Abstract:
A door latch arrangement ( 10 ) including a latch bolt ( 12 ) releasably retainable in a closed position by a pawl ( 14 ). The pawl is connected to an inside release member ( 26 ) by a first transmission path ( 28 ). The first transmission path is interruptible by operation of a first actuator ( 32 ). The pawl is further connected to an outside release member ( 16 ) by a second transmission path ( 18 ), the second transmission path being interruptible by operation of a second actuator ( 22 ). The door latch arrangement further includes a detection device for detecting when the inside release member is operated. The first and second actuators are controlled by a control device ( 36 ), operable in response to signals from the detection device to provide for override unlocking.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application claims priority to United Kingdom (GB) Patent Application Number 0121066.5 filed on 31 Aug. 2001.  
         BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to door latch arrangements, and in particular, door latch arrangements having one pull override unlocking or two pull override unlocking.  
           [0003]    Door latch arrangements are known which include a motor operable to break or block a transmission path from an outside door handle to a pawl of the latch arrangement to provide for locking of the latch. Such latch arrangements also include a motor operable to break or block the transmission path between an inside door handle and the pawl to provide for a child safety feature. Such latches further include a mechanical linkage between the inside transmission path and the outside transmission path which operates when the inside door handle is pulled and the latch is in a locked condition to simultaneously open the door latch and unlock the door latch such that when a driver or passenger exits the vehicle and slams the door they are not inadvertently locked out of their vehicle. This is known as one pull override unlocking.  
           [0004]    Other door latches are known which include three motors, the first two operating to provide a lock function and a child safety function, as described above and a third motor operable to provide a superlock function.  
           [0005]    A problem with such known latches is that they are complicated and require many components. Furthermore, they are not interchangeable when a different operation is required.  
         SUMMARY OF THE INVENTION  
         [0006]    Thus, according to the present invention, there is provided a door latch arrangement including a latch bolt releasably retainable in a closed position by a pawl, the pawl being connectable to an inside release member by a first transmission path, the first transmission path being breakable or blockable by operation of a first actuator, the pawl further being connected to an outside release member by a second transmission path, the second transmission path being breakable or blockable by operation of a second actuator the door latch arrangement further including a detection device for detecting when the inside release means is operated, the first and second actuators being controlled by a control device, operable in response to signals from the detection means in order to provide for override unlocking.  
           [0007]    Advantageously such a system provides for override unlocking by the provision of a simple detection device. In particular, it is not required to provide a mechanical link between the inside and outside transmission paths to provide for override unlocking. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    The invention will now be described, by way of example only, with reference to the drawings in which FIG. 1 shows a schematic view of a door latch arrangement according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0009]    For the avoidance of doubt, following terms are now defined.  
         [0010]    A latch is in an unlocked security condition when operation of an inside door handle or an outside door handle causes opening of the latch.  
         [0011]    A latch is in a locked security condition when operation of an outside door handle does not unlatch the latch but operation of an inside door handle does unlatch the latch.  
         [0012]    A latch is in a superlocked security condition where operation of an outside or an inside door handle does not unlatch the latch. In particular it should be noted that multiple operations of the inside and outside door handles, in any sequence, does not unlatch the latch.  
         [0013]    A latch is in a child safety on security condition when operation of an inside door handle does not unlatch the latch but operation of an outside door handle may or may not unlatch the latch depending on whether the latch is in an unlocked or locked condition.  
         [0014]    Override unlocking is a function whereby operation of an inside door handle, with the latch in a locked condition, causes unlocking of the latch.  
         [0015]    Note that override unlocking is applicable to a latch in a locked child safety off condition, and is also applicable to a latch in a locked child safety on condition. In particular starting from a locked child safety on condition of a latch having override unlocking, an actuation of the inside handle will unlock the door, but this operation or any subsequent operation of the inside door handle will not unlatch the door since the child safety feature is on. Nevertheless, once the latch has been unlocked by actuation of the inside door handle, a subsequent operation of the outside door handle will unlatch the latch. In particular it should be noted that this situation is different from a superlocked latch since in the former case a particular sequence of handle operations, i.e. operation of the inside handle followed by operation of the outside handle, will open the door. This is not the case for superlocking.  
         [0016]    One pull override unlocking is a function whereby with the latch in a locked child safety off condition a single pull of the inside door handle results in unlocking of the door and also unlatching of the door.  
         [0017]    Two pull override unlocking is a function, whereby with the latch in a locked child safety off condition a first pull of the inside door handle results in unlocking of the latch but does not result in unlatching of the latch. However, a further operation of the inside door handle will then cause the latch to unlatch.  
         [0018]    With reference to FIG. 1 there is shown a latch arrangement  10  including a latch bolt in the form of a rotating claw  12  which can be held in a closed position by pawl  14 . In further embodiments claw  12  may have a first safety abutment for engagement by pawl  14  in order for the associated door to be held in a first safety position, where the door is not fully closed, bur nevertheless is prevented from opening.  
         [0019]    An outside door handle  16  is operably connected to the pawl via second transmission path  18 . A second break/block  20  is provided in transmission path  18 , thus dividing transmission path  18  into path  18 A which connects outside door handle  16  to the second break block  20  and path  18 B which connects the second break/block  20  to the pawl  14 .  
