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CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 13/348,828 filed Jan. 12, 2012, which claims the benefit of U.S. Provisional Application No. 61/432,831 filed Jan. 14, 2011. The entire disclosure of each of the above applications is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a closure latch for a vehicle door, and more particularly to a closure latch with a ratchet and a mechanical linkage for operatively connecting a door handle to the ratchet. 
       BACKGROUND 
       [0003]    Vehicle door latches typically include as a minimum a ratchet that holds a striker, and a pawl that releasably holds the ratchet closed. When a person wishes to open a vehicle door, the person pulls a door handle to move the pawl out of the way of the ratchet, and the person typically opens the door at the same time, so as the pull the striker from the ratchet bringing the ratchet to an open position. Additionally, vehicle manufacturers sometimes design the vehicle door so that the seal on the door (i.e., the door seal) urges the door open once the door handle is pulled, so as to assist in pulling the striker from the ratchet. As the vehicle ages however, or in certain conditions, such as very cold weather, the door seal force typically decreases. In a situation where there is a delay between when the door handle is pulled and when the door is opened, the pawl can inadvertently wind up in a position whereat it obstructs the ratchet from releasing the striker. In such a situation the person opening the door must pull on the door handle a second time and then open the door immediately, which can be inconvenient. 
         [0004]    It would be beneficial to provide a closure latch that permits a delay between when the door handle is pulled and when the door itself is opened. 
       SUMMARY 
       [0005]    One aspect provides a vehicle latch that includes a ratchet, a pawl, a memory lever and a release lever. During opening of the latch and door, the memory lever is movable to a pawl blocking position to prevent the pawl from obstructing the ratchet from releasing the striker in the event of a delay between when a door handle is pulled and when the door is opened. 
         [0006]    In a particular embodiment, the ratchet is movable between an open position wherein the ratchet is positioned to receive a striker and a closed position wherein the ratchet is positioned to retain the striker. The ratchet is biased towards the open position. The pawl is movable between a ratchet locking position wherein the pawl is positioned to hold the ratchet in the closed position and a ratchet release position wherein the pawl permits the movement of the ratchet out of the closed position. The pawl is biased towards the ratchet locking position. The memory lever is movable between a pawl blocking position in which the memory lever prevents movement of the pawl to the ratchet locking position and a pawl unblocking position wherein the memory lever permits movement of the pawl to the ratchet locking position. The memory lever is biased towards the pawl blocking position. The release lever is movable between a first position in which the release lever prevents movement of the memory lever to the pawl blocking position and a second position in which the release lever permits movement of the memory lever to the pawl blocking position and permits movement of the pawl to the ratchet release position. The release lever is biased towards the first position. The release lever is operatively connectable to at least one of an inside door handle and an outside door handle for movement to the second position. In an event in which the release lever is moved to the second position and the ratchet is restrained from movement to the open position, movement of the memory lever to the pawl blocking position drives the pawl to the ratchet release position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The present invention will now be described by way of example only with reference to the attached drawings, in which: 
           [0008]      FIGS. 1-10  are plan views of a closure latch for a vehicle door in accordance with an embodiment, in a range of positions; and 
           [0009]      FIGS. 11-17  are plan views of a closure latch for a vehicle door in accordance with another embodiment, in a range of positions. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    Reference is made to  FIG. 1 , which shows a vehicle latch  10 , for receiving and holding a striker  12 . The vehicle latch  10  may be mounted on a vehicle closure panel such as a vehicle door (not shown), while the striker  12  may be mounted on a vehicle body (not shown). Alternatively, the vehicle latch  10  may be mounted on the vehicle body and the striker  12  may be mounted on the vehicle closure panel (e.g. vehicle door). 
         [0011]    The latch  10  includes a primary ratchet  18 , a primary pawl  20 , an auxiliary ratchet  22 , an auxiliary pawl  24 , a memory lever  25  and a release lever  26 . The primary ratchet  18  is pivotally mounted to a latch housing (not shown) on the vehicle door for pivotal movement between an open position ( FIG. 7 ) wherein the primary ratchet  18  is positioned to receive or release the striker  12 , and a closed position ( FIG. 1 ) wherein the primary ratchet  18  is positioned to retain the striker  12 . The primary ratchet  18  is biased towards the open position by a ratchet biasing member  28 , which may be, for example, a torsion spring. 
         [0012]    The primary ratchet  18  includes a slot  30  that is configured to hold the striker  12  when the primary ratchet  18  is in the closed position ( FIG. 1 ), thereby preventing the striker  12  from being withdrawn from the primary ratchet  18 . The slot  30  is also configured to cooperate with the striker  12  such that when the striker  12  is initially received in the slot  30 , the striker  12  urges the rotation of the primary ratchet  18  towards its closed position ( FIG. 1 ). 
