Patent ID: 7645328

Claim:
An adsorption dryer for gaseous media having at least one pressure vessel arranged between a bottom distributor plate and a top distributor plate comprising connection channels and ports for the gaseous media, the at least one pressure vessel having a cylindrical chamber for a drying agent, the cylindrical chamber supported on its bottom and top by a bottom-end piston and a top-end piston, respectively, each piston sealed against a wall of the cylindrical chamber, support for at least one of the bottom and the top of the cylindrical chamber provided by a gas-permeable plate held on the respective piston with a compression spring, and wherein the cylindrical chamber is connected by lines sealed off from the connection channels in the distributor plates, wherein at least one of the bottom-end piston and the top-end piston on an annular outer edge turned away from the drying agent has a step and the wall of the chamber on the inside has an annular groove opposite the step to form a tongue and groove connection, a spring element seated in the annular groove and on the step limits the movement of the respective piston towards the adjacent distributor plate.