Piston pump

A piston pump for a vehicle brake system, comprising:

• a pump housing (12) and a piston (18) that is driven to execute a reciprocating stroke motion and is received axially displaceably in a bore (14) in the pump housing (12);
• a fluid inlet (52) and a positive displacement chamber (42) formed in the pump housing;
• a body (24, 26, 40;
• 92 94, 96), having at least a first portion and a second portion, axially displaceably received in the pump housing (12), the first portion being positioned closer to the positive displacement chamber (42) than the second portion, wherein the body (24, 26, 40, 92, 94 96) is axially displaceable relative to the piston (18) and reacts to a force of a spring element (34), the body increasing a cross sectional area of the piston (18), and
• wherein the fluid inlet (52) is positioned closer to the second portion of the body than to the first portion of the body (24, 26, 40;
• 92, 94, 96), and discharges into the bore (14);
• and a fluid opening (48, 50) is provided in the piston and connects the fluid inlet (52) to the positive displacement chamber (42).