         [0013]    The primary pawl  20  is pivotally mounted to the auxiliary ratchet  22  for movement about a primary pawl pivot axis shown at  32 . The primary pawl  20  is movable between a ratchet locking position ( FIG. 1 ) wherein the primary pawl  32  holds the primary ratchet  18  in the closed position ( FIG. 1 ), and a ratchet release position ( FIG. 5 ) wherein the primary pawl  20  permits the movement of the primary ratchet  18  out of the closed position. The primary pawl  20  is biased towards the ratchet locking position ( FIG. 1 ) by a primary pawl biasing member  34 , which may be, for example, a torsion spring. 
         [0014]    The primary pawl  20  includes a primary pawl locking surface  36  which engages either a primary ratchet locking surface  37   a  to lock the primary ratchet  18  in the closed position ( FIG. 1 ) or a second ratchet locking surface  37   b  to lock the primary ratchet  18  in an intermediate closed position ( FIG. 10 ). 
         [0015]    The auxiliary ratchet  22  is pivotally mounted to the latch housing (not shown) about an auxiliary ratchet pivot axis  40  for movement between a pawl disabling position ( FIG. 5 ) wherein the auxiliary ratchet  22  positions the primary pawl  20  in the ratchet release position, and a pawl enabling position wherein the auxiliary ratchet  22  is reset, as shown in  FIG. 8  and as described in greater detail below. As seen in  FIG. 1 , a primary pawl retainer member  42  on the auxiliary ratchet  22  cooperates with a corresponding retainer member  43  on the primary pawl  20  to limit the rotation of the primary pawl  20  relative to the auxiliary ratchet  22 . Because the position of the auxiliary ratchet  22  thus controls at least to some extent the position of the primary pawl  20 , the auxiliary ratchet  22  may be said to be operatively connected to the primary pawl  20 . 
         [0016]    The auxiliary ratchet  22  may be biased towards the pawl disabling position by an auxiliary ratchet biasing member  44 , which may be, for example, a torsion spring. 
         [0017]    The auxiliary pawl  24  is pivotally mounted to the latch housing (not shown) about an auxiliary pawl pivot axis for movement between an auxiliary ratchet locking position ( FIG. 1 ) wherein the auxiliary pawl  24  is positioned to hold the auxiliary ratchet  22  in the pawl enabling position, and an auxiliary ratchet release position ( FIG. 2 ) wherein the auxiliary pawl  24  is positioned to permit the movement of the auxiliary ratchet  22  out of the pawl enabling position to its pawl disabling position. 
         [0018]    The auxiliary pawl  24  is biased towards the auxiliary ratchet locking position by an auxiliary pawl biasing member  46 , which may be, for example, a torsion spring. 
         [0019]    The memory lever  25  is pivotally mounted to the latch housing (not shown), optionally about the same axis as the primary ratchet  18 , for movement between a pawl blocking position ( FIG. 6 ) in which the memory lever  25  prevents movement of the primary pawl  20  to the ratchet locking position and a pawl unblocking position ( FIG. 9 ) wherein the memory lever  25  permits movement of the primary pawl  20  to the ratchet locking position. The memory lever  25  is biased towards the pawl blocking position by a memory lever biasing member  102 , which may be, for example, a torsion spring. 
         [0020]    The release lever  26  includes a first arm  120  which engages a corresponding arm  122  on the auxiliary pawl  24 . The release lever  26  further includes a second arm  124  that engages a pin  126  on the memory lever  25 . The release lever  26  is pivotally movable between a first position ( FIG. 9 ) in which the release lever  26  drives the auxiliary pawl  24  to the auxiliary ratchet release position and in which the release lever  26  permits the memory lever  25  to move to the pawl blocking position, and a second position ( FIG. 6 ) in which the release lever  26  permits movement of the auxiliary pawl  24  to the auxiliary ratchet locking position and in which the release lever  26  prevents movement of the memory lever  25  to the pawl blocking position. 
         [0021]    The release lever  26  is biased towards the second position by a release lever biasing member  104 , which may be, for example, a torsion spring. The release lever biasing member  104  is configured to rotate the release lever  26  with sufficient force to overcome the force with which the memory lever  25  is rotated towards the pawl blocking position. It will be noted that in the embodiment shown in  FIGS. 1-10 , the memory lever  25  is engaged with the release lever  26  and so the memory lever biasing member  102  assists in urging the release lever  26  towards its first position. 
