Abstract:
In an activation device for a vehicle seat adjuster, particularly a motor vehicle seat, possessing a pivotable hand lever ( 12 ) for manual activation, which is supported eccentrically and working in conjunction with the adjuster ( 7 ), an acceleration-sensitive feature ( 24 ) is provided to immobilize and/or lock the hand lever ( 12 ) in the event of a crash.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
         [0001]    This is a continuation of International Application No. PCT/EP01/13642, which was filed Nov. 23, 2001, published in German on Jul. 4, 2002, and is incorporated herein by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to an activation device for a vehicle seat adjuster.  
           [0003]    A known vehicle seat adjuster includes two lock fittings that are unlocked with a pivoting movement of an activation device that is in the form of a hand lever, so that the seat back can be pivoted. Because the hand lever is a one-armed design to save space, i.e. it is pivotably supported at a position that is distant from its center of gravity, there is a risk, in the event of a crash, that the hand lever, by reason of its inertia, will perform an unintended pivoting movement, thereby unlocking the lock fittings.  
           [0004]    Therefore, for an activation device for a lengthwise adjuster with a pivotable lever in the DE 196 28 716 A1, it is suggested that a spring is provided whose characteristic force curve rises sharply in the initial phase and then, after reaching a local maximum, shows a negative gradient allowing easy activation. However, in the event of sufficiently high crash forces, even the local maximum can be overcome, allowing the adjuster to unlock.  
         BRIEF SUMMARY OF THE INVENTION  
         [0005]    One aspect of the present invention is the provision of improvements to activation devices for vehicle seat adjusters. In accordance with this aspect, the activation device includes an eccentrically mounted hand lever for pivoting in response to manual activation of the hand lever, so that the pivoting of the hand lever unlocks the associated adjuster to thereby enable operation of the unlocked adjuster. The activation device also includes an acceleration-sensitive device operative for immobilizing and/or locking the hand lever in the event of a crash, whereby the unlocking of the adjuster is prevented in response to the crash. Preferably, the acceleration-sensitive device is mounted for moving from a first predetermined position into a second predetermined position in response to the crash; with the acceleration-sensitive device being operative for allowing the pivoting of the hand lever while the acceleration-sensitive device is in the first predetermined position, and the acceleration-sensitive device being operative for restricting the pivoting of the hand lever while the acceleration-sensitive device is in the second predetermined position.  
           [0006]    By virtue of the fact that there is an acceleration-sensitive device to immobilize and/or lock the hand lever in the event of a crash, the hand lever, in the event of a crash, will be secured independently of the magnitude of the crash forces, so that the adjuster does not unlock. With reference to the hand lever being eccentrically mounted for pivoting, this means that it is pivotably supported at a position that is distant from its center of gravity. The acceleration-sensitive device will preferably be a pivotably supported pendulum element, which is also preferably pivotably supported at a position that is distant from its center of gravity in order to react sensitively to accelerations in a simple fashion. For modular construction, i.e. in order to make a single-unit activation device, the pendulum element is preferably pivotably mounted on the hand lever. A more rapid response of the pendulum element in relation to the hand lever is obtained by virtue of the pendulum element having less mass than the hand lever.  
           [0007]    In a preferred construction, the pendulum element, in the event of a crash, works in conjunction with a frame-fixed component in order to lock and/or immobilize the hand lever. For this purpose, the pendulum element preferably has a convex-shaped rim which, when bearing against the frame-fixed component, produces a locking effect. The frame-fixed component, which is preferably also convex, may be an adjuster-fixed bolt, for example, which, when used, also serves as a stop for the hand lever.  
           [0008]    The activation device, according to the invention, can be used for a vehicle seat, for example in an inclination adjuster, a height adjuster, a length adjuster, or in an unlocking device for seat legs—hereinafter also called an adjuster.  
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0009]    The invention is explained in greater detail with reference to an exemplary embodiment illustrated in the drawings, wherein:  
         [0010]    [0010]FIG. 1 is a schematic lateral view of the exemplary embodiment in the resting position,  
         [0011]    [0011]FIG. 2 represents FIG. 1 in the event of a crash, and  
         [0012]    [0012]FIG. 3 is a schematic lateral view of a vehicle seat. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]    A vehicle seat  1  for a motor vehicle is equipped with a seat component  3  and a seat back  5 , which is connected with the seat component  3  on each side of the vehicle seat  1  by means of an adjuster  7  being designed as a lock fitting. By unlocking the adjusters  7 , the seat back  5  can be pivoted to the chosen inclination. The adjusters  7  are unlocked by means of an activation device  10  on one side of the vehicle seat  1 .  
