Abstract: A dust bag comprises a filter bag consisting of a filter material. In a first wall portion of the filter bag, an inlet opening is provided through which the air flow to be cleaned gets into the filter bag. On the inner surface of the wall portion opposite the inlet opening, there lies a protective layer of a resistant material of great tensile strength. This protective layer extends as a strip through the filter bag and prevents damage to the inner surface of the filter bag caused by particles striking the same.

Abstract: The filter device (10), provided for the filtration of fluids, comprises two interconnected material structures (14,16) forming a filter unit (12). The two material structures (14,16) are mechanically stable, at least one of the two material structures (14,16) being elastically deformable. The two material structures (14,16) are connected to each other at opposite connecting sites, with one (16) of the material structures forming an arch between the connecting sites. This arch has been generated by elastic deformation of the respective material structure (16) so that this material structure (16) is mechanically biased. A stretching movement of this material structure (16) is prevented by the connection of this material structure (16) to the other material structure (14) which in turn is of substantially plane configuration and is tensioned.

Abstract: The filter element (10) includes a filter material layer (12) being held and supported by a support material layer (14). The support material layer (14) can be folded in zig-zag manner and has bending regions (16, 17) with folding portions (18) therebetween. The support material layer (14) has the region of its folding portions (18) provided with deformations (20) projecting from the planes of the folding portions (18). The filter material layer (12) is supported by the support material layer (14) through the boundary edges of the deformations (20).