Abstract:
A hood latch having an extra-long fishmouth for enabling a vehicle hood to deflect downwardly upon impact, such as when hit by a pedestrian in a frontal crash. To prevent this deflection when the hood is slammed shut in ordinary use, a stop lever is pivotally mounted to the latch housing. The stop lever features first and second arms defining a slot therein. One arm has a proboscis thereon and is biased to align the slot with the fishmouth, with the proboscis jutting into the fishmouth. The proboscis receives an impact from the striker and rotates the stop lever to a blocking position wherein the non-proboscis arm intercepts the striker and prevents it from reaching the bottom end of the fishmouth. In the closed position the ratchet retains the striker at an intermediate depth in the fishmouth, enabling the striker to travel toward the bottom end thereof.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National State of International Application No. PCT/CA2012/000058 filed Jan. 20, 2012 which claims priority to and the benefit of U.S. Provisional Application No. 61/436,233 filed Jan. 26, 2011. The entire disclosure of each of the above applications is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to the art of automotive latches, specifically hood latches. 
     BACKGROUND OF THE INVENTION 
     The automotive industry is attempting to better protect pedestrians from head on collisions with vehicles. When a car hits a pedestrian in a front collision, the pedestrian is thrown up and often lands on the front hood of the vehicle and/or the windshield. In an effort to ameliorate the harshness of the impact, it would be desirable for the front hood to not be rigidly connected to the frame, but rather flexibly coupled so that the hood has some springiness to it to somewhat absorb the impact. 
     This causes issues for the design and construction of the front hood latch. On the one hand, the hood springiness is desired. On the other hand, the hood has to open and close, and upon closing the latch it is desirable for the latch to react to the hood slam in the manner that consumers have been accustomed to, i.e., solidly, without appearing to reciprocate due to the springiness in the system. The latch must also prohibit the hood from unduly moving due to road vibrations and wind load. The invention seeks to provide a solution to at least some of these objectives. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the invention a latch is provided having a housing with an extra long fishmouth for receiving a striker. The fishmouth has an open top end and a closed bottom end, the top and bottom ends defining a depth therebetween. A ratchet and pawl combination selectively retain the striker in the fishmouth, the ratchet moving between a closed position wherein the striker is retained in the fishmouth and an open position wherein the striker is free to exit the fishmouth, the pawl moving between a locking position wherein the pawl keeps the ratchet in the closed position and an unlocked position wherein the pawl permits the movement of the ratchet out of the closed position. The ratchet is biased to the open position and the pawl is biased to the closed position. A release mechanism is provided for urging the pawl out of the locking position. A stop lever is pivotally mounted to the housing. The stop lever has first and second arms defining a slot therein. The stop lever has a proboscis on one of the arms and is biased such that the slot generally aligns with the fishmouth with the proboscis jutting into or otherwise juxtaposed so as to interfere with the fishmouth. The stop lever is mounted and configured for the proboscis to receive an impact from the striker so as to overcome the bias and rotate the stop lever to a blocking position wherein the non-proboscis arm intercepts the striker and prevents it from reaching the bottom end of the fish mouth. As such, in the closed position the ratchet retains the striker at an intermediate depth in the fishmouth, enabling the striker to travel toward the bottom end of the fishmouth when an impact, such as a pedestrian collision, provides a sufficient force on the striker . 
     According to another aspect of the invention a three position hood latch is provided with a housing having a an extra long fishmouth for receiving a striker. The fishmouth having an open top end and a closed bottom end, the top and bottom ends defining a depth therebetween. 
     A ratchet is pivotally mounted to the housing. The ratchet is moveable between (i) a primary closed position wherein the ratchet is positioned to retain the striker in the fishmouth, (ii) a secondary closed position wherein the ratchet is positioned to retain the striker in the fishmouth at a depth closer to the fishmouth top than the primary closed position, and (iii) an open position wherein the striker is free to exit the fishmouth. The ratchet is biased towards the open position. 
     A pawl is pivotally mounted to the housing. The pawl is moveable between (i) a primary locking position wherein the pawl is positioned to keep the ratchet in the primary closed position, (ii) a secondary locking position wherein the pawl is positioned to keep the ratchet in the secondary closed position, and (iii) an unlocked position wherein the pawl permits the movement of the ratchet out of the secondary closed position. The pawl is biased towards the primary and secondary locking positions. 
