Patent ID: 8518274

Claim:
A method of operating a filter device, comprising the steps of: conveying unfiltered fluid to be filtered into a filter inlet of a filter housing having a plurality of filter elements received in the filter housing; passing the unfiltered fluid through element input openings and into inner filter cavities of the filter elements in filter positions and through those filter elements to produce filtered fluid on exteriors of those filter elements; conveying the filtered fluid to and through a filter outlet in the filter housing to discharge the filtered fluid; placing at least one of the filter elements into a backflushing position while unfiltered fluid continues to flow through an element input opening thereof and into an inner filter cavity thereof; moving a movable backflushing arm by a drive to an end-side discharge opening longitudinally opposite the element input opening of the filter element in the backflushing position; moving a laterally extending blocking valve plate by the drive with the backwashing arm into alignment with the element input opening of the filter element in the backflushing position by being connected to the backflushing arm; quickly moving the blocking valve plate by a fluid operated piston with a piston extending perpendicular to the lateral extent of the valve plate from an open position spaced from the element input opening of the filter element in the backflushing position allowing unfiltered fluid to flow therein to a blocking position closing a fluid connection between the filter inlet and the inner filter cavity at the element input opening at least one of at a start of backflushing and during backflushing to create a hydraulic shock on the filter element in the backflushing position and to produce a feeding effect increasing removal of dirt thereon; and discharging dirty fluid from the end-side discharge opening of the filter element in the backflushing position during backflushing.