Patent ID: 7055699

Claim:
A filtering device, comprising: a cylindrical filter element; a housing which surrounds and seals the filter element; a raw water inlet for supplying pressurized raw water to a raw water chamber located on an inner side of the filter; an outlet for discharging filtrate from a filtrate chamber located on an outer side of the filter element; a suction nozzle disposed within the raw water chamber and having an opening facing an inner surface of the filter element; a cleansing water discharge section connected to the suction nozzle, which discharges cleansing water drawn into the raw water chamber via the suction nozzle to outside the raw water chamber; a suction control device for controlling the cleansing water discharge device to thereby control suction of the cleansing water via the suction nozzle; a suction nozzle shifting device for moving the suction nozzle along the inner surface of the filter element; a backwash nozzle disposed within the filtrate chamber in a position opposing the suction nozzle for injecting backwash water; a backwash water supply device for pressurizing backwash water and supplying the pressurized backwash water to the backwash nozzle; and a backwash nozzle shifting device for moving the backwash nozzle in synchronization with the suction nozzle, wherein the suction nozzle and the backwash nozzle are moved in synchronization with one another along axial and circumferential directions of the filter.