Patent ID: 8409429

Claim:
Filter device for filtering a fluid medium containing solids, comprising a backflushing filter and a flushing line, through which fluid backflushed during a backflushing phase from the backflushing filter can be supplied to a further treatment mechanism, wherein the further treatment mechanism comprises at least one of a sedimentation device and a solids separator, wherein the backflushing filter has a coarse dirt outlet which is connected to the flushing line at a mouth of the coarse dirt outlet so that coarse dirt which has arrived through the coarse dirt outlet into the flushing line can be supplied to the further treatment mechanism together with the backflushed fluid during the backflushing phase and which coarse dirt outlet is constructed to enable discharging coarse dirt from the backflushing filter into the flushing line during a filtering phase of the backflushing filter, wherein the backflushing filter has, in addition to the coarse dirt outlet, a further outlet to which the flushing line is connected, wherein the flushing line has a discharge valve, which is arranged downstream of the mouth of the coarse dirt outlet in the flushing line and upstream of the further treatment device, wherein the coarse dirt outlet has a coarse dirt valve, which is arranged upstream of the mouth of the coarse dirt outlet, for closing the coarse dirt outlet during the backflushing phase, wherein the filter device comprises a sensor for detecting a filling level of the coarse dirt in a coarse dirt collecting chamber in the coarse dirt outlet and/or in the flushing line and for initiating a backflushing phase of the backflushing filter if a predetermined maximum filling level of the coarse dirt is detected by the sensor.