Abstract:
A double pawl latch having a ratchet ( 14 ), a primary pawl ( 34 ) interacting with the ratchet ( 14 ), a secondary pawl ( 44 ) interacting with the primary pawl, and a pawl lever ( 54 ) interacting with the secondary pawl. The ratchet ( 14 ) has a single notch ( 26 ) which interacts with the primary pawl ( 34 ) to keep the ratchet ( 14 ) in a full striker capture position. In the event the primary pawl ( 34 ) is unintentionally released, the pawl lever ( 54 ) includes a backup pawl ( 64 ) that interacts with the ratchet single notch ( 26 ), keeping the ratchet ( 14 ) in an intermediate striker retaining position where the latch is still closed. The pawl lever ( 54 ) initiates the opening of the latch by withdrawing the backup pawl ( 64 ) from the path ( 26′ ) of the ratchet ( 14 ) and by actuating the secondary pawl ( 44 ). Momentum from the seal force thereafter drives the primary and secondary pawls open, but in the event the momentum is insufficient the pawl lever ( 54 ) can sequentially also open the main pawl ( 34 ) after actuating the secondary pawl ( 44 ).

Description:
FIELD OF THE INVENTION 
       [0001]    The invention generally relates to the art of vehicular latches and more specifically vehicular latches that utilize double pawl arrangements. 
       BACKGROUND OF THE INVENTION 
       [0002]    Double pawl arrangements are known in the latching art. The double pawl arrangement may utilize a first pawl and ratchet set connected to a second pawl and ratchet. The connection may be configured such that only a portion of the forces experienced by the first pawl and ratchet set are applied to the second pawl and ratchet set, thus requiring only a relatively low effort to release the latch. While this is desirable, it also leads to the problem that an unbalanced force may unintentionally release the latch in unintended circumstances such as a crash situation. It would be desirable to preclude such events. 
         [0003]    Further, in some jurisdictions regulations require side door latches to provide fully closed and intermediate closed positions. This is conventionally achieved by designing the ratchet to have two notches on the ratchet profile that are engaged alternatively by a pawl that keeps the latch at a fully closed or partially closed position. The conventional approach limits the freedom in minimizing the dimensions and the weight of the ratchet and will cause also design complexity in double pawl latches. A more elegant solution is sought. 
       SUMMARY OF THE INVENTION 
       [0004]    One broad aspect of the invention relates to a vehicle latch having a ratchet with a single notch that is utilized to hold the ratchet in either a full striker capture position or an intermediate partial striker retaining position where the latch still remains closed. 
         [0005]    According to this aspect of the invention, a vehicle latch is provided including a ratchet having a single notch, a primary pawl having a shoulder for engaging the ratchet notch, and a pawl lever having a backup pawl for engaging the ratchet notch. The ratchet is movable between a striker release position, wherein the ratchet is positioned to receive a striker, and a full striker capture position, wherein the ratchet is positioned to retain the striker, the ratchet preferably being biased towards the striker release position. The primary pawl is movable between a ratchet holding position, wherein the shoulder is positioned to engage the notch in order to keep the ratchet in the full striker capture position, and a ratchet release position, wherein the primary pawl permits the movement of the ratchet out of the full striker capture position, the primary pawl preferably being biased towards the ratchet holding position. The pawl lever is movable between an initial position, in which the backup pawl is situated in the path of the ratchet notch so as to hold the ratchet in an intermediate striker retaining position in the event the primary pawl unintentionally moves out of the ratchet holding position, and an actuated position, in which the pawl lever initiates the opening of the latch and the backup pawl is withdrawn from the path of ratchet notch, the pawl lever preferably being biased towards the initial position. 
         [0006]    Another aspect of the invention relates to the arrangement of a double pawl latch. According to this aspect of the invention a latch is provided having a housing, a ratchet, a primary pawl, a secondary pawl and a pawl release lever. The ratchet is pivotally mounted in the housing for rotation about a first axis. The ratchet is movable between a striker release position, wherein the ratchet is positioned to receive a striker, and a full striker capture position, wherein the ratchet is positioned to retain the striker. The ratchet is preferably biased towards the striker release position. The primary pawl is pivotally mounted in the housing for rotation about a second axis. The primary pawl is movable between a ratchet holding position, wherein the primary pawl keeps the ratchet in the full striker capture position, and a ratchet release position, wherein the primary pawl permits the movement of the ratchet out of the full striker capture position. The primary pawl is preferably biased towards the ratchet holding position. The secondary pawl is pivotally mounted in the housing for rotation about a third axis. The secondary pawl is movable between a primary pawl blocking position, wherein the secondary pawl inhibits movement of the primary pawl from its ratchet holding position, and a primary pawl non-blocking position, wherein the secondary pawl allows movement of the primary pawl into its ratchet release position. The secondary pawl is preferably biased to the primary pawl blocking position. The pawl lever is pivotally mounted in the housing for rotation about a fourth axis. The pawl lever has a first portion for engaging the secondary pawl and a second portion for engaging the primary pawl. The pawl lever is movable between an initial position in which the pawl lever does not engage the secondary pawl and primary pawl, and an actuated position, in which the pawl lever actuates at least the secondary pawl to move the secondary pawl into its primary pawl non-blocking position. The pawl lever is preferably biased towards the initial position. 
