Pump assembly, in particular for generating pressure in a brake circuit of a controllable power brake system of a motor vehicle

A pump assembly for generating pressure in a brake circuit of a controllable power brake system of a motor vehicle, the pump assembly comprising:

• a piston-cylinder unit including:
• a hollow steel piston;
• and
• a cylinder in which the piston is displaceably received and that delimits a working chamber;
• a piston drive that is configured to drive the piston and that includes:
• a nut configured to be driven for rotational movement;
• and
• a spindle that executes a translatory movement, cooperates at least indirectly with the nut, and is connected to the piston in a rotationally fixed manner;
• and
• at least one first guide element;
• wherein:
• the piston has:
• a piston skirt that is open at one axial end of the piston and that has a radially outwardly extending circumferential lip having an exterior circumferential edge, which, in at least one circumferential region of the piston, is an axial and radial terminating edge of the piston;
• and
• a piston head having a plastic deformation forming a device by which the spindle is connected to the piston in a rotationally fixed manner;
• and
• each of the at least one first guide element:
• is positioned at a respective distinct circumferential position of the lip in a respective other circumferential region of the piston;
• extends radially outward from the lip at a radial position of the lip that is radially the same as a radially outermost position to which the lip extends in the at least one circumferential region of the piston, so that an entirety of the respective first guide element is radially exterior to all of the lip;
• and
• is integrally formed with the exterior circumferential edge of the lip.