     A release mechanism is provided, including a primary release lever mounted to the housing for urging the pawl out of the primary locking position and a secondary release lever mounted to the housing for urging the pawl out of the secondary locking position. 
     A stop lever is pivotally mounted to the housing. The stop lever has first and second arms defining a slot therebetween. The stop lever has a proboscis on one of the arms and is biased such that the slot generally aligns with the fishmouth with the proboscis jutting into the fishmouth. The stop lever is mounted and configured for the proboscis to receive an impact from the striker so as to overcome the bias and rotate the stop lever to a blocking position wherein the non-proboscis arm intercepts the striker and prevents it from reaching the bottom end of the fish mouth. 
     As such, in the primary closed position the ratchet retains the striker at an intermediate depth in the fishmouth, enabling the striker to travel toward the bottom end of the fishmouth when an impact, such as a pedestrian collision, provides a sufficient force on the striker. 
     Preferably, the hood latch includes a manually handled presenter slidably connected to the secondary release lever, with the presenter being biased to move away from the secondary release lever so as to effectively increase the reach thereof. The presenter is preferably disposed to abut against a vehicle hood. 
     Preferably, the pawl and secondary release lever pivot about different axes, with the pawl being disposed in the rotational path of the secondary release lever when the pawl is positioned in the secondary locking position, and the pawl not being positioned in the rotational path of the secondary release lever when the pawl is positioned in the primary locking position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other aspects of the invention will be more readily appreciated having reference to the drawings, wherein: 
         FIG. 1  is a front elevation view of a latch according to a preferred embodiment, the latch being shown in an open position; 
         FIG. 2  is a rear perspective view of the latch shown in  FIG. 1 , the latch being shown in an open position; 
         FIG. 3  is a front, fragmentary, perspective view of the latch shown in  FIG. 1 , with the housing and other components removed from view, wherein the latch is shown in a primary closed position; 
         FIG. 4  is a front elevation view of the latch shown in  FIG. 1  in a first position in the process of closing; 
         FIG. 5  is a front elevation view of the latch shown in  FIG. 1  in a second position in the process of closing; 
         FIG. 6  is a front elevation view of the latch shown in  FIG. 1  in a third position in the process of closing; and 
         FIG. 7  is a front elevation view of the latch shown in  FIG. 1  in the primary closed position. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In the description that follows, reference is made to direction such as up, down, vertical, horizontal, etc. Such directions are made with reference to the orientation of the figures in the drawings, and are not intended to be limiting. 
       FIG. 1  is a front elevation of a latch  10  according to the preferred embodiment, and  FIG. 2  is a rear perspective thereof Referring initially to these drawings, the latch  10  includes a frame plate  12  that incorporates a slot or fishmouth  14  for receiving the keeper of a striker  16  (not shown in  FIGS. 1 and 2 ) mounted to the hood. The fishmouth  14  differs from the conventional in that it has an extra long depth to enable the hood to move downwardly upon impact as will be discussed in greater detail below. 
     The latch  10  also includes a cover plate  18  (seen best in  FIGS. 2 and 3 ). The frame plate  12  and cover plate  18  are interconnected by first and second rivets  20 ,  22 . The first and second rivets  20 , 22  each have integral shafts  20 A,  22 A extending beyond the cover plate  18 . 
     The frame plate  12 , cover plate  18  and interconnecting rivets provide a housing for the latch. Those skilled in the art will appreciate that a wide variety of alternative configurations may be deployed to provide the latch housing. 
     A fork ratchet  24  is pivotally mounted on the rivet  20  between the frame plate  12  and cover plate  18 . The ratchet  24  includes a hook  26  and a lip  28  that extends beyond the hook. The ratchet  24  also includes a primary shoulder stop  32  and a pointed secondary shoulder stop  34 . 
