Piston pump for brake

A piston pump for a brake, comprising:

• a piston moved by rotation of a motor cam, and installed in a piston housing so as to linearly move;
• a sleeve installed in a shape to cover an end of the piston, and having an inner space for storing brake oil moved from the piston;
• an airtight mounting part coupled to the end of the piston, and blocking the brake oil from moving between the piston and the sleeve;
• a return spring having two axial ends contacted with the sleeve and the airtight mounting part, and elastically pressing the airtight mounting part toward the motor cam;
• an inlet ball pressed toward the piston by an inlet spring installed in the airtight mounting part, and installed in contact with the airtight mounting part;
• and
• a check valve installed at a position facing the sleeve, and configured to discharge the brake oil in the sleeve to the outside of the sleeve when the pressure of the brake oil rises,
• wherein the piston comprises:
• a piston body having an inner passage through which the brake oil is moved;
• and
• an insertion protrusion extended from the piston body toward the airtight mounting part, and inserted into the airtight mounting part, and
• wherein the airtight mounting part has a groove into which the insertion protrusion of the piston is inserted, wherein due to the insertion of the insertion protrusion, a width of the groove before the insertion protrusion is inserted into the groove is smaller than the width after the insertion protrusion is inserted into the groove.