guide bars  15 . The engaged position of the key lever  18  is shown in  FIG. 2 . The lever is maintained in this engaged position by virtue of the resilient biasing means. Referring now to  FIGS. 5A and 5B , the operation of the key barrel output arm  38  is shown.  FIG. 5A  illustrates the rest position of the key barrel  36 . When a vehicle user inserts an appropriate key (not shown) into key barrel  36  and turns the key in a clockwise direction as illustrated by arrow C in  FIG. 5B , this in turn causes key barrel output arm  38  to rotate clockwise by a corresponding amount and thereby causes the upper end of key lever  18  to trace an arcuate path having a primarily vertical component to its movement. Key lever  18  is provided with some flexibility to its left and right movement as viewed in  FIGS. 5A and 5B , and therefore translates the arcuate movement at its upper end to a vertical movement at its lower end where the arm connects to the latch  12 . The appropriate vertical movement causes the latch to be switched between a locked and unlocked state. 
   Thus, it should be appreciated that the latch according to the present invention substantially simplifies the installation thereof into a vehicle door, whilst causing the connection process between the key barrel and key lever to be a simple matter of actuating the outside release handle of the door in which the latch is being installed. 
   It should further be appreciated that numerous changes may be made within the scope of the present invention. For example, the latch need not be offered up to the door as part of a door module, a similar principle may be employed in releasably restraining other levers or connectors between a door latch and input on the vehicle door. Suitable alternative formations may be employed for the interconnections between the key barrel and key lever and between the outside door release linkage and outside release lever. 
   The aforementioned description is exemplary rather that limiting. 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, one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. Hence, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For this reason the following claims should be studied to determine the true scope and content of this invention.