US Patent 7421993 Variable valve lift apparatus

A variable valve lift apparatus is provided comprising: an arm; a valve and valve springs connected to a first end of the arm for controlling an air intake and an air exhaust; a driving plunger disposed in a driving plunger groove formed on a second end of the arm which is opposite to the first end; a driving plunger portion elastic member disposed in the driving plunger groove for biasing the driving plunger; a support coupled to a cylinder head for supporting the driving plunger; a locking unit for selectively fixing the driving plunger; and a hydraulic pressure supply unit for selectively supplying hydraulic pressure to the locking unit.