Patent ID: 9739276
Date: 2017-08-22
CPC Classifications: F04B

Claim:
1. A piston-cylinder unit, comprising: a piston that is fluid pressure supported and movable in a linear manner in a cylinder, wherein the cylinder, a face wall of the piston and a face wall of the cylinder define a compression cavity which is at a minimum size in a portion of a top dead center of the piston, wherein the compression cavity is connected in a fluid transferring manner with a bearing gap which is formed between a cylinder inner circumferential wall and a piston outer circumferential wall, wherein a plurality of fluid outlet nozzles are arranged in at least one cross-sectional plane of the cylinder in the cylinder inner circumferential wall along the circumference, which fluid outlet nozzles open into the bearing gap, wherein the piston is provided with a ventilation groove configured as a circumferential groove into which a ventilation conduit opens, wherein the ventilation groove is configured in a circumferential section of the piston that is adjacent to the piston face wall, wherein the ventilation conduit reduces pressurized fluid entering the ventilation groove to a pressure level which is lower than a pressure in the compression cavity when the piston is in its top dead center or when it moves towards the top dead center in proximity to the top dead center, and wherein a pressure compensation circumferential groove is provided between the piston face wall and the ventilation groove.