Patent Publication Number: US-8967679-B2

Title: Vehicle door latch

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 61/305,795 filed Feb. 18, 2010, the contents of which are incorporated herein by reference thereto. 
    
    
     BACKGROUND 
     Exemplary embodiments of the present invention relate to door and movable panel latches and, more particularly, to door and movable panel latches for vehicles. 
     A vehicle frequently includes displaceable panels such as doors, hood, trunk lid, hatch and the like which are affixed for hinged or sliding engagement with a host vehicle body. Cooperating systems of latches and strikers are typically provided to ensure that such panels remain secured in their fully closed position when the panel is closed. 
     A door latch typically includes a fork bolt that is pivoted between an unlatched position and a primary latched position when the door is closed to latch the door in the closed position. The fork bolt is typically held in the primary latched position by a detent lever that pivots between an engaged position and a disengaged position. The detent lever is spring biased into the engaged position and thus, holds the fork bolt in the primary latched position when in the engaged position and releases the fork bolt when it is moved to the disengaged position so that the door can be opened. 
     The fork bolt is pivoted to the primary latched position by a striker attached to, for example, an associated door jamb when the door is closed. Once in the primary latched position, the detent lever engages the fork bolt to ensure the assembly remains latched. 
     Some vehicles have power unlatching mechanisms that electrically release the door latch. These power unlatching mechanisms moves the detent lever from the engaged position to the disengaged position such that the fork bolt can be rotated or pivoted to the unlatched position. However and when an external condition or force is applied to the door the door may not “pop open” freely and if the power unlatching mechanism is subsequently disengaged the detent lever returns to the engaged position by the spring biasing force and the door cannot be opened even though an electric release command was provided. 
     Accordingly, it is desirable to provide an automatically operated door latch assembly. More specifically, it is desirable to provide an automatically operated door latch assembly that employs a device or motor to move the detent lever from the engaged position to the disengaged position in order to release the striker from the fork bolt. 
     SUMMARY OF THE INVENTION 
     In accordance with an exemplary embodiment of the invention, a latch assembly is provided. The latch assembly having: a fork bolt movably secured to the latch assembly, the fork bolt being capable of movement between a latched position and an unlatched position; a detent lever movably secured to the latch assembly, the detent lever being capable of movement between an engaged position and a disengaged position, the detent lever retains the fork bolt in the latched position when the detent lever is in the engaged position and a engagement surface of the detent lever contacts an engagement surface of the fork bolt; and an actuator for moving the detent lever into the disengaged position from the engaged position, the actuator being configured to prevent the detent lever from moving back to the engaged position until the fork bolt has been moved to the unlatched position. 
     In accordance with another exemplary embodiment of the present invention, a method of preventing a detent lever of a vehicle door latch assembly from moving to an engaged position when the detent lever has been moved to a disengaged position by an actuator is provided, the method including the steps of: pivotally securing a fork bolt to the vehicle door latch assembly for movement between an unlatched position and a latched position; pivotally securing the detent lever to the vehicle door latch assembly for movement between the engaged position and a disengaged position wherein a contact surface of the detent lever engages a contact surface of the fork bolt when the detent lever is in the engaged position and the fork bolt is in the latched position; and preventing the detent lever from moving to the engaged position from the disengaged position by restricting the movement of the actuator until the fork bolt has been moved to the unlatched position. 
     Additional features and advantages of the various aspects of exemplary embodiments of the present invention will become more readily apparent from the following detailed description in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view illustrating a latch assembly in accordance with an exemplary embodiment of the present invention wherein a striker has engaged the fork bolt and has started to rotate the fork bolt from the unlatched position to the latched position; 
         FIG. 2  is a view illustrating the latch assembly of  FIG. 1  in a primary or latched position wherein the detent lever has moved to the engaged position; 
         FIGS. 3 and 4  are views illustrating the latch assembly in a primary or latched position wherein the detent lever has been moved to the disengaged position; and 
         FIG. 5  is a view illustrating the latch assembly wherein the fork bolt is in the unlatched position. 
     
