Variable valve device

A variable valve device configured to change a valve lift amount in a cylinder head, the variable valve device comprising:

• a camshaft formed with a plurality of cams having different valve lift amounts;
• a plurality of rocker arms configured to be in contact with the plurality of cams and move a valve;
• a switching mechanism configured to couple and separate the plurality of rocker arms by oil pressure;
• and
• an oil control valve configured to control the oil pressure applied to the switching mechanism,
• wherein the switching mechanism includes a coupling piston and a separation piston configured to be moved forward and backward by the oil pressure,
• wherein the plurality of rocker arms are coupled to one another along forward movement of the coupling piston,
• wherein the plurality of rocker arms are separated from one another along forward movement of the separation piston, and
• wherein the oil control valve is configured to move the coupling piston forward at a predetermined rotation phase of the camshaft, and to move the separation piston forward at a predetermined rotation phase of the camshaft.