Mechanism for a Chair

Abstract

The mechanism which is designed for a chair, in particular for a rotatable office chair with a gas spring which is arranged in a vertical manner in the lower frame of said chair and has a telescopically extendable piston rod for adjusting the height of a seat, has the effect that the adjustment of the inclination of the seat is synchronous with the adjustment of the inclination of the backrest. The mechanism has a base ( 20 ) which is stationary per se, through which a stationary first rotary shaft (D 1 ) extends and on which a seat support which can be inclined is mounted. A front connecting means ( 21 ) which is connected in an articulated manner in a stationary third rotary shaft (D 3 ) on the base ( 20 ) and in a moveable fourth rotary shaft (D 4 ) is arranged between the base ( 20 ) and the seat support. The mechanism also has a rear connecting means ( 24 ) which is connected in an articulated manner in a moveable sixth rotary shaft (D 6 ) at one end and in a further moveable rotary shaft (D 5 ) at the other end. The mechanism contains at least one first spring element ( 26 ) which acts between the base ( 20 ) and the seat support and is connected in an articulated manner in the fourth rotary shaft (D 4 ). At the other end, this first spring element ( 26 ) is connected in an articulated manner in a moveable eighth rotary shaft (D 8 ) whose position can be varied by means of a gear mechanism ( 25 ) which can be operated by the user from the outside. The first spring element ( 26 ) is advantageously a gas spring which can be blocked by means of a locking element ( 218 ) which can be operated by the user and with which the seat and backrest are locked in the in-operative position.

1 . A mechanism ( 2 ) for a chair, in particular for a rotatable office chair with a pneumatic spring ( 12 ) which is arranged vertically in the substructure ( 1 ) and has a telescopically extensible piston rod for adjusting the height of a seat ( 4 ), whereas:
 a) the inclining adjustment of the seat ( 4 ) is synchronous with an inclining adjustment of a backrest ( 5 );   b) the mechanism ( 2 ) has a fixed base ( 20 ), through which a fixed first axis of rotation (D 1 ) extends and on which an inclinable seat carrier ( 22 ) is mounted;   c) arranged between the base ( 20 ) and the seat carrier ( 22 ) is a front connecting means ( 21 ), which is articulated along a fixed third axis of rotation (D 3 ) on the base ( 20 ) and along a movable fourth axis of rotation (D 4 );   d) a rear connecting means ( 24 , 24 ′) is provided and is articulated, on the one hand, along a movable sixth axis of rotation (D 6 ) and, on the other hand, along a movable further axis of rotation (D 5 ,D 7 );   e) the mechanism ( 2 ) contains at least one first spring element ( 26 ), which acts between the base ( 20 ) and the seat carrier ( 22 ) and is articulated along the fourth axis of rotation (D 4 ), characterized in that   f) the first spring element ( 26 ) is also articulated along a movable eighth axis of rotation (D 8 ), which can be changed in position by means of a gear mechanism ( 25 ) which can be actuated by the user from the outside.   
   
   
       2 . The mechanism ( 2 ) as claimed in  claim 1 , characterized in that
 a) the gear mechanism ( 25 ) is articulated along a fixed second axis of rotation (D 2 ), which extends through the base ( 20 ), along the eighth axis of rotation (D 8 ) and along a movable ninth axis of rotation (D 9 );   b) in the rest position, with the seat ( 4 ) positioned, at least in principle, horizontally and the backrest ( 5 ) located vertically, the second axis of rotation (D 2 ), the eighth axis of rotation (D 8 ) and the ninth axis of rotation (D 9 ) are located at least essentially vertically one above the other, and   c) in the relaxed position, with the seat ( 4 ) inclined up to a maximum extent and the backrest ( 5 ) inclined up to a complementary maximum extent, the eighth axis of rotation (D 8 ) is displaced, in the direction of the third axis of rotation (D 3 ), in front of the second axis of rotation (D 2 ) and the ninth axis of rotation (D 9 ) moves, in the opposite direction, behind the second axis of rotation (D 2 ).   
   
   
       3 . The mechanism ( 2 ) as claimed in at least either of  claims 1  and  2 , characterized in that
 a) the first spring element ( 26 ) is a pneumatic spring ( 26 ) with a cylinder ( 260 ) and a telescopically extensible piston rod ( 262 );   b) the piston rod ( 262 ) is extended to the greatest extent in the rest position, with the eighth axis of rotation (D 8 ) moved all the way downward, and is retracted to the greatest extent in the relaxed position, with the eighth axis of rotation (D 8 ) moved all the way upwards; and   c) the piston rod ( 262 ) is articulated along the fourth axis of rotation (D 4 ) by means of an intermediate component ( 27 ).   
   
   
       4 . The mechanism ( 2 ) as claimed in at least one of  claims 1  to  3 , characterized in that
 a) the mechanism ( 2 ) contains, within it, pairs of spring units ( 28 ) which are supported, on the one hand, in a bearing ( 207 ) of the base ( 20 ) and, on the other hand, beneath bearing strips ( 29 ), in bearing blocks ( 293 ), the bearing strips ( 29 ) being joined to the base ( 20 ) from both sides; and   b) the bearing strips ( 29 ) preferably consist of plastic and thus form self-lubricating bearing locations along with the joined-on, preferably metallic components.   
   
   
       5 . The mechanism ( 2 ) as claimed in at least one of  claims 1  to  4 , characterized in that
 a) the front connecting means ( 21 ) is designed as a plate-like lever, through which the axes of rotation (D 3 ,D 4 ) extend; and   b) the rear connecting means ( 24 , 24 ′) comprises a sixth axial rod (A 6 ) and a sleeve component ( 240 ), which is connected thereto via arms ( 242 ), or a sixth axial rod (A 6 ) and a seventh axial rod (A 7 ), which is connected thereto via arms ( 242 ′), the associated axes of rotation (D 5 ,D 6 ,D 7 ) extending through these axial rods.   
   
   
       6 . The mechanism ( 2 ) as claimed in at least one of  claims 1  to  5 , characterized in that
 a) a backrest carrier ( 23 , 23 ′) can be articulated along the axis of rotation (D 1 ), within the base ( 20 ), or a pair of side members ( 6 ) can be articulated outside the base ( 20 ), in order for the backrest ( 5 ) to be fastened thereon; and   b) the bearing strips ( 29 ) have stubs ( 2920 , 2921 ) for penetrating into the front lever ( 21 ) and the intermediate component ( 27 ), and they also have mounts ( 295 , 298 ) for accommodating the ninth axial rod (A 9 ), which passes through the gear mechanism ( 25 ), and for accommodating the sixth axial rod (A 6 ).   
   
   
       7 . The mechanism ( 2 ) as claimed in at least one of  claims 1  to  6 , characterized in that
 a) an arresting element ( 218 ), which can be actuated by the user, is arranged on the intermediate component ( 27 ) for blocking the pneumatic spring ( 26 ) with optional switching functions; and   b) the arresting element ( 218 ) acts on a valve stem which is guided in the piston rod ( 262 ) of the pneumatic spring ( 26 ).