         [0007]    Another aspect of the invention relates to a low effort quick release of the foregoing latch. According to this aspect, when the latch is closed, the ratchet ( 14 ) is in its full striker capture position, the primary pawl is in its ratchet holding position, and the secondary pawl is in its primary pawl blocking position. These components are configured such that a seal force applied to the ratchet is translated to an opening force applied by the primary pawl against the secondary pawl in a direction substantially crossing the third rotational axis. In this manner, there is no moment on the secondary pawl when the latch is closed. 
         [0008]    However, actuation of the pawl lever causes movement of the secondary pawl so as to change the direction of the opening force away from the third rotational axis, enabling momentum from the ratchet to drive the primary pawl into the ratchet release position. 
         [0009]    And in the event the aforesaid momentum is insufficient to move the primary pawl into its ratchet release position, the pawl lever is configured to sequentially actuate the primary pawl via the second portion after the first portion of the pawl lever has actuated the secondary pawl into the primary pawl non-blocking position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The foregoing and other aspects of the invention will be more readily appreciated having reference to the drawings, wherein: 
           [0011]      FIG. 1  is a perspective view of a portion of a latch with cover partially removed from view; 
           [0012]      FIG. 2A  is a plan view of a portion of the latch shown in  FIG. 1  in a full closed position; 
           [0013]      FIG. 2B  is a plan view of a portion of the latch shown in  FIG. 1  in an intermediate or partially closed position; 
           [0014]      FIG. 3A  is a plan view of a portion of the latch shown in  FIG. 1  in a partially actuated position; 
           [0015]      FIG. 3B  is a plan view of a portion of the latch shown in  FIG. 1  in an open position; 
           [0016]      FIG. 4A  is a plan view of a portion of the latch shown in  FIG. 1  in an outside handle enabled state; and 
           [0017]      FIG. 4B  is a plan view of a portion of the latch shown in  FIG. 1  in an outside handle disabled or double lock state. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0018]      FIG. 1  is a perspective view of a latch  10  in a fully closed position. The latch  10  has a ratchet  14  that is pivotally mounted within a frame or housing  12  (only partially shown) for rotation about a rotational axis  15 . The housing  12  features a fish-mouth or slot  18  in which the striker may travel, and the ratchet  14  features a hook  22  for retaining the striker  20  in the slot  18 . The ratchet  14  pivots between a full striker capture position wherein the striker  20  is captured by the hook  22  of the ratchet  14 , as shown in  FIG. 1 , and a striker release position wherein the striker  20  is not trapped by the hook  22  and free to move out of the slot  18 . The ratchet  14  can also move to an intermediate striker retaining position as shown in  FIG. 2B  and discussed in greater detail below. (In the orientation of  FIG. 1  the ratchet  14  will rotate clockwise to move into the intermediate striker retaining position and/or into the striker release position.) 
         [0019]    The ratchet  14  is biased to the striker release position. This may be carried out via a biasing spring (not shown) or by other forces applied on the latch. 
         [0020]    The ratchet  14  also has a single shoulder or notch  26  for checking the opening urge of the ratchet  14 . Notably, this notch  26  is utilized to check the ratchet  14  in the full striker capture position and in the intermediate striker retaining portion, as discussed in greater detail below. 
         [0021]    A primary pawl  34  is pivotally mounted in the housing  12  for rotation about another rotational axis  35 . The primary pawl  34  moves between a ratchet holding position where the primary pawl  34  checks the opening movement of the ratchet  14  from its full striker capture position, as shown in  FIG. 1 , and a ratchet release position ( FIG. 3B ) where the primary pawl  34  does not interfere with the opening movement of the ratchet  14  into its intermediate striker retaining position and/or striker release position. (In the orientation of  FIG. 1  the primary pawl  34  will rotate counterclockwise to leave the ratchet holding position.) 
