Adjustment structure of a seat of a chair

Abstract

An adjustment mechanism of a seat of a chair includes a frame secured to a bottom thereof, a base secured to a leg of the chair, and a lever used for locking the frame; the frame has rails, which have holding rooms therein; the base has left and right support portions respectively held in the rails so that the frame is displaceable relative to the base; the first support portion has spaced gaps formed along it; the lever is pivoted to the frame, and has an engaging end passed through a passage of the frame; the lever is biased towards a locking position by a spring, in which position the engaging end engages one of the gaps; thus, the seat can be forwards and rearwards displaced relative to the leg to change position for suiting people of different thigh lengths after the lever has been pivoted away from the locking position.

1 . An adjustment mechanism of a seat of a chair, comprising 
 a bottom frame secured to a bottom of a seat of a chair; the bottom frame having first and second rails respectively on first and second lateral sides thereof, which rails have holding rooms therein; the first rail having a passage thereon, and a pair of ear-shaped projections near to the passage on an outward side thereof; each ear-shaped projection having a through hole;    a support base securely joined to an upper end of a leg of the chair; the support base having first and second support portions on first and second lateral sides thereof; the first support portion having a plurality of spaced engaging gaps formed along it; the fist and the second support portions being respectively held in the fist and the second rails of the bottom frame and between the stopping blocks such that the bottom frame can be forwards and rearwards displaced relative to the support base; and    a lever passed through the through holes of the ear-shaped projections at a middle portion thereof; the lever having a handle portion projecting outwardly of the bottom frame; the lever having an engaging portion passed through the passage of the bottom frame; the lever being biased towards a locking position by means of an elastic element, in which locking position the handle portion thereof is directed substantially down, and the engaging portion engages one of the engaging gaps of the support base; the elastic element being positioned around the middle portion of the lever, and connected with the engaging portion, and one of the ear-shaped projections at two ends respectively;    whereby the seat can be forwards and rearwards displaced relative to the leg to change position together with the bottom frame after the lever is pivoted away from the locking position, and whereby the seat will be secured to the leg as soon as the lever is pivoted to the locking position to engage one of the engaging gaps.    
   
   
       2 . The adjustment mechanism as claimed in  claim 1 , wherein the support portions of the support base have a plurality of wheels fitted thereto, which contact inner sides of the rails of the bottom frame.  
   
   
       3 . The adjustment mechanism as claimed in  claim 1 , wherein the bottom frame has stopping blocks secured on front and rear ends of inner sides of the rails thereof, which can prevent the bottom frame from separating from the support base while the seat is displaced relative to the leg.  
   
   
       4 . The adjustment mechanism as claimed in  claim 1 , wherein a second elastic element is connected with the bottom frame, and the support base at two ends thereof respectively for helping the seat displaced in adjusting the seat.  
   
   
       5 . The adjustment mechanism as claimed in  claim 2 , wherein the support base is formed with touching projections near to the wheels on the support portions thereof, which can form frictional resistance to the rails while the bottom frame is being displaced relative to the support base.