Apparatus for adjusting the angle of a seat back of an office chair

Abstract

An apparatus for adjusting the angle of a seat back of an office chair includes: a supporting base; a seat body mounted on the supporting base; a seat back having a pair of elongated ears symmetrically parallel to each other and disposed at the bottom end of both sides thereof, the elongated ears each being pivotally connected to the rear side of the seat body; and an elastic support element slantly disposed at a lower location between the bottom end of the seat back and the rear end of the seat body. Based upon the above-mentioned configuration, a strong elastic supporting force is provided for the seat back. As a result, the inclination of the seat back can be automatically adjusted when the body of the user leans backward.

1 . An apparatus for adjusting the angle of a seat back of an office chair, comprising:
 a) a supporting base having a shaft in the middle thereof;   b) a seat body having a shaft socket at the center of the bottom side thereof, the shaft socket being mounted on the shaft;   c) a seat back having a pair of elongated ears symmetrically parallel to each other and disposed at the left and right sides thereof, the elongated ears each being pivotally connected by a first pivot element to a first mounting portion at the rear side of the seat body, a projecting ear being positioned at the center between the left and right elongated ears  61  of the seat back; and   d) an elastic support element having a first pivoting portion at the top end thereof, the first pivoting portion being pivotally connected by a second pivot element to the projecting ear of the seat back, a second pivoting portion being disposed at the bottom end of the elastic support element and pivotally connected by a third pivot element to a second mounting portion of the shaft socket positioned at the bottom end of the seat body such that the elastic support element is slantly disposed at a lower location between the bottom end of the seat back and the rear end of the seat body, the elastic support element further having a guide bar pivotally connected at the bottom end of the first pivoting portion, the bottom portion of the guide bar axially passing through a socket above the second pivoting portion and in an inclined position, the socket being axially fixed within a hollow tube with an opening directed upwards, a spring being mounted on the guide bar and the socket.   
   
   
       2 . The apparatus for adjusting the angle of a seat back of an office chair as recited in  claim 1 , wherein the first, second, and third pivot elements are selected from a group consisting of a bolt and a pin. 
   
   
       3 . The apparatus for adjusting the angle of a seat back of an office chair as recited in  claim 1 , wherein the second pivoting portion and the socket of the elastic support element are integrally formed to be an L-shaped body.