         [0020]    The second break/block  20  is illustrative here of two embodiments. Firstly there can be provided a break in the transmission path, such that operation of the outside door handle is possible, thus moving transmission path  18 A but in view of the break  20  transmission path  18 B does not move. Alternatively, there can be provided a block  20  such that the outside door handle and transmission path  18 A cannot be moved. Either embodiment is applicable to the present invention.  
         [0021]    Thus, with second device  20  acting to connect transmission path  18 A with transmission path  18 B or in the further embodiment with second device  20  acting so as not to block movement of transmission path  18 A, operation of the outside door handle causes transmission path  18 A to move transmission path  18 B and lift the pawl such that the claw can release an associated striker, thus enabling the door to open. Second device  20  is operable via motor  22  to move between a break/block position and a position where transmission path  18 A is connected to transmission path  18 B or where transmission path  18 A is unblocked.  
         [0022]    A latch arrangement further includes an inside door handle  26 , a first transmission path  28 , a first break/block device  30 , which divides the first transmission path into transmission path  28 A and  28 B, and a first motor  32 . Operation of these components is similar to their corresponding components associated with the outside door handle. In particular the first break/block  20  is similarly illustrative here of two embodiments. The position of the inside door handle can be determined by a detection means, in this case in the form of a switch  34 .  
         [0023]    A control device,  36  is operable to control motors  22  and  32  and hence determine the security condition of the latch. Typically, the control device  36  would be a microprocessor or an integrated control unit (ICU).  
         [0024]    In this case components  12 ,  14 ,  18 B,  20 ,  28 B,  30 ,  22 ,  32  and parts of transmission path  18 A and  28 A)are provided on a latch  38  as indicated by the dotted line. When the invention is applied to a passenger or drivers door of a car (automobile) then typically the latch  38  will be provided on a rear shut face, of the door, the outside door handle will be positioned mid way up a rear outer face portion of the door, and the inside door handle will be provided mid way up and towards the front on the inside of the door to provide for good ergonomics. The switch  34  can be provided at a suitable location either adjacent to the inside door handle or part way along transmission path  28 A or even within the latch  38 .  
         [0025]    The control device  36  can also be located at any convenient location. Note, however, that the physical position of the components shown in FIG. 1 is primarily defined by packaging requirements and is not critical to the working of the invention.  
         [0026]    The control device  36  can receive various inputs  38  which dictate the security condition of the latch as required by the user. Typically the user will be provided with door mounted, or dash board mounted switches in order for the user to be able to indicate the required security condition. Remote control devices or passive entry devices can also be used to indicate a required security condition.  
         [0027]    Possible security conditions are:  
         [0028]    locked, child safety on;  
         [0029]    locked, child safety off;  
         [0030]    unlocked, child safety on;  
         [0031]    unlocked, child safety off;  
         [0032]    superlocked.  
         [0033]    Upon receipt of an appropriate signal  38 , the control device will ensure that motors  22  and  32  move their corresponding second and first devices  20  and  30  to an appropriate position if necessary.  
         [0034]    Thus, starting from a superlocked condition, an input signal  38  requiring a change in the security condition to locked will result in motor  32  moving the first break/blocked device to a connected/unblocked position such that subsequent operation of the inside door handle will unlatch the door. Under such circumstances, the second device  20  will remain in an unchanged position ensuring that operation of the outside door handle does not unlatch the latch.  
         [0035]    In particular, it should be noted that in a superlocked condition both first and second devices  30  and  20  are in a break/block position. An input signal  38  requiring a change of security condition to locked child safety on will not result in any change to the position of the first and second devices  30  and  20 .  
         [0036]    A control device can also receive signals from switch  34  indicating the position of the inside door handle. The control device  36  can be programmed to act in either a one pull override use locking mode or a two pull override locking mode.  
         [0037]    Thus, with control device  36  programmed as a one pull override function, operation of the inside door handle with the latch in a locked condition will actuate switch  34  sending a signal  40  to control device  36  which in turn actuates motor  22  to connect/unblock second device  20  to unlock the latch whilst simultaneously the inside door handle will move transmission path  28 A and  28 B (since the latch is in a locked condition and hence the first break/block device  30  connects/unblocks transmission path  28 ) resulting in the door opening.  
         [0038]    However, with control device  36  programmed as a two pull override function, operation of the inside door handle, with the latch in a locked condition, will actuate switch  34  sending a signal  40  to control device  36  which in turn actuates motor  22  to connect/unblock second device  20  to unlock the latch. However, under these circumstances the first break/block device  30  acts to break/block the transmission path  28  hence the door does not unlatch.  
         [0039]    Once the inside door handle  26  has been returned to its rest position (which preferably can be determined by switch  34 ), only then does the control device  36  actuate motor  32  to connect/unblock first device  30 . Thus, a subsequent operation of the inside door handle will then cause the latch to open.  
         [0040]    Thus, it can be seen that providing a simple software change to the control device  36  it is possible to provide for one pull override unlocking or two pull override unlocking with the same components.  
         [0041]    Note that with the latch in an unlocked or superlocked condition, whilst switch  34  is operated as the inside door handle is operated, it is not necessary for the control device  36  to operate motors  32  or  22 .  
         [0042]    The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this invention. The scope of legal protection given to this invention can only be determined by studying the following claims.