         [0022]    A mechanical linkage  48  operatively connects one or both of an inside door handle  90  and an outside door handle  92  to the primary pawl  20  for moving the pawl to the ratchet release position ( FIG. 5 ) and for moving the memory lever  25  to the pawl blocking position. The mechanical linkage  48  may have any suitable structure. For example, the mechanical linkage  48  may include cables  94  and  96  that connect between the door handles  90  and  92  respectively and the release lever  26 . In an alternative embodiment the cables  94  and  96  may connect between the door handles  90  and  92  and another lever (not shown), which actuates the release lever  26 . 
         [0023]    The mechanical linkage  48  may be the primary means of operatively connecting the inside and outside door handles  90  and  92  to the release lever  26 . Alternatively the mechanical linkage  48  may be a backup means for use in the event of failure of a primary means that is electrically powered. Alternatively, it is possible that the mechanical linkage  48  can be omitted and that an electrically powered means (e.g. using a bidirectional electric motor) is the only means for operatively connecting the inside and outside door handles  90  and  92  to the release lever  26 . 
         [0024]    Operation of the latch  10  is described as follows. In the position shown in  FIG. 1 , the latch  10  is closed. Actuation of the inside or outside door handle  90  or  92  causes movement of the release lever  26  from the first position ( FIG. 1 ) to the second position ( FIG. 2 ). Movement of the release lever  26  to the second position drives movement of the auxiliary pawl  24  to the auxiliary ratchet release position ( FIG. 2 ). Movement of the auxiliary pawl  24  to the auxiliary ratchet release position permits movement of the auxiliary ratchet  22  to the pawl disabling position ( FIGS. 3-5 ), which brings the primary pawl  20  to the ratchet release position ( FIGS. 3-5 ). 
         [0025]    Movement of the release lever  26  to the second position ( FIG. 2 ) additionally permits movement of the memory lever  25  from the pawl unblocking position ( FIG. 1 ) towards the pawl blocking position ( FIG. 6 ). Initially, prior to movement of the primary pawl  20  out of the way, the memory lever  25  comes to rest in abutment with the primary pawl  20  as shown in  FIG. 2 . The force of the memory lever biasing member  102  causes the memory lever  25  to exert a force F 1  on the primary pawl  20 , which in acts in a direction shown at  150 . The force F 1  acts generally through the axis of rotation  32  of the primary pawl  20  and therefore does not exert a large moment on the primary pawl  20  itself. However, the force causes the primary pawl  20  to generate a counterclockwise moment on the auxiliary ratchet  22  about the auxiliary ratchet rotation axis  40 , which drives the auxiliary ratchet  22  towards its pawl disabling position. As the auxiliary ratchet  22  moves upwards towards the pawl disabling position it brings the primary pawl  20  upwards with it. Once the primary pawl  20  moves upwards sufficiently (i.e., to the position shown in  FIG. 4 ), the memory lever  25  rotates to its pawl blocking position (as shown by the progression of movement of the memory lever  25  in  FIGS. 5 and 6 ). 
         [0026]    It will be noted that  FIG. 5  differs from  FIG. 4  in that  FIG. 5  shows the primary pawl  20  having moved upward on its own (i.e., without being pulled upwards by the auxiliary ratchet  22 ). This is due to momentum in the primary pawl  20  that drives it upwards slightly after the auxiliary ratchet  22  has stopped moving. Without the memory lever  25  moving in to block it, the primary pawl  20  would return under spring pressure back to a position where it could inadvertently engage the primary or secondary surfaces  37   a  or  37   b  on the ratchet  18  and thus prevent the opening of the ratchet  18 , if the ratchet  18  itself had not opened quickly enough. A situation in which the ratchet  18  might not open quickly enough would be where the door seal force is not sufficient, due for example, to cold weather or to aging. 
         [0027]    If the person opens the vehicle door while pulling the door handle  90  or  92 , the striker  12  is pulled from the primary ratchet  18  and the primary ratchet  18  moves to its open position as shown in  FIG. 7 . At this point, a drive mechanism  140  under the control of a controller  141  will attempt to move the latch  10  to a reset position after a selected period of time has passed. Initially, the drive mechanism  140  (including, for example, a motor  142 ) moves the auxiliary ratchet  22  to the pawl enabling position ( FIG. 8 ). If the person has still not released the door handle  90  or  92  at this point, the release lever  26  remains in the second position, and therefore the memory lever  25  remains in the pawl blocking position, and thus the primary pawl  20  remains blocked by it, as shown in  FIG. 8 . Furthermore, the release lever  26  prevents the auxiliary pawl  24  from moving to the auxiliary ratchet locking position. When the person does release the door handle  90  or  92 , the release lever biasing member  104  drives the release lever  26  to its first position, which in turn drives the memory lever  25  to its pawl unblocking position at which point the primary pawl  20  comes to rest against the radial edge  170  of the primary ratchet  18 , as shown in  FIG. 9 . In the position shown in  FIG. 9 , the latch  10  may be said to be in the reset position. 