         [0022]    The primary pawl  34  features a hook shoulder  36  for engaging the ratchet notch  26  and is preferably biased to the ratchet holding position via a spring (not shown) or other biasing member. Opposite hook shoulder  36  the primary pawl  34  includes a ridge  40  and a cam profile  42 , the purpose of which is discussed below. 
         [0023]    A secondary pawl  44  is pivotally mounted in the housing  12  for rotation about yet another rotational axis  45 . The secondary pawl  44  moves between a primary pawl blocking position at one end of its travel where the secondary pawl  44  inhibits the opening movement of the primary pawl  34  from its ratchet holding position, as shown in  FIG. 1 , and a primary pawl non-blocking position ( FIG. 3A  or  FIG. 3B ) where the secondary pawl  44  allows the opening movement of the primary pawl  34  into its ratchet release position. (In the orientation of  FIG. 1  the secondary pawl  34  will rotate counterclockwise to leave the primary pawl blocking position.) 
         [0024]    The secondary pawl  44  features a cam follower profile  46  that engages the primary pawl cam profile  40 . The secondary pawl  44  is preferably biased to the primary pawl blocking position via a spring or other biasing member (not shown). The secondary pawl  44  also includes a lever arm  48 , the purpose of which is discussed below. 
         [0025]    A pawl lever  54  is pivotally mounted in the housing  12  for rotation about a rotational axis  55 . The pawl lever  54  interacts with at least the secondary pawl  44 , and as discussed in greater detail below, may interact with the primary pawl  34  and ratchet  14 . 
         [0026]    More particularly, the pawl lever  54  has a depending post  56  that interacts with the secondary pawl lever arm  48  in order to move the secondary pawl  44  out of its primary pawl blocking position. The pawl lever  54  also includes a depending finger  58  that may interact with the ridge  40  of the primary pawl  34 . (Note that finger  58  does not contact or otherwise engage the primary pawl hook shoulder  36 —only ridge  40  which is set back from shoulder  36 .) Additionally, a backup pawl  64  is mounted to the pawl lever  54  via a rigid connection and rotates in conjunction therewith. The backup pawl  64  may interact with the primary pawl  34  hook shoulder  36  under certain conditions as discussed below. 
         [0027]    The pawl lever  54  moves between a initial position at one end of its travel as shown in  FIG. 1  where the pawl lever  54  does not engage or actuate the secondary pawl  44  or primary pawl  34 , and an actuated position, as exemplified in  FIG. 3B , in which the pawl lever  54  moves away from its initial position and actuates at least the secondary pawl  44  so as to move the secondary pawl  44  into its primary pawl non-blocking position. The pawl lever  54  and backup pawl  64  are preferably biased to the rest position by a biasing spring or other biasing member (not shown). 
         [0028]    The latch preferably also includes an inside handle lever (not shown) which is kinematically coupled to actuate the pawl lever  54  via tab  66 . The inside handle lever is kinematically connected to an inside handle (not shown) on the vehicle door via well known mechanisms such as a rod or Bowden cable. 
         [0029]    Similarly, an outside handle lever  74  is pivotally mounted in the housing  12  for rotation about a rotational axis  75 . The outside handle lever  74  is kinematically connected to an outside handle (not shown) on the vehicle door via well known mechanisms such as a rod or Bowden cable. A sliding lock link  80  selectively couples or decouples the outside handle lever  74  with the pawl lever  54 . More particularly when the lock link  80  is positioned as shown in  FIG. 1  or  FIG. 4A , arm  76  of the outside lever  74  is coupled to tab  68  of the pawl lever  54  and the outside lever  74  is enabled to actuate the pawl lever  54 . However, when the lock link  80  is positioned as shown in  FIG. 4B , the outside lever arm  76  is decoupled from tab  68  and does not have sufficient reach to engage tab  68  thus disabling the outside handle lever from actuating the pawl lever  54 . 
         [0030]    The sliding lock link  80  may be moved into its coupling or decoupling position by a manual mechanism, such as a mechanical connection with a lock button, or electronically by a small motorized actuator. 
