Patent ID: 9648955
Date: 2017-05-16
CPC Classifications: A47C

Claim:
1. A chair back elevation adjustment structure comprising: a frame, having a central trench and an adjustment board in a bottom of the central trench, the adjustment board having a limiting channel and two sliding slots beside the limiting channel, and the limiting channel having a plurality of limiting slots; a back board, connected to the frame, having a connecting end with an opening corresponding to the adjustment board in position, and fixing holes being provided around the opening; and an adjustment set, connected between the frame and the back board, comprising: a sliding seat, having passing holes and an engagement block received in the opening, and the engagement block having a recess with a through hole; a limiting body, received in the recess, having a central bar inserted into the through hole and an extending portion with a limiting bar received in the limiting channel and one of the limiting slots, and a C-shaped trench being formed around the bar; a torsion spring, received in the C-shaped trench, two ends of the torsion spring protruding from the C-shaped trench and stopped by a wall of the recess for restoring the limiting body; two sliders, separately received in the sliding slots, having penetrating holes corresponding to the passing holes and the fixing holes in position; and bolts, separately passing through the penetrating holes, the passing holes and the fixing holes and screwing with a nut for fixing the sliders and the sliding seat onto the back board.