Patent Publication Number: US-6666483-B2

Title: Hood latch with self-retracting secondary latch release arm

Description:
This application claims the benefit of Provisional application No. 60/176,222 filed Jan. 14, 2000. 
    
    
     FIELD OF INVENTION 
     This invention relates to a hood latch for a vehicle. In particular, this invention relates to a hood latch having a self-retracting secondary arm. 
     BACKGROUND OF INVENTION 
     Vehicle hood latch systems are well known in the art. Typically, a vehicle hood or trunk deck will have a latch for engaging and cinching onto a striker. The latch will have a rotatably mounted ratchet engaging a pawl in a ratchet relation. The ratchet cooperates with a mouth of the housing to pivot between an open and closed condition for receiving, engaging and cinching a keeper of a striker. The pawl retains the ratchet in the closed and cinched conditions. 
     Hood latches are required to have a secondary latching mechanism and a primary latching mechanism. The primary latching mechanism is operably from inside the vehicle, normally under the dashboard. A secondary latching is only operable from the outside. The secondary release lever is accessible only after the primary latching mechanism has been deployed, but is usually in a deployable position even though it is not accessible. In many cases, the location of the arm is difficult to find requiring the operator to probe blindly or bend over to look for the arm. 
     It is known to provide a release lever on the secondary latching mechanism that is presented only upon the release of the primary latch. Examples of such latch mechanism are described in U.S. Pat. Nos. 4,961,601; 4,991,884; 5,000,493 and 5,141,265. However, such mechanisms require complicated linkages and levers, adding costs to the latch. As a result, the use of self presenting secondary release arms has been limited. 
     SUMMARY OF THE INVENTION 
     The disadvantages of the prior art may be overcome by providing a hood latch assembly for a vehicle having a simple mechanism for self presenting a secondary release arm upon releasing of the primary release and which retracts upon secondary release of the hood. 
     It is desirable to provide a hood latch assembly having a retracting secondary release that is retracted independently of the closing of the hood minimizing inertial forces on the secondary release lever. 
     According to one aspect of the invention, there is provided a latch assembly that has a housing having a mouth. A ratchet is pivotally mounted to the housing and is movable to cooperate with the mouth to pivot between an open condition, a primary closed condition and a secondary closed condition for receiving, engaging and cinching a keeper of a striker. The ratchet is biased to the open condition. A pivotally mounted pawl is biased into engagement with the ratchet for releasably retaining the ratchet in the primary closed condition. A secondary release arm is mounted to rotate about a first axis and a second axis. The secondary release arm is rotatable about the first axis between a retracted position and an extended position, and is rotatable about the second axis between an engaging position and a disengaging position. The secondary release arm is biased to the retracted position and biased to the engaging position. The secondary release arm interengages with the ratchet for coupled movement therewith from the primary closed condition to the secondary closed condition effecting movement of the secondary release arm from the retracted position to the extended position upon the pawl being rotated to disengage from the ratchet. Upon moving the secondary release arm from the engaging position to the disengaging position, the secondary release arm disengages from the ratchet for independent movement enabling the ratchet to rotate from the secondary closed condition to the open condition and back to the primary closed condition. The secondary release arm also rotates from the extended position to the retracted position. 
     According to another aspect of the invention, there is provided a latch assembly having a secondary release arm that includes a plate commonly mounted for pivotal movement therewith. The plate interengaging with a ratchet. The secondary release arm is pivotally mounted in an over center and overlapping relation with the plate, enabling the plate to pivot without causing the secondary release lever to pivot, and coupling the secondary release lever to effect pivoting of the plate. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     In drawings which illustrate embodiments of the invention, 
     FIG. 1 is a perspective view of the latch assembly of the present invention; 
     FIG. 2 is a perspective view of the reverse side of the latch assembly of FIG. 1, with the back plate removed; 
     FIG. 3 is a perspective view of the latch assembly, similar to FIG. 2, but from a lower angle of view to illustrate the release lever mounting assembly. 
    
