Accumulator piston device

An accumulator piston device for a pressure medium accumulator of a hydraulic unit for brake pressure control in an electronically pressure-controllable power brake system of an electrically driven motor vehicle, comprising:

• an accumulator piston, which comprises a sleeve-shaped piston shaft and a piston crown which closes the sleeve-shaped piston shaft at one of its ends,
• wherein the piston shaft is divided in a direction of a longitudinal piston axis into successive shaft portions of different outer diameters,
• wherein outer diameters of the successive shaft portions increase in respective steps starting from a first shaft portion, on which the piston crown is arranged, the first shaft portion defining a first outer diameter that is a smallest outer diameter of the successive shaft portions,
• wherein a first step of the respective steps between the first shaft portion and a subsequent shaft portion of the successive shaft portions in the longitudinal axis of the piston forms an abutment shoulder for a seal of the accumulator piston device arranged on the first shaft portion, and
• wherein the accumulator piston includes a first guide ring on the first shaft portion, the first guide ring configured to surround the piston shaft, and
• wherein a maximum diameter of the crown is equal to or less than the first outer diameter of the first shaft portion.