Apparatus for opening and closing door

An apparatus for opening and closing a door, comprising a hydraulic hinge including a rotary member and a fixed member;

• wherein the rotary member includes:
• a first housing adapted to fix to one side of a door;
• a piston guide placed inside the first housing;
• a rotary shaft disposed inside the piston guide and fixed to the first housing so that the rotary shaft rotates when the door is opened and closed;
• and
• a piston screwed with the rotary shaft to be rotatably elevated along the piston guide when the rotary shaft rotates;
• wherein the fixed member includes:
• a second housing adapted to fix to one side of a doorframe and screwed with the piston guide;
• a cylinder placed inside the second housing and having an oil outlet penetrating the cylinder for allowing oil to pass through the oil outlet;
• a head mounted on a top surface of the cylinder;
• an adjusting bolt screwed with the head such that an oil circulating passage is formed in the fixed member for adjusting an amount of oil outflow;
• and
• an outflow part formed on the top surface of the cylinder and having a plurality of support protrusions formed on the outflow part for allowing the oil outlet to communicate with the oil circulating passage.