    
     DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1 and 2, the latch assembly  10  of the present invention generally has a ratchet or ratchet  12  which has a hook  15  and which is rotatable mounted on a pin  14  to pivot between an open condition, a secondary closed condition and a primary closed condition to grip a keeper of a striker. Spring  18  attaches to the ratchet  12  at aperture  17  and to housing  16  to bias ratchet  12  to a release position. Pin  14  extends between housing  16  and back plate  22 . 
     Ratchet  12  has a series of detents  24  and  26  corresponding to the open condition and the primary closed condition. Ratchet  12  has a tab or tongue  28 . Preferably, the leading edge of the tab  28  is contoured. Ratchet  12  cooperates with the mouth of the housing  16 . Pawl  40  is biased to engage ratchet  12  in a ratchet relation. The ratchet  12  cooperates with a mouth of the housing  16  to pivot between the open and primary closed or latched condition for receiving, engaging and cinching a keeper of a striker. The pawl  40  retains the ratchet  12  in the latched condition. 
     Secondary release lever  20  is mounted on a mounting assembly to provide two degrees of movement. Release lever  20  has a U-shaped base that is received between arms of upwardly extending U-shaped pivot mount  30 . Pivot  30  is pivotally mounted on flange  21  of housing  16  by pin  23  to rotate about a first axis, providing a side to side movement of the secondary release lever  20  and plate  36 . Pivot pin  34  pivotally connects release lever  20  to the mounting assembly about a second axis to provide an up and down movement as will be explained later. Preferably the first axis is orthogonal to the second axis. 
     Spring  32  extends between flange  21  and U-shaped pivot  30  to bias the mounting assembly, including release lever  20 , to the retracted position. In the retracted position, release lever  20  will be in the same general plane as the housing  16 . U-shaped pivot mount  30  pivotally receives plate  36 . Plate  36  has a U-shaped base that is fitted between the arms of the U-shaped pivot mount  30  and release lever  20 . Plate  36  has an aperture  37  that is sized to receive tab  28  of ratchet  12 . 
     Plate  36  and secondary release lever  20  has a common pivot. Preferably, secondary release lever  20  and plate  36  extend from opposite sides of the common pivot. Secondary release lever  20  extends in an over center and overlapping relation with plate  36  so that plate  36  may pivot independently of the secondary release lever  20 , but not vice versa. In other words, plate  36  may pivot without causing release lever  20  to pivot, but pivoting of release lever  20  will cause pivoting of the plate  36 . 
     Spring  38  extends between release lever  20  and plate  36  to bias plate  36  to cooperate with release lever  20 . Spring  39  extends between the plate  36  and U-shaped mount  30  to bias the plate  36  upwardly for engagement with the ratchet  12 . 
     The various elements have tabs for engaging the springs that make up the present invention. The tabs are positioned in a manner well known in the art to provide the requisite biasing as described herein. 
     Release pawl  40  is pivotally mounted on pin  42  that extends between the housing  16  and back plate  22 . Spring  44  biases the pawl into engagement with the ratchet  12 . Pawl  40  is connected to a release wire  46  in a manner well known in the art. 
     Housing  16  has a semi-tubular channel  48  which houses spring  50  which biases ratchet  12  to the release position. 
     In the release condition, the secondary release arm  20  is in the retracted condition. Upon closing the hood, the ratchet  12  receives a keeper mounted on the hood. A hood closing force will cause the ratchet  12  to rotate against the bias of spring  18  and  50  until release pawl  40  abuts against detent  26 , securing the hood in the latched condition. Tab  28  of ratchet  12  will engage plate  36  and will urge the plate  36  to deflect against the bias of spring  38  until tab  28  is received within aperture  37 . 
     Upon primary release of the ratchet  12  by retracting cable  46  from inside the vehicle, pawl  40  will rotate releasing ratchet  12  from detent  26 . Since ratchet  12  is in engagement with the release lever  20 , rotation of the ratchet  12  is a releasing direction will cause the release lever  20  to pivot from the retracted position to the secondary release position until the plate  36  contacts stop  52 . In the secondary release position, the release lever  20  will extend forwardly of the latch assembly and thus accessible from the front of the vehicle. Upon urging the release lever in an upward direction, the plate  36  will be urged away from the ratchet  12  until tab  28  disengages from the aperture  37 . The bias of spring  18  will rotate the ratchet  12  to the release condition, fully releasing the keeper and allowing the hood to be opened. Detent  24  will abut release pawl  40 . Additionally, the bias of spring  32  will rotate the release lever  20  from the release position back to the retracted position. 
     The principal advantage of the present invention is that the retraction of the secondary release lever is not dependent on the closing of the hood. 
     The preceding specific embodiment is illustrative of the practice of the present invention. It is to be understood, however, that other expedients known or apparent to those skilled in the art or disclosed herein may be employed without departing from the scope of the invention.