         [0014]    The activation device  10  has a hand lever  12  which is mounted for pivoting relative to the adjusters  7  and fixedly mounted on a shaft  14 . The shaft  14  is working in conjunction with the adjusters  7  in such a way that, when the shaft  14  rotates, corresponding locks are moved by cam discs in a lower part of the adjuster fittings  7  and fall into or out of dentations in the upper part of the fitting. Around the shaft  14 , the hand lever  12  has a tongue-shaped area  12 ′ pointing radially in one direction; in continuation, pointing more in a tangential direction, there is an arm-shaped area  12 ″. The arm-shaped area  12 ″ has a user-accessible handgrip  16  pointing in the direction of travel, for moving the hand lever  12 .  
         [0015]    In the tongue-shaped area  12 ′ of the hand lever  12  there is a slotted link  18  in the shape of a segmental arch, which has the shaft  14  as its center. The slotted link  18  embraces a bolt  21  which is firmly fixed to the lower part of the adjuster  7  located in direct proximity to the hand lever  12 , i.e. fixed to the seat, projecting from this adjuster  7 , parallel to the shaft  14 . The bolt  21  is inside the slotted link  18 , which has an upper end that is forward with respect to the direction of travel of the automobile. The hand lever  12  is designed for an upward activation movement while the bolt  21  is at the upper end of the slotted link  18 .  
         [0016]    A small pendulum element (segment)  24  is pivotably mounted on a pin  22  at the lower edge of the slotted link  18  near its lower end, with the lower end of the slotted link being located further back than the upper end of the slotted link (relative to the direction of travel). In a resting position, the approximately quarter sector, sickle-shaped pendulum element  24  that is mounted near the center of the circle, i.e. distant from its center of gravity, hangs below the slotted link  18 . The slotted link  18 , however, is within the pivoting range of the pendulum element  24 .  
         [0017]    When the activation device  10  is used, the hand lever  12  is moved out of its resting position in such a way that the slotted link  18  is shifted over the bolt  21 , which serves as a stop, until the bolt comes close to the lower end of the slotted link  18 . Thereafter, the lever  12  is moved back into the resting position (shown in FIG. 1). The hand lever  12  is preferably held in the resting position by a spring.  
         [0018]    In the event of a crash, the inertia of the movably mounted and friction-held components causes them to be decelerated later than the frame-fixed components, i.e. to be accelerated when considered within their reference system. Therefore, in the exemplary embodiment, in the event of a head-on collision, the hand lever  12  and the pendulum element  24 , both of which are eccentrically mounted, i.e. mounted at a position that is distant from their center of gravity, are moved forward relative to the seat-fixed bolt  21 . Because the mass of the pendulum element  24  is much smaller than the mass of the hand lever  12 , the pendulum element  24  is accelerated more, thus much more rapidly causing a pivoting movement towards the front and then upward. This brings the pendulum element  24  within the range of the slotted link  18 . The dimensions of the pendulum element  24  and the position of the pin  22  are chosen so that the convex outer rim of the pendulum element  24  comes into contact with the bolt  21 , thereby immobilizing the hand lever  12  for a short time. Means may be provided, such as a stop at the hand lever  12 , to prevent further pivoting of the pendulum element  24  caused by its momentum, in case the desired relative position of the pendulum element  24  and bolt  21  has not yet been reached.  
         [0019]    In this position, the tangential surfaces in contact with the pendulum element  24  and the bolt  21  are aligned almost vertically relative to the connecting line between the pin  22  and the bolt  21 , so that a strong friction grip, or even nearly a profile grip, is produced. The friction grip is sufficient to keep the forces applied by the hand lever  12  to the pendulum element  24  from pushing the pendulum element  24  aside, i.e. the hand lever  12  cannot make a pivoting movement until the acceleration peak has leveled off. Following that, the pendulum element  24  can pivot downward again, the still-active relative acceleration no longer being sufficient to pivot the hand lever  12 . This keeps the adjusters  7  from unlocking.