Patent Publication Number: US-6902213-B2

Title: Tail gate locking system

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to a tail gate locking system, and more particularly, to a rotation-absorbing device capable of absorbing rotational force of a lock lever to prevent the rotational force of the lock lever from being transmitted to a tail gate latch in a locking system. 
   BACKGROUND OF THE INVENTION 
   In a coupling structure between a tail gate lock and a tail gate latch, which are components of a tail gate locking system, the lock and latch are directly connected via either one or two rods and an intermediate crank lever. As a lock lever connected to the rod(s) is rotated right or left through a designated angle, the tail gate lock is locked or unlocked by the tail gate latch via the rod(s) connected therebetween. 
   However, where conventional coupling structures provide further function in addition to the function of controlling the locking/unlocking between the lock and latch, e.g., where it is necessary to increase the rotation angle of the lock lever by a further angle in order to control a window latch, such coupling structures may have potential problems in operation. For example, as the lock lever is rotated further, beyond the point necessary for operation of the latch, the rod(s) and the crank lever, if any, transmit the further rotational force to the latch without absorbing the further unnecessary rotational force. 
   SUMMARY OF THE INVENTION 
   In a coupling structure according to an embodiment of the present invention, a control latch is mounted to be capable of absorbing the further rotational force of the lock lever for accomplishing an additional function. Thus, both a tail gate latch and a window latch can be controlled in common with one lock without further mounting any additional device for controlling the window latch and the like. 
   In a further alternative embodiment of the present invention, a tail gate locking system comprises a lock mechanism including a lock lever. A window rod is linked to the lock lever for actuating a window latch. A first latch rod is linked to the lock lever opposite the window rod. A control latch is linked to the first latch rod opposite the lock lever, and a second latch rod is linked to the control latch for actuating a door latch. Preferably, the control latch comprises a base member and two linkage members. The first linkage member is pivotably mounted on the base member at a pivot point and defines an opening with peripheral camming surfaces. The first linkage member is also connected to the first latch rod. The second linkage member is pivotably mounted on the base member and includes a pin cooperating with the camming surface of the first linkage member. The second linkage member is connected to the second latch rod. 
   In a preferred embodiment, the camming surfaces of the first linkage member are disposed around the edges of the opening. These camming surfaces include a first camming surface corresponding to an arc defined by a first radius from the pivot point, a second camming surface corresponding to an arc defined by a second, longer radius from the pivot point, and at least a third camming surface corresponding to an arc defined by a third radius, longer than the first and second radii, extending from the pivot point. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a schematic diagram of a coupling structure according to an embodiment of the present invention; 
       FIG. 2  is a schematic diagram illustrating a control latch according to an embodiment of the invention; 
       FIG. 3A  is a diagram of a key lever according to one embodiment of the invention; 
       FIG. 3B  is a diagram illustrating an opening in the key lever of  FIG. 3A ; 
       FIG. 4  is a diagram of a remote lever according to an embodiment of the invention; and 
       FIGS. 5A  to  5 E are schematic diagrams illustrating aspects of the operational position of the control latch depending on locking, unlocking and further rotational force of a lock. 
   

   BACKGROUND OF THE INVENTION 
   The following detailed description will present a preferred embodiment of the invention in reference to the accompanying drawings. 
   As shown in  FIG. 1 , a coupling structure between a lock lever and a latch section of a tail gate  7  includes a window latch  21  connected to the lock section  1  via a window rod  19  in addition to conventional components. The lock lever  3  is connected to one end of the first rod  9  and the latch section  7  is connected to one end of the second rod  11 . A control latch  23  is connected to the opposite ends of the first rod  9  and the second rod  11  so that rotational force of the lock lever  3  caused by the window latch  21  is not transmitted to the latch section  7 . 
   As shown in  FIG. 2 , the control latch  23  includes a base  25 , an actuator  27 , a key lever  29  and a remote lever  31 . The base  25  is mounted on the tail gate, and serves to fix other components. The key lever  29  is rotatable about an axis P 1  and restricted in movement by the first rod  9  connected thereto. Key lever  29  controls axial rotation of the remote lever  31 , coupled to key lever  29  so as to restrain the position of the remote lever  31 . In a preferred embodiment, pin  34  extending from remote lever  31  acts as a cam along the periphery of opening  36  in key lever  29 . 
     FIG. 3A  is a plan view of the key lever  29  separated from the control latch  23  for the purpose of illustrating the configuration of an upper portion of the key lever  29 .  FIG. 3B  illustrates the configuration of an opening in the key lever  29 . As shown in  FIG. 3B , the periphery of the opening partially corresponds to arcs of concentric circles described, respectively, from the axis P 1  as their common center or origin. 
   As shown in  FIG. 4 , the remote lever  31 , rotatable about an axis P 2 , is axially rotated and restricted in movement owing to axial rotation of the key lever  29  so as to restrain the position of the second rod  11  coupled thereto. The control latch  23  shifts the second rod  11  for a given distance when the lock lever  3  is rotated right or left by an angle α. Control latch  23 , however, has no effect on the position of the second rod  11  when the lock lever  3  is further rotated by any angle β. 
   As shown in  FIG. 5A , the relative position between the key lever  29  and the remote lever  31  changes when the lock is moved to a locked position from an unlocked position. Displacing the lock lever  3  to the left by an angle α from the unlocked position shifts the position of the second rod  11  with a distance X. 
     FIG. 5B  shows the relative position between the key lever  29  and the remote lever  31  when a key is removed in the locked position. In this case, even though the lock lever  3  is displaced to the right by the angle α toward its original position, the second rod  11  maintains its position, shifted with the distance X, without any change in position. 
     FIG. 5C  shows the relative position between the key lever  29  and the remote lever  31  when the tail gate is unlocked from the locked position. Displacing the lock lever  3  to the right by the angle α from the locked position shifts the position of the second rod  11  by the distance X so as to return the second rod  11  into its original position. 
     FIG. 5D  shows the relative position between the key lever  29  and the remote lever  31  if the key is removed in an opened position. In this case, even though the lock lever  3  is displaced to the left by the angle α, the second rod  11  maintains its position. 
     FIG. 5E  shows the relative position between the key lever  29  and the remote lever  31  when a window is opened in the locked position. In this case, the lock lever  3  is displaced to the left by the angle β, whereas the second rod  11  maintains its position. As a result, further rotational force along the angle β does not have an effect on the position of the second rod  11 . 
   According to the coupling structure having the above construction and operation, both the tail gate latch and the window latch can be controlled in common with one lock. Further, since it is unnecessary to mount any additional device for controlling the window latch, components can be reduced in number so as to save cost as well as simplify assembly process. 
   While the present invention has been shown and described in connection with the preferred embodiment, it is intended that the present invention is not limited to the foregoing embodiment but those skilled in the art can make various modifications and variations without departing from the principle of the invention as defined in the appended claims.