     The ratchet  24  is biased to an open position as shown in  FIGS. 1 and 2  by a first biasing mechanism, for example a substantial torsion spring  35  that is mounted on the rivet shaft  20 A and connected between the cover plate  18  and the ratchet  24 . The torsion spring  35  has tangs  35 A,  35 B. The cover plate  18  features a slot  36  for receiving spring tang  35 A, and the ratchet  24  includes a pin or rivet  38  for receiving spring tang  35 B. 
     Referring additionally to the fragmentary perspective view of  FIG. 3  (where plates  12  and  18 , rivets and torsion springs are removed from view), a pawl  40  is pivotally mounted on the rivet  22  between the frame plate  12  and cover plate  18 . The pawl  40  has a shoulder  42  that interacts with the primary and secondary shoulder stops  32 ,  34  of the ratchet  24 . The pawl  40  also features a primary release tab  44  and a secondary release tab  46 . 
     The pawl  40  is biased to a locking position as shown in  FIG. 3  (where the ratchet  24  is shown in a primary closed position) by a second biasing mechanism, for example a torsion spring  48  that is mounted on rivet shaft  22 A and connected between the other rivet shaft  20 A and the pawl  40 . The torsion spring  48  has tangs  48 A,  48 B. The primary release tab  44  receives spring tang  48 A, and the other spring tang  48 B is located under the other torsion spring  35  and supported directly by the other rivet shaft  20 A. 
     A primary release lever  50  is also pivotally mounted on the rivet  22  between the frame plate  12  and the cover plate  18 . The primary release lever  50  includes a tab  52  for connection to a release cable (not shown) that is connected to a handle (not shown) located in the vehicle compartment for initiating the opening of the hood latch. 
     The primary release lever  50  interacts with the pawl  40  via its primary release tab  44  and is thus also biased by torsion spring  48  into a non-engaged position. 
     A secondary release lever  60  is pivotally mounted on a pin  62  rigidly connected to the cover plate  18 . The secondary release lever  60  has a bend in it that provides a face  64  for interacting with the pawl secondary release tab  46 . The secondary release lever  60  also includes a presenter  66  which is intended to be gripped by hand in order to manually manipulate the secondary release lever  60 . The presenter  66  is slidably disposed along the secondary release lever  60  preferably by a pin  68  and slot  70  connection. The presenter  66  encases a coil spring  72  which is mounted on a tip  74  of the secondary release lever  60  and urges the presenter  66  upwards. 
     The secondary release lever  60  is biased to a non-engaged position as shown  FIG. 1 ,  2  or  3  by a fourth biasing mechanism, for example a torsion spring  76  that is mounted on the pin  62  and connected between the cover plate  18  and the secondary release lever  60 . The torsion spring  76  has tangs  76 A,  76 B. The cover plate  18  features a slot  78  for receiving spring tang  76 A, and the secondary release lever  60  includes a tab  80  for receiving spring tang  76 B. 
     The primary and secondary release levers  50  and  60  provide a release mechanism for opening the latch. 
     A forked stop lever  82  is pivotally mounted on a pin  84  connected to the frame plate  12 . The stop lever  82 , seen best in  FIG. 1 , is generally U or pincer-shaped, having a short stop arm  86  and a longer actuation arm  88  which together define a slot  89  therebetween. The stop arm  86  has a planar impact surface  90 , and the actuation arm features a protuberance or proboscis  92 . 
     The stop lever  82  is biased to a rest position as shown in  FIGS. 1 and 2  by a third biasing mechanism, for example a torsion spring  94  that is mounted on the pin  84  and connected between the frame plate  12  and the stop lever  82 . The torsion spring  94  has tangs  94 A,  94 B. The stop lever  82  features a tab  96  for receiving spring tang  94 A, and the frame plate  12  includes a tab  98  for receiving spring tang  94 B. 
     The latch  10  is shown in its primary closed position in  FIG. 3 , where the ratchet  24  is in a primary closed position and the pawl  40  is in a primary locking position with the pawl shoulder  42  abutting the ratchet primary shoulder stop  32 . 
