A dual-member locking mechanism for a vehicle door handle assembly activated by an inertial force acting on the locking mechanism, comprising a first lever having a first axis of rotation; and a second lever having a second axis of rotation; wherein the first lever is engageable with the door handle assembly; the second lever comprises a weight member and a finger member; the finger member is engageable with the first lever; and the second lever is rotatable around the second axis of rotation in response to the inertial force.

CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Provisional Application No. 61/033,732 filed on Mar. 4, 2008 and to Provisional Application No. 61/038,408 filed on Mar. 20, 2008, the contents of both of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a motor vehicle door handle assembly and more particularly to a locking mechanism for a motor vehicle door handle assembly which is activated by inertial forces. 
     2. Description of the Related Art 
     Typically, motor vehicles include door handles for opening doors. A door handle may include a frame and a grip. When the grip is actuated relative to the frame of the handle, the door latch mechanism is released, and the door is opened. 
     It is well-known that during motor vehicle collisions, parts of the door handle or other vehicle components may accelerate and cause unwanted actuation of the grip resulting in opening of doors. This is an undesired effect as it often leads to ejection of occupants and to greater injuries. 
     In order to prevent vehicle doors from opening during collision, various types of mechanisms have been employed. Specifically, known are mechanisms which temporarily disengage a handle from a door latch or temporarily block the transfer of forces from a door handle to a door latch during collision. 
     For example, from U.S. Pat. No. 6,712,409, known is a mechanism that includes an electrical crash sensor and a viscosity-framed crash locking unit. When the crash sensor senses collision, it electrically increases the viscosity of the medium within the crash locking unit blocking the transfer of forces from the door handle to the door latch. After collision, the viscosity of the medium is lowered, and the handle is reconnected to the door latch. 
     From U.S. Pat. No. 7,201,405, known is also a mechanism that includes a mechanical locking tab, a weight attached to a cable, and a spring. When a crash force is applied, the weight moves and causes displacement of the locking tab preventing a latch mechanism from releasing and opening the vehicle door. When the crash force is removed, the spring returns the locking tab to its original position, allowing for a transfer of forces between the handle and latch mechanism. 
     The state of the art is not fully satisfactory, however, as conventional mechanisms engage too slowly and disengage too quickly in a collision. The invention aims to remedy this situation. 
     The invention is framed on the technical problem of improving a motor vehicle door handle assembly in such a way that a door release system is reliably engaged as soon as possible after an collision and reliably disengaged only after collision forces have subsided. 
     SUMMARY OF THE INVENTION 
     In view of the above-described problems, the invention provides in one aspect a locking mechanism for a vehicle door handle assembly, which is activated by inertial forces acting on a vehicle during a collision and provides a reliable protection to occupants of the vehicle by blocking doors from opening during the collision. 
     To achieve the above objective, in accordance with one embodiment of the invention, provided is a two-member locking mechanism for a vehicle door handle assembly, comprising a first lever having a first axis of rotation; and a second lever having a second axis of rotation. 
     In one class of this embodiment, the first lever is engageable with the door handle assembly. 
     In another class of this embodiment, the second lever comprises a weight member and a finger member. 
     In another class of this embodiment, the finger member is engageable with the first lever. 
     In another class of this embodiment, within a certain angle of rotation, the first lever is rotatable around the first axis of rotation independently of the second lever, and the second lever is rotatable around the second axis of rotation independently of the first lever. 
     In another class of this embodiment, within a certain angle of rotation, the first lever is not rotatable around the first axis of rotation independently of the second lever, and the second lever is not rotatable around the second axis of rotation independently of the first lever. 
     In another class of this embodiment, the first axis of rotation and the second axis of rotation are one and the same axis. 
     In another class of this embodiment, the first lever and the second lever are spring-loaded. 
     In another class of this embodiment, the locking mechanism further comprises means for providing resistance to rotation of the first lever and the second lever. 
     In a subclass of this class, when the inertial forces acting on the locking mechanism are greater than forces exerted by the means for providing resistance to rotation, the first lever engages with the door handle assembly. 
     In another subclass of this class, when an inertial force is applied to the locking mechanism in a first direction, the first lever and the second lever rotate in concert whereby the first lever engages with the door handle assembly, and when an inertial force is applied to the locking mechanism in a second direction, the second lever rotates back to its original position and the first member continues to be engaged with the door handle assembly. 
     In another subclass of this class, the means for providing resistance to rotation is a helical spring. 
     In another class of this embodiment, the first lever further comprises a protrusion, the finger member being engageable with the protrusion. 
     In another class of this embodiment, the first lever and the second lever are secured around the first and the second axis of rotation, respectively, by a pivot bearing. 
     In another class of this embodiment, the locking mechanism is attached to the vehicle door handle assembly. 
     In yet another class of this embodiment, the mass of the weight member is greater than the mass of the finger member, and the mass of the weight member is also greater than the mass of the first lever. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described hereinafter with reference to accompanying drawings, in which: 
         FIG. 1  is a schematic side view of a vehicle door showing the position of the vehicle door handle assemblies in accordance with an exemplary embodiment of the invention; 
         FIG. 2  is a perspective view of a vehicle door handle assembly including a locking mechanism in an unlocked position in accordance with an exemplary embodiment of the invention; 
         FIG. 3  is another perspective view of a vehicle door handle assembly including a locking mechanism in a locked position in accordance with an exemplary embodiment of the invention; 
         FIG. 4  is a perspective view of the first and second levers in an unlocked position in accordance with an exemplary embodiment of the invention; and 
         FIG. 5  is a perspective view of the first and second levers in a locked position in accordance with an exemplary embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in  FIG. 1 , a handle assembly  1  is mounted along a door  10  of a motor vehicle. The handle assembly  1  is operatively connected to a door release mechanism (not shown). When the door release mechanism is unlocked, the handle assembly  1  may be actuated by a user to unlatch the door release mechanism and open the door  10 . 
