Abstract:
A latch mechanism having an input member and an output member, the mechanism having a first condition at which the input and output members are coupled such that movement of the input member from its first position to its second position causes movement of the output member from its first position to its second position, the mechanism having a second condition at which the input member is not coupled to the output member, the mechanism further including a block member, which, with the mechanism in its second condition, further prevents at least one of the input and output member from moving to its respective second position.

Description:
[0001]    This application claims priority to United Kingdom (GB) Patent Application Number 0105120.0 filed on Mar. 2, 2001.  
         BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to mechanism, and particular mechanisms for use within vehicle door latches.  
           [0003]    Known vehicle door latches are lockable using a “free wheeling” principle. Thus, with the door unlocked, lifting of an outside door handle causes the door latch to open. Conversely, with the door locked, lifting of the outside door handle is still possible but the transmission path between the outside door handle and components of the door latch which retain the door in the closed position is broken. Those components on the door handle side of the break are caused to move with the door handle and those components on the other side of the break are not caused to move.  
           [0004]    A problem with this type of locking is that space has to be provided for those components on the handle side of the break to move into when the handle is lifted.  
           [0005]    Other known door locks include levers which are positioned adjacent to each other and which can be coupled and uncoupled to provide for different functioning of the door lock. However, it has been known for the levers to become artificially coupled as result of dirt and dust ingress or in even rusting of the levers. This has safety implications since the mechanism can be in an apparently uncoupled state whereas in fact actuation of an input lever will cause operation of an output lever. This is particularly so when the mechanism is used as part of a child safety mechanism on a vehicle to prevent a child from inadvertently opening the door.  
         SUMMARY OF THE INVENTION  
         [0006]    Thus, according to the present invention there is provided a mechanism having an input means and an output means, the mechanism having a first condition at which the input and output means are coupled such that movement of the input means from its first position to its second position causes movement of the output means from its first position to its second position, the mechanism having a second condition at which the input means is not coupled to the output means, the mechanism further including a blocking means, which, with the mechanism in its second condition, further prevents one of the input or output means from moving to its respective second position. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    The invention will now be described, by way of example only, with reference to the accompanying drawings in which:  
         [0008]    [0008]FIGS. 1A to  1 D show a first embodiment of the present invention in various position;  
         [0009]    [0009]FIGS. 2A to  2 D show a second embodiment of the present invention in various positions;  
         [0010]    [0010]FIG. 3 shows an isometric exploded view of FIG. 2A; and  
         [0011]    [0011]FIGS. 4A to  4 D and  5 A and  5 D show isometric views of FIG. 2A to  2 D respectively. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]    With reference to FIGS. 1A to  1 D, there is shown a mechanism  10  mounted on a chassis  12  (only shown in FIG. 1A) the mechanism  10  includes an input means in the form of an input lever  20 , an output means in the form of a pin  30 , a clutch means in the form of a link  40  and a blocking means  50 .  
         [0013]    Input means  20  is pivotally mounted at input pivot  21  to the chassis  12 .  
         [0014]    Link  40  is pivotally mounted at pivot  41  to end  20 B of input lever  20 .  
         [0015]    Blocking means  50  is fixed in a stationary position on chassis  12 .  
         [0016]    Pin  30  is movable between the position as shown in FIG. 1A and FIG. 1C. The mechanism  10  would typically form part of a vehicle door latch arrangement. An inside and outside door handle are connected by a transmission path to end  20 A of lever  20 . Pin  30  is connected to a pawl which is capable of retaining a latch bolt (e.g. a rotating claw) in a closed position. The claw in turn can releasably retain a latch striker in order to retain an associated door in a closed position. Movement of the pin  30  from the position shown in FIG. 1A to the position shown in FIG. 1C causes the pawl to disengage the claw and allow the door to open. Thus, with the mechanism in the position as shown in FIG. 1A the door is in an unlocked condition. Operation of an inside or outside door handle will cause end  20 A of lever  20  to lift (i.e. lever  20  will rotate in an anticlockwise direction) causing end  20 B to lower which results in abutment  42  contacting and then moving pin  30  to the position shown in FIG. 1C.  
         [0017]    It should be noted that in FIGS. 1A and 1C pivot  41 , abutment  42  and pin  30  are all aligned.  
         [0018]    The mechanism can be put into a locked condition as shown in FIG. 1B by rotating the link  40  so that it aligns with blocking means  50  and no longer aligns with pin  30 . Thus, where an attempt is made to lift the outside door handle abutment  42  moves into contact with blocking means  50  and the outside door handle cannot be fully lifted and the door therefore remains fully closed.  
