Frequency unit valve

A frequency unit valve comprising:

• a housing communicating with a piston rod and forming an inner space, both ends of the housing being opened;
• a free piston slidably mounted on an inner peripheral surface of the housing and partitioning the inner space of the housing into an upper chamber and a lower chamber;
• a sub-valve mounted in a lower portion of the housing and allowing oil to be passed to the outside of the housing according to the sliding of the free piston;
• and
• variable frequency units installed above and under the free piston, and configured to close an oil passage of the upper and lower chambers when a frequency of the piston rod is in a high-frequency region, and open the oil passage of the upper and lower chambers through the free piston when the frequency of the piston rod is in a low-frequency region,
• wherein the free piston comprises:
• a body having an opened lower side and forming an inner space, the body being configured to move vertically within the housing according to reciprocation of the piston rod;
• a sliding flange extending from an outer peripheral surface of the body and contacting the inner peripheral surface of the housing;
• and
• a disk sheet spaced apart from the outer peripheral surface of the body on the sliding flange and protruding in a ring shape,
• wherein the variable frequency units are installed above and under the body with reference to the sliding flange.