     With reference to  FIGS. 2-3 , the handle assembly  1  includes a frame  2  adapted to be fixedly secured to the door  10  of the motor vehicle. A handle portion  3  (only partially shown) is pivotally coupled to the frame  2 . The handle portion  3  is manually grasped by a user and pivoted relative to the frame  2  in order to actuate the handle assembly  1  and open the door. 
     The handle assembly  1  includes a counterweight  4  pivotally coupled to the frame  2  on the pivot axis  40 . The counterweight  4  is at one of its ends connected via the connecting hole  6  and a rod (not shown) to the door release mechanism. The counterweight  4  is so set that up-and-down and side-to-side movements of a vehicle provided with the door  10  will not cause the handle  3  to move and with its movement to pivot the counterweight  4  and engage the door release mechanism. The counterweight  4  has at its other end a claw  7  for limiting the pivot angle of the counterweight  4 . The claw  7  defines a first U-shaped opening  72  and a second U-shaped opening  74 . 
     As shown in  FIGS. 2-3 , an inertia-activated locking mechanism  5  for use with the vehicle door handle assembly  1  is attached to the upper portion of the frame  2 . A lever  8  is set on an axis A which at one of its ends is connected to the frame  2 . On top of the lever  8  rests lever  9 . Both levers are rotatable around the axis A via pivot bearings  11 . The lever  9  includes a finger  91  and a weight member  92 . The weight member  92  is disposed on the opposite side of the lever  9  with respect to the finger  91 . The weight member  92  is the heaviest part of the lever  9 . A bolt member  81  and a protrusion  82  are disposed on the lever  8 . 
     A first helical spring  12  is set on the axis A between the frame  2  and the lever  8 . A spacer  14  is disposed between the lever  8  and the lever  9  for spacing the levers apart and preventing damage to the levers during their relative motion. A second helical spring  13  may be disposed on the axis A between the lever  8  and lever  9 . The springs  12 ,  13  provides resistance to rotation of the levers  8 ,  9  in both directions of motion. 
     With reference to  FIG. 4 , when the vehicle is not involved in a collision, the locking mechanism is in the unlocked position, i.e., the levers  8  and  9  are in their neutral equilibrium position and the bolt member  81  does not restrict the movement of the counterweight  4  around the axis of rotation  40 . This is to say that in the unlocked position, the movement of the counterweight  4  in the counterclockwise direction unlatches an unlocked door release mechanism. In the unlocked position, the finger  91  of the lever  8  rests against the protrusion  82 . 
     With reference to  FIG. 5 , when the vehicle is involved in a collision, initially the locking mechanism may experience a positive Y-acceleration, which will cause the weight member  92  to rotate counterclockwise around the axis of rotation A. The weight member  92  will only rotate counterclockwise around the axis of rotation A if the inertial force it experiences is larger than the sum of the stretching forces exerted by the spring  12  and the inertial force acting on the lever  8 . The lever  9  will then urge the lever  8  to rotate counterclockwise in concert with the lever  8  by the finger  91  pressing against the protrusion  82 . The mass of the weight member  92  must be higher than that of the finger  91  and the lever  8  to more than counteract the inertial forces acting on the finger  91  and the lever  8 . 
     The spring constant of the spring  12  is set so that inertial forces normally experienced during a vehicle collision will turn the lever  9  and with it the lever  8  until the bolt member  81  engages into the first U-shaped opening  72 , and the locking mechanism assumes a locked position. When the bolt member  81  engages into the first U-shaped opening  72 , the counterweight  4  is blocked from being rotated in the counterclockwise direction, and will not unlatch the door release mechanism. 
     During a later part of the collision, the locking mechanism may experience a negative Y-acceleration, which will cause the weight member  92  to rotate clockwise around the axis of rotation A back towards its equilibrium position. At this time, the lever  9  will disengage with lever  8  and will no longer urge it to rotate counterclockwise. The lever  8  will, however, remain in the locked position because the inertial forces acting upon it will now urge it to rotate counterclockwise. When the inertial forces due to a collision subside, the lever  8  will return to its equilibrium positions as shown in  FIG. 4  by the action of the spring  12 . 
     By utilizing the locking mechanism according to the invention, disengagement of the door handle is achieved at a much earlier stage during a collision as compared with conventional safety mechanisms. In addition, the mechanism remains engaged even when the acceleration changes from negative to positive, only to reengage the door handles after the collision forces have fully subsided. 
     This invention is not to be limited to the specific embodiments disclosed herein and modifications for various applications and other embodiments are intended to be included within the scope of the appended claims. While this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification, and the following claims. 
     All publications and patent applications mentioned in this specification are indicative of the level of skill of those skilled in the art to which this invention pertains. All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application mentioned in this specification was specifically and individually indicated to be incorporated by reference.