     In operation, to open the latch, the primary release lever  50  is engaged by pulling on the associated handle inside the vehicle compartment, causing the primary release lever  50  to rotate clockwise in  FIG. 3 . As the primary release lever  50  rotates, it will engage the pawl primary release tab  44  causing the pawl  40 , which pivots along the same axis as the primary release lever  50 , to rotate in the same direction (clockwise in  FIG. 3 ). As the pawl  40  rotates, the pawl shoulder  42  will slip away from the ratchet primary shoulder stop  32 , enabling the ratchet  24  to rotate (clockwise in  FIG. 3 ) towards its open position due to the bias torque provided by torsion spring  35 . However, the ratchet  24  is prevented from rotating to its open position due to the ratchet secondary shoulder stop  34 , which will abut the pawl shoulder  42 , placing the ratchet  24  into a secondary closed position and the pawl  40  into a secondary locking position. 
     In the secondary closed/locking position, the ratchet  24  repositions the pawl  40  slightly causing the pawl secondary release tab  46  to come into the path of the secondary release lever interaction face  64  as indicated by the partial stippled lines  46 ′. To open the latch, the secondary release lever  60  must be manually pivoted clockwise in  FIG. 3 . It should also be noted that in the secondary closed/locking position, due to the repositioning of the ratchet  24  in comparison to its primary closed position, the hood becomes slightly elevated leaving a gap for manual access to the secondary release lever  60 . The latch presenter  66  is urged upwards due the coil spring  72 , extending the reach of the secondary release lever yet still leaving a small gap between the top of the presenter and the hood inner surface to allow for easy movement of the secondary lever. The presenter  66  is preferably manufactured in a high contrast color, e.g., yellow, to enable persons peering into the gap to ascertain the location of the secondary release lever  60 . This is particularly useful when the hood latch is located in a non-conventional location. For example, when a retracting hoods is deployed for pedestrian protection purposes, the system may employ two hood latches  10  at opposite corners of the hood. 
     When the secondary release lever  60  is manually pivoted clockwise in  FIG. 3 , the pawl  40  is also caused to rotate clockwise into an open position whereby the pawl shoulder  42  slips away from the ratchet secondary shoulder stop  34 , enabling the ratchet  24  to rotate completely into its open position as shown in  FIGS. 1 and 2  as a result of the bias torque on the ratchet  24 . 
     The stop lever  82  comes into play on closing. As illustrated in  FIG. 4 , the striker  16  first contacts the ratchet lip  28  to begin rotating the ratchet  24  towards its primary closed position (counterclockwise in  FIG. 4 ). As seen in  FIG. 5 , as the striker  16  descends into the fishmouth  14  the striker  16  impacts the proboscis  92  of the stop lever  82  which is juxtaposed to interfere with the fishmouth. The inertia provided by the impact causes the stop lever  82  to overcome the bias torque provided by torsion spring  94  and pivot the stop lever (clockwise) to the position shown in  FIG. 6 , where its planar impact surface  90  receives the impact of the striker  16  and prevents it from descending all the way to the bottom of the fishmouth  14 . As seen in  FIG. 7 , the striker  16  will slightly recoil backwards up the fishmouth  14  but the ratchet  24  will be captured by the pawl  40  in the primary closed/locking position preventing the ratchet  24  and striker  16  entrained therein from backing out of the fishmouth  14 . The bias torque on the stop lever  82  causes it to revert substantially back to its rest position, where the slot  89  in the stop lever  82  aligns with the fishmouth  14 . In this position, in the event the ratchet  24  receives a force that exceeds the substantial bias torque provided by the ratchet torsion spring  35  such as may occur when a pedestrian impacts the front hood, the striker  16  is free to move further downwardly into the fishmouth  14  thus providing the hood with a vertically downward degree of freedom. 
     Thus, the latch  10  can react to a hood slam in the solid manner that consumers have been accustomed to without appearing to unduly recess downwardly or reciprocate due to the vertical degree of freedom provided by the extra long fishmouth  14 . It will also be appreciated that if the hood is closed slowly and not slammed, the stop lever may not engage as there is no need in this case. 
     Those skilled in the art will appreciate that while the stop lever has been shown applied with respect to a three position latch moveable between primary closed, secondary closed and open positions, the same effect may be achieved if the stop lever is applied to a two position latch where a ratchet and pawl combination move only between closed and open positions. In the latter case, the latch release mechanism does not need to employ two levers to open the latch. 
     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.