Patent ID: 8757394

Claim:
A filter element comprising: a flat filter medium sheet of a non-woven filter material having a first end section at a first edge of said sheet and having a terminal edge; a second end section at an opposing second end of said sheet and having a terminal edge; wherein said second end section overlays upon said first end section; a sheathing arranged on said end sections and enclosing over said terminal edges, said sheathing compressing said end sections together; wherein said end sections and said sheathing are made of the same non-woven filter material; wherein said sheathing is a flexible porous nonwoven filter material suitable for ultrasonic welding or laser welding; wherein said sheathing material is any of: a meltable material or a material with a meltable coating; wherein said sheathing is secured onto said end sections and terminal edges; wherein said sheathing and said end sections are secured together by ultrasonic welding or laser welding; wherein said sheathing includes a first fold leg; and and second fold leg; wherein said end sections are positioned between and compressed together by said two fold legs; wherein said fold legs and end sections are securely fastened together; wherein said flat filter medium sheet includes a plurality spaced folds forming a zigzag folded filter medium; wherein said end sections and said sheathing fold legs are moreover connected by gluing.