Filtering device and cleaning unit for removing dirt particles from a filter element of a filtering device

A cleaning unit for removing dirt particles and contaminants from a filter element of a filtering device, the cleaning unit comprising:

• a cleaning head with at least one scraper member for detaching dirt particles from the filter element, wherein said cleaning head and said filter element are movable relative to each other and can be brought into contact with each other at least temporarily;
• a servomechanism coupled to the at least one scraper member, the servomechanism configured to press the scraper member onto a surface of the filter element, the servomechanism having at least one bellows cylinder comprising:
• a foot section having at least one opening for a fluid-channelling connection to a pressure source,
• a head section which can be moved along an adjustment path relative to the foot section,
• a deformable bellows element which is sealingly connected to the foot section and to the head section, and
• a pressure chamber of variable volume which is adapted to move the head section relative to the foot section depending on the pressure prevailing in the pressure chamber;
• and
• a supply channel which is connectable to the pressure source.

A filtering device for removing dirt particles and contaminants from a plastic melt, the filtering device comprising:

• a housing having a filter chamber configured to receive plastic melt therein, and a dirt outlet for discharging dirt particles from the housing;
• a filter element arranged in the filter chamber and through which a stream of plastic melt can be channelled, the filter element being configured to retain any dirt particles contained in the stream of plastic melt;
• a cleaning unit for cleaning the filter element of dirt particles retained by the filter element, said cleaning unit having a cleaning head with at least one scraper member for detaching dirt particles from the filter element, wherein said cleaning head and said filter element are movable relative to each other and can be brought into contact with each other at least temporarily;
• and
• a servomechanism coupled to the at least one scraper member and configured to press the at least one scraper member onto a surface of the filter element, the servomechanism having at least one bellows cylinder comprising:
• a foot section having at least one opening for a fluid-channelling connection to a pressure source,
• a head section configured to move along an adjustment path relative to the foot section,
• a deformable bellows element which is sealingly connected to the foot section and to the head section, and
• a pressure chamber of variable volume which is configured to move the head section relative to the foot section depending on the pressure prevailing in the pressure chamber,
• wherein the cleaning unit includes at least one inner shaft member with receptacles for the at least one bellows cylinder and an outer knife drum which forms an outer surface of the cleaning unit and which separates the at least one bellows cylinder fluid-sealingly from the plastic melt to be cleaned.