         [0031]    As noted above, the ratchet  14  has only a single shoulder or notch  26  for checking the opening urge of the ratchet  14 .  FIG. 2A  shows the ratchet  14  in its full striker capture position, where the notch  26  is engaged by the primary pawl hook shoulder  36 . However, as discussed below, the latch requires a low release effort to open it and therefore circumstances could arise especially in the case of a motor vehicle accident or where extraneous forces cause the primary pawl  34  to move out of its ratchet holding position, as shown in  FIG. 2A . In this case the pawl lever  54  presents the backup pawl  64  which remains in the rotational path of the ratchet  14  in order to check the opening urge of the ratchet  14  and maintain it in the intermediate striker retaining position, as shown in  FIG. 2B . Likewise, on door closing, in the event the vehicle door is closed with a weak force such that the ratchet  14  is not rotated all the way back to its full striker capture position as shown in  FIG. 2A , the bias on the pawl lever  54  will urge the backup pawl  64  into the rotational path of the ratchet  14  so that it can be held in the intermediate striker retaining position as shown in  FIG. 2B . In this manner ratchet  14  may be reduced in size (in comparison to double notch ratchets) and its single notch utilized to maintain the ratchet in either the full striker capture position or the intermediate striker retaining position. 
         [0032]    The opening sequence of the latch, and the low release efforts required to open the latch, may be understood with reference to  FIGS. 2A ,  3 A and  3 B. 
         [0033]      FIG. 2A  shows the latch in its fully closed position when the ratchet  14  in its full striker capture position. In this position there exists a force Fs on the ratchet  14  that is a reaction to the seal force when the vehicle door is closed. The force Fs along with the ratchet bias force presents a moment M 1  on the ratchet  14  that is received by the primary pawl  34  at hook shoulder  36  and shown as force Fp. The force Fp will be correlated to the moment M 1  and the relative radial distance between the striker  20  and primary pawl/ratchet contact area as measured from the ratchet rotational axis  15 . The force Fp is presented eccentric to the primary pawl rotational axis  35  that counteracts the primary pawl bias force to thus present a moment M 2  on the primary pawl  34 . The primary pawl cam profile  42  and the inter-engaging secondary pawl cam follower profile  46  (at portion  46   a ) are configured to translate the moment M 2  into an opening force Fo applied substantially through the secondary pawl rotational axis  45  such that, in the fully closed position, there is substantially no opening moment applied to the secondary pawl  44 . 
         [0034]    To open the latch, the pawl lever  54  is actuated by either the inside lever or outside lever. As the pawl lever  54  pivots away from its initial position, the depending post  56  interacts with the secondary pawl lever arm  48  and moves the secondary pawl  44  out of its primary pawl blocking position, as shown in  FIG. 3A . In this position the primary pawl cam profile  42  engages portion  46   b  of secondary pawl cam follower profile  46 , which is configured to apply the force Fo eccentric to the secondary pawl rotation axis  45  causing a moment M 3  greater than the opposing moment provided by the secondary pawl biasing force. Consequently, at the position shown in  FIG. 3A , a momentum is present whereby the seal force Fs continues to apply moment M 2  on the primary pawl  34  which in turn continues to apply moment M 3  on the secondary pawl  44  and thus the secondary pawl will continue to rotate away from its primary pawl blocking position without any further input from the pawl lever  54 , as shown in  FIG. 3B . (Note in  FIGS. 3A and 3B  the pawl lever depending finger  58  has not yet engaged the primary pawl ridge  40 .) At a certain point, as shown in  FIG. 3B , the moment M 2  moves the primary pawl  34  into its ratchet release position wherein the primary pawl hook shoulder  36  disengages from the ratchet notch  26 , enabling the ratchet  14  to move into its striker release position. 
         [0035]    It should also be noted that, as seen in  FIG. 3A , the initial actuation of the pawl lever  54  causes the backup pawl  64  to move out of the path of the ratchet notch  26 , as represented by stippled line  26 ′. Thus, the mechanism for keeping the ratchet  26  in the intermediate striker retaining portion is withdrawn or disengaged upon opening the latch. 
         [0036]    In the event there is an insufficient seal force to drive the “quick release” of the primary pawl  34  and the secondary pawl  44 , the pawl lever  54  does incorporate depending finger  58  for engaging ridge  40  of the primary pawl  34  so as to drive the primary pawl  34  into its ratchet release position. However, in normal operation, as discussed above, the momentum provided ultimately by the seal force will cause a quick release of the main and secondary pawls based on a relatively shallow pull of the pawl lever  54 . 
         [0037]    While the above describes a particular embodiment(s) of the invention, it will be appreciated that modifications and variations may be made to the detailed embodiment(s) described herein without departing from the spirit of the invention.