    
    
     Although the drawings represent varied embodiments and features of the present invention, the drawings are not necessarily to scale and certain features may be exaggerated in order to illustrate and explain exemplary embodiments the present invention. The exemplification set forth herein illustrates several aspects of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Exemplary embodiments of the present invention relate to an apparatus and method for providing a latch assembly. Furthermore, exemplary embodiments are directed to a latch assembly having a fork bolt movably secured thereto for movement between a latched position and an unlatched position. The latch assembly further comprises a detent lever capable of movement between an engaged position and a disengaged position, wherein the detent lever retains the fork bolt in the latched position when the detent lever is in the engaged position. The latch assembly also includes an actuator for moving the detent lever from the engaged position to the disengaged position. The actuator further comprises a hold open lever for maintaining the detent lever in the disengaged position until the fork bolt is rotated into the unlatched position. 
     References made to the following U.S. Pat. Nos. 3,969,789; and 6,568,741 and U.S. Patent Publication No. 2002/0163207 the contents each of which are incorporated herein by reference thereto. 
     Referring now to  FIGS. 1-5 , a vehicle compartment latch or latch assembly  10  in accordance with an exemplary embodiment of the present invention is illustrated. As illustrated, the vehicle compartment latch  10  comprises a frame plate or support  12  that is adapted for fastening to a vehicle proximate to a compartment closure. 
     A fork bolt or fork bolt lever  16  is pivotally or rotationally mounted to frame plate  12  about a pivot pin or stud  18  that is received within a pivot pin opening of the fork bolt. Fork bolt  16  is capable of rotational or pivotal movement between an open or unlatched position and a closed or latched position shown in  FIGS. 2-5 , wherein the fork bolt rotates in the direction of arrows  20 . 
     Vehicle compartment latch  10  is attached to a vehicle structure such that fork bolt  16  is moved between the open position and the closed position when a door, window, lift gate, etc. is opened and closed and fork bolt  16  engages a striker  22  that is attached to the door, window, lift gate, etc. Alternatively, the vehicle compartment latch  10  is secured to the door, window, lift gate, etc. and the striker is secured to the vehicle body at an opening into which the door, window, lift gate, etc. is received. The cooperation of a fork bolt and striker is well known and need not be described in detail. 
     Vehicle compartment latch  10  further comprises a detent lever  24  that pivots on support or frame plate  12  about a pivot pin  26  received within a pivot pin opening in the detent lever. The detent lever cooperates with fork bolt  16  in a well known manner to retain fork bolt  16  in the closed position shown in the  FIG. 2  or release the fork bolt  16  for return to the open position. That is, detent lever  24  pivots between a closed or engaged detent position shown in the FIGS. and a release or disengaged detent position in the direction of arrows  28 . In accordance with an exemplary embodiment of the present invention, fork bolt  16  is spring biased to the open position by a biasing member (e.g., coil spring or other equivalent member) that has one end attached to fork bolt  16  and the other end attached to the housing or other equivalent location. Similarly, a biasing member or spring will also bias the detent lever in the direction of a face of fork bolt  16 . 
     In accordance with exemplary embodiments of the present invention, the fork bolt has an engagement surface or contact surface  30  that slides along and makes contact with a complimentary engagement surface or contact surface  32  of the detent lever when the fork bolt pivots or moves from the open position to the closed position and once in the closed position surface  30  of the fork bolt engages a surface  32  of the detent lever thus engaging the fork bolt and securing it into the closed position when the striker is secured in a receiving opening  34  of the fork bolt. Once the latch is in the closed position the detent lever is spring biased into contact with the fork bolt such that the fork bolt cannot rotate into the open position unless the detent lever is moved back to the release or disengaged detent position (e.g., moving surface  30  away from surface  32  allowing the fork bolt to rotate into the open position). 
       FIGS. 2-4  show structural components of a latch in a fully latched orientation. As seen, the detent lever is engaged on the primary tooth of the fork bolt lever, and each lever is capable of rotating about its respective pivot stud. The pivot studs are dual supported opposite the frame plate by a back plate (not shown). 