         [0028]    If, however, the person did not open the door after pulling the door handle  90  or  92 , and if the door seal force was not sufficient to pull the striker  12  from the primary ratchet  18 , then the drive mechanism (not shown) would attempt to move the latch  10  to the reset position while the primary ratchet  18  was not yet open. In such a situation, if the person continued to hold the door handle  90  or  92  open, the release lever  26  would remain in the second position, and the memory lever  25  would remain in the pawl blocking position ( FIG. 8 ). As a result, when the drive mechanism would reset the auxiliary ratchet  22  to the pawl enabling position, the primary pawl  20  would rest against the memory lever  25 . As a result, when the person finally opened the door (while continuing to hold the door handle  90  or  92  open at least for an initial portion of the door travel), the primary pawl  20  would be prevented from engaging the first or second ratchet locking surfaces  37   a  ( FIG. 1) and 37   b  ( FIG. 8 ), and so the striker  12  would be pulled from the primary ratchet  18  bringing the primary ratchet  18  to its open position. At this point, if the person released the door handle  90  or  92 , the release lever biasing member  104  would drive the release lever  26  to its first position, which in turn would drive the memory lever  25  to its pawl unblocking position at which point the primary pawl  20  would come to rest against the radial edge  170  of the primary ratchet  18 , as shown in  FIG. 9 . 
         [0029]    With the latch  10  in the reset position in  FIG. 9 , closing the door would bring the striker  12  into the slot  30  of the primary ratchet  18  and would drive the primary ratchet  18  towards its closed position. If the door was not closed with enough force, the primary ratchet  18  may only be driven to a partially closed position in which the primary pawl  20  would engage the second ratchet locking surface  37   b . If the door was closed with sufficient force, the primary ratchet  18  would be driven to a closed position in which the primary pawl  20  engages the primary ratchet locking surface  37   a  and holds the primary ratchet  18  in the closed position ( FIG. 1 ). 
         [0030]    Reference is made to  FIGS. 11 and 11   a , which shows a latch  200  in accordance with another embodiment. The latch  200  does not include an auxiliary ratchet and an auxiliary pawl. It includes a ratchet  202 , a pawl  204 , a memory lever  206 , a block lever  208  and a release lever  210 . The ratchet  202  may be similar to the ratchet  18  ( FIG. 1 ) and is biased towards the open position by a  10  ratchet biasing member  203 . 
         [0031]    The pawl  204  may be similar to the pawl  20  ( FIG. 1 ) and is biased towards the ratchet locking position by a pawl biasing member  205 , however the pawl  204  is pivotally mounted to the latch housing shown at  212 . The pawl  204  includes several features which are on different planes and are configured for engagement with several other latch components. For example, the pawl  204  includes a ratchet/pawl locking surface  270  configured to engage the first or second ratchet/pawl locking surfaces  272  or  274  ( FIG. 17 ) on the ratchet  202  to hold the ratchet  202  in the closed position. 
         [0032]    The pawl  204  further includes a first pawl/release lever engagement surface  280  that is engageable with a first pawl/release lever engagement surface  278  when the release lever  210  moves towards the second position ( FIG. 16 ), to assist in moving the pawl  204  to the ratchet release position ( FIG. 17 ). The pawl  204  further includes a second pawl/release lever engagement surface  281  which is engageable with a second pawl/release lever engagement surface  282  on the release lever  210  when the release lever  210  moves to the first position, to assist in ensuring that the pawl  204  reaches the ratchet locking position when the latch  200  is closed, as shown in  FIG. 11 . 
         [0033]    The pawl  204  further includes a pawl/memory lever engagement surface  284  that is engageable with a pawl/memory lever engagement surface  286  when the memory lever  206  moves towards the pawl blocking position, to assist in moving the pawl  204  to the ratchet release position ( FIGS. 14-16 ). 
         [0034]    The surfaces  270 ,  281  and  280  are on a different plane of the pawl  204 , than the surface  284 . The portion of the pawl  204  in the plane with the surface  284  is shown as transparent so assist in showing the surfaces  270 ,  281  and  280  underneath and other components that would otherwise be obscured. 
