Filtering apparatus

A filtering apparatus, comprising:

• a filter housing having a filter inlet for fluid to be filtered and a filter outlet for filtered fluid;
• a plurality of filter elements in said filter housing, each said filter element having an effective filter surface and a clean side;
• a backwasher backwashing and cleaning said effective filter surface of at least one of said filter elements during a filtering operation;
• a pressure control device supporting backwashing by said backwasher, said pressure control device including a hydraulic accumulator having a clean fluid chamber fillable with a quantity of cleaned fluid during the filtering operation and connectable to said filter element being backwashed by said backwasher by a backwashing guide and having a gas chamber acted upon by a gas pressure for a backwashing operation to dispense the quantity of cleaned fluid at least partially from said clean fluid chamber and having a movable separation element between said clean fluid chamber and said gas chamber, movement of said separation element by the gas pressure dispensing the quantity of the cleaned fluid for the backwashing operation;
• and
• an overflow space being in fluid communication with said clean fluid chamber through a filling hole in a wall of said backwashing guide during the filtering operation, said filling hole having a graduated diameter forming a narrowing inlet opening directed toward said clean fluid chamber and filling said clean fluid chamber while said separation element moves in a direction away from said filling hole with an increasing volume of said clean fluid chamber.