     In order to move the detent lever to the disengaged position, an actuator  36  provides a force to the detent lever in order to rotate it out of engagement with the fork bolt. In one implementation the actuator is electrically operated by a motor  53  illustrated schematically and coupled to the actuator  36  or more particularly the slider  42  by any suitable means, which in this implementation is an electrically powered door opener or actuator that is remotely activated by a signal, which in one non-limiting embodiment is generated or transmitted by a hand held device such as a key fob or other equivalent device. Since the detent lever is spring biased towards the fork bolt the detent lever will return to the engaged position once the force from the actuator is removed. 
     Accordingly and if the fork bolt has not been rotated to the unlatched position and the force from the remotely activated actuator is removed, the detent lever, which controls the position of the fork bolt lever, is spring biased back into the engaged position and the latch assembly is once again unable to be opened. In order to prevent this the actuator includes a hold open lever  38  that is spring biased in the direction of arrow  40  by a spring  41  such that as a slider  42  of the actuator slides in the direction of arrow  44  in order to move the detent lever into the disengaged position the hold open lever will rotate in the direction of arrow  40  and a portion  46  of the hold open lever will engage a detent or feature  48  of the slider such that the slider will remain in the position illustrated in  FIGS. 1 and 4  and thus the detent lever remains in the disengaged position until the fork bolt rotates into the unlatched position. 
     As shown in the attached FIGS. slider  42  has a pair of slotted openings  50  configured to receive pins or studs  52  and a distal end  54  of the slider is configured to engage a feature  56  of the detent lever in order to rotate the detent lever into the disengaged position when the slider moves in the direction of arrow  44 . 
     Accordingly and when the slider is moved in the direction of arrow  44  end  54  engages feature  56  and the detent lever is rotated to the disengaged position. Thereafter, the hold open lever is then rotated until portion  46  engages detent  48  and the slider is locked or held in the position illustrated in at least  FIGS. 1 and 4  wherein the detent lever is maintained in the disengaged position such that if a force is being applied to the door while the detent lever is moved to the disengaged position, the detent lever will remain in this position until the fork bolt is rotated to the unlatched position. 
     As illustrated, in  FIG. 5  fork bolt  16  is configured to have a cam surface or feature  58  configured to engage a complimentary surface  60  of the hold open lever and rotate the same in a direction opposite to arrow  40  such that portion  46  is no longer received within detent  48  of the slider. 
     Accordingly, an apparatus for preventing detent lever to engage fork bolt so that fork bolt can open when an electrically powered actuator is activated to power unlatch the door latch. 
     In one operation a door of the vehicle having a striker secured thereto remains closed due to fork bolt engaging the striker (e.g., latched position). Thereafter, a power unlatching mechanism moves the slider towards the detent lever to disengage it from the fork bolt (e.g., move it to the disengaged position from the engaged position) and allow free movement of the fork bolt. If however, the fork bolt is kept in the closed or primary latched position due to a condition or force being presented against the door of the vehicle, the detent lever remains in the disengaged position. This is achieved by a hold open lever that engages and retards movement of the slider after the slider has moved the detent lever into the disengaged position. In addition, the fork bolt is designed in such a way that as the door opens it will disengage the hold open lever. Allowing the power unlatching mechanism to go back into its home position such that the detent will be ready to engage the fork bolt on next closing or latching cycle. 
     As used herein, the terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another, and the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. In addition, it is noted that the terms “bottom” and “top” are used herein, unless otherwise noted, merely for convenience of description, and are not limited to any one position or spatial orientation. 
     The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., includes the degree of error associated with measurement of the particular quantity). 
     While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.