Patent ID: 8128171

Claim:
An armrest assembly, comprising: an armrest support; a mounting sleeve movably mounted on the armrest support; an armrest mounted on the mounting sleeve to move in concert with the mounting sleeve; and a lifting device mounted between the armrest support and the mounting sleeve and operable between a first position where the lifting device is locked to lock the mounting sleeve onto the armrest support and a second position where the lifting device is unlocked to unlock the mounting sleeve from the armrest support so that the mounting sleeve is movable relative to the armrest support freely; wherein the lifting device includes: a housing secured in the armrest support and having an inner portion provided with a plurality of locking grooves; a mounting plate mounted on an upper end of the mounting sleeve to move in concert with the mounting sleeve; a control bar pivotally mounted in the mounting sleeve and having a lower section movable in the housing and an upper section movable between the mounting plate and the mounting sleeve; a locking block mounted on the lower section of the control bar to move in concert with the control bar and detachably locked in any one of the locking grooves of the housing; a control knob mounted on the upper section of the control bar and movable toward the mounting plate to move the control bar relative to the housing and to move the locking block to detach from any one of the locking grooves of the housing; and an elastic member mounted between the mounting plate and the control knob to move the control knob outwardly relative to the mounting plate and to move the locking block toward any one of the locking grooves of the housing; the mounting sleeve has a top provided with a hollow support arm for mounting the armrest; the control bar of the lifting device has a mediate portion provided with a pivot shaft pivotally mounted between the mounting plate and the mounting sleeve.