Hydraulic unit for brake system

A hydraulic unit of a brake system, comprising:

• a housing including an inner surface having a first diameter;
• an oil supply part configured to supply oil to the housing, wherein the oil supply part is disposed to communicate with the housing;
• an oil discharge part disposed in a center region of the housing and configured to discharge the oil to an outside of the housing, wherein the oil discharge part is separated from the oil supply part, and disposed to communicate with the housing;
• a piston movably mounted on the housing, and configured to open and close the oil supply part and the oil discharge part, wherein the piston comprises:
• an opening and closing part movably mounted in the housing, and configured to open and close the oil supply part and the oil discharge part;
• a support part fixed to the inside of the housing that tapers to a second diameter less than the first diameter;
• an elastic part having one side supported by the support part and the other side contacting the opening and closing part, and configured to provide an elastic force to the opening and closing part;
• and
• a sealing part mounted on an outer surface of the opening and closing part to contact the inner surface having the first diameter of the housing,
• wherein the opening and closing part comprises:
• an opening and closing body formed in a cylindrical shape and moved in the housing while abutting on the inner surface of the housing;
• and
• an opening and closing protrusion protruding from another side of the opening and closing body, surrounding the oil discharge part, capable of contacting the oil supply part, and configured to block a flow path to which the oil discharge part and the oil supply part are connected, when contacted with the oil supply part,
• wherein the opening and closing protrusion has an inclined part which is inclined downward toward the outside from the oil discharge part,
• wherein an upper end of the inclined part is contacted with the oil supply part so as to expose a part of the oil supply part,
• wherein the housing includes at least one step portion having a third diameter wider than the first diameter,
• wherein the support part is fixed to an inside of the step portion, and
• wherein the oil supply part is disposed between the oil discharge part and the inner surface of the housing.