         [0019]    However, thieves and the like tend to apply excessive force to outside door handles in the expectation of failing components of the door latch in an attempt to gain entry to the vehicle. However, the present invention mitigates this problem since in particular in the event that blocking means  50  fails (e.g., it breaks off chassis  12 ), then the abutment  42  will be caused to bypass pin  30  and thus the door still remains closed.  
         [0020]    Thus, under normal circumstances the abutment  42  does not enter the space occupied by blocking means  50 . Thus, this space is available for other components of the latch, enabling a more compact latch to be designed. Thus, typically blocking means  50  would not solely be dedicated to acting just a blocking means, but would fulfill another function within the latch.  
         [0021]    With reference to FIGS. 2A to  5 C there is shown a further embodiment of mechanism  110  with components which fulfill substantially the same function as those in latch mechanism  10  labelled  100  greater.  
         [0022]    Input lever  120  includes a hole  122  which mounts on input pivot pin  121  which in turn is mounted on chassis  112 .  
         [0023]    Input lever  120  includes a L shaped hole  123  and a further hole  124  for connection to an inside or outside door handle.  
         [0024]    In this case the output means is in the form of a lever  130  having a pivot hole  131  which is mounted on pin  121 . Thus, it can be seen that the input lever  120  and the output lever  130  lie adjacent to one another and pivot about the same axis. Lever  130  includes a slot  132  which in the position shown in FIG. 2A substantially aligns with leg  123 A of L shaped hole  123 . Output lever  130  further includes an abutment  133  and an arm  134 .  
         [0025]    Blocking means  150  is in the form of a link being pivotally mounted on chassis  112  at pivot  152  and having an abutment  153 . Adjacent abutment  153  there is a hole  154  in which is mounted pin  161  of link  160 .  
         [0026]    Link  160  includes at end  160 A clutch means in the form of a pin  140 . Pin  140  engages in L shaped hole  123  of the input lever and also in slot  132  of the output lever.  
         [0027]    Pawl arm  170  is connected at end  170 A to a pawl (not shown) which releasably retains a latch bolt (e.g. a rotating claw) to secure the door. Movement of the pawl arm  170  from the position shown in FIG. 4A to the position shown in FIG. 4C causes the pawl to rotate and allow the door to open.  
         [0028]    Operation of the mechanism is as follows.  
         [0029]    With the mechanism in the position as shown in FIGS. 2A, 3A and  4 A the pin  140  is located at end  132 A of the slot  132  and hence at end  125  of L shaped hole  123 . As such the input and output levers are coupled together for rotation. Further it can be seen from FIG. 2A that abutment  133  of the output lever is not aligned with abutment  153  of the blocking means (i.e. abutment  133 , abutment  153  and pivot  152  are not aligned).  
         [0030]    Thus, operation of an inside or outside door handle causes hole  124  to move in the direction of arrow A of FIG. 2A to the position as shown in FIG. 2C which results in arm  134  rotating pawl arm  170  and thus opening the door. It should be noted that abutment  133  has bypassed abutment  153  when considering FIG. 2C.  
         [0031]    With the input and output levers in the position shown in FIG. 2A the block means  150  can be rotated to the position as shown in FIG. 2B. This has two effects namely:  
         [0032]    a) Abutment  153  aligns with abutment  133  (i.e. abutments  153 ,  133  +-and pivot  152  are aligned) to prevent movement of output lever  130 , and  
         [0033]    b) Pin  140  is moved (by link  160 ) to end  132 B of the slot  132  and hence to the confluence of arms  123 A and  123 B of L shaped hole  123  i.e. to position  126  (see FIG. 3).  
         [0034]    In the event that an inside or outside door handle is operated, then movement of the input lever causes arcuate arm  123 B of L shaped hole  123  to move past pin  140  which remains stationary. Compare FIGS. 2B and 2D.  
         [0035]    In the event that the input and outside levers corrode or otherwise stick together then the door is still prevent from opening by engagement between abutment  133  and  153 . Under these circumstances, it is not possible to move the associated door handle and this acts as an indicator that the mechanism is malfunctioning. Such an indicator is useful since a malfunction can be determined simply by attempting to operate the door handles and no internal examination of the door is required.  
         [0036]    The mechanism can be used in the transmission path between an outside door handle and a latch bolt (i.e., it can be used to lock the door).  
         [0037]    Alternatively, the mechanism can be used between both the inside and outside door handles and the latch bolt i.e. it can be used to superlock (or deadlock) the door.  
         [0038]    Alternatively, it can be used between an inside door and a latch bolt, especially on a rear door of a vehicle, i.e. to provide a child safety function of the door latch.  
         [0039]    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.