         [0035]    The memory lever  206  may be similar to the memory lever  25  ( FIG. 1 ) and is biased towards the pawl blocking position by a memory lever biasing member  207 . 
         [0036]    The block lever  208  permits an operative connection between the release lever  210  and the memory lever  206 . In some embodiments, it would be possible to arrange the release lever  210  in such a way so as to cooperate directly with the memory lever  206  instead of cooperating with the memory lever  206  though the block lever  208 . The block lever  208  is movable between a memory blocking position ( FIG. 11 ) and a memory unblocking position ( FIG. 16 ). 
         [0037]    The block lever  208  is biased towards the memory blocking position ( FIG. 11 ) by a block lever biasing member  214 , which may be, for example, a torsion spring. 
         [0038]    The release lever  210  may be similar to the release lever  26  and is biased towards a second position ( FIG. 11 ) by a release lever biasing member  275 , which may be, for example, a torsion spring. 
         [0039]    Inside and outside door handles shown at  216  and  218  are operatively connected to the release lever  210  by means of a mechanical linkage  220  which may include cables  222  and  224 . 
         [0040]    In operation, a person pulls a door handle  216  or  218  which moves the release lever  210  to the second position as shown by the progression of movement of the release lever  210  in  FIGS. 11-16 . Movement of the release lever  210  drives the pawl  204  counterclockwise towards its ratchet release position ( FIG. 16 ) and additionally moves the block lever  208  towards its memory unblocking position ( FIG. 16 ). 
         [0041]    The progression of movement shown in  FIGS. 11-17  will now be described. If a person pulls the door handle  216  or  218  the release lever  210  is moved from the first position ( FIG. 11 ) towards the second position ( FIG. 16 ). At some point along its travel, as shown in  FIG. 12 , the release lever  210  engages the block lever  208  moving it towards its memory unblocking position. At some point along its travel, as shown in  FIG. 13 , the release lever  210  engages the pawl  204  moving it towards its ratchet release position, and moves the block lever  208  further towards its memory unblocking position. As can be seen in  FIG. 13 , the block lever  208  has moved sufficiently to bring the memory lever  206  into engagement with the pawl  204 . The pawl  204  while having moved by some amount is still engaged with the ratchet  202 . As shown in  FIG. 14 , at some point along the travel of the release member  210 , the orientations of the pawl  204  and the memory lever  206  are such that the direction line shown at  226  through which the memory lever  206  engages the pawl  204  exerts a moment on the pawl  204  urging it towards its ratchet release position. As shown in  FIG. 15  at some point the release lever  210  stops engagement with the pawl  204 , and simply moves the block lever  208  towards its memory unblocking position, which frees the memory lever  206  to move further towards its pawl blocking position, and to urge the pawl  204  farther towards the ratchet release position. In the position shown in  FIG. 15 , the direction line of engagement between the ratchet  202  and the pawl  204  may also be such that the ratchet  202  exerts a moment on the pawl  204  urging the pawl  204  towards its ratchet release position. However in a situation where the door seal force is low or where for some other reason the ratchet  202  fails to move the pawl  204  sufficiently and where the user holding the door handle  90  or  92  has not held it sufficiently open, the memory lever  206  will move the pawl  204  to the ratchet release position and as the memory itself to the pawl blocking position in the process. 
         [0042]    In  FIG. 16  the memory lever  206  reaches the pawl blocking position, and holds the pawl  204  in the ratchet release position, so that the pawl  204  will not interfere with the opening of the ratchet  202 . Once the pawl  204  is no longer engaged with the ratchet  202 , the ratchet  202  is free to move to its open position ( FIG. 17 ). 
         [0043]    While the above description constitutes a plurality of embodiments of the present invention, it will be appreciated that the present invention is susceptible to further modification and change without departing from the fair meaning of the accompanying claims.

Summary:
A closure latch for a vehicle door is provided. The closure latch includes an emergency lock actuator to permit a person to lock the door in the event that the power lock actuator is unusable. The latch also includes an ‘impatient passenger’ feature, which permits the doors to be unlocked using the remote keyless-entry feature on the key fob even in a situation where an ‘impatient passenger’ had prematurely lifted the door handle of the vehicle. In some prior art latches, such an action by an ‘impatient passenger’ would prevent the drive motor on the latch from unlocking the latch, thereby necessitating the owner to press the unlock button on the key fob a second time. There is some overlap in the components that used for the ‘impatient passenger’ feature and the components used for the emergency lock actuator, thereby reducing cost and complexity of the latch.