Electro-hydraulic variable valve lift apparatus

An electro-hydraulic variable valve lift apparatus comprising:

• a valve unit housing of which a guide protrude portion is formed therein;
• a main piston which is slidably disposed in the valve unit housing and defines a valve adjusting oil chamber with the valve unit housing;
• a main spring which is disposed within the valve adjusting oil chamber and elastically supports the main piston on the guide protrude portion;
• a dependent piston which is slidably disposed within the valve unit housing, is guided along the guide protrude portion, reciprocates according to reciprocation of the main piston, and opens a valve;
• and
• a main oil supply portion which selectively supplies hydraulic pressure to the valve adjusting oil chamber;
• wherein the dependent piston comprises:
• a first dependent piston body guided along the guide protrude portion;
• and
• a second dependent piston body guided along the valve unit housing;
• wherein the guide protrude portion, the second dependent piston body and the valve unit housing define an auxiliary chamber therebetween;
• wherein a first impact reducing oil passage is formed to the dependent piston and connects the valve adjusting oil chamber and the auxiliary chamber;
• and
• wherein the apparatus further comprises a second impact reducing oil passage which is diverged from the first impact reducing oil passage toward the guide protrude portion such that the second impact reducing oil passage is selectively blocked by the guide protrude portion in accordance with reciprocal motion of the dependent piston.