Central tube component of filter element and manufacturing method thereof

A central tube assembly for a filter cartridge, comprising:

• a first half-tube, the first half-tube having a first flow passage extending in an axial direction of the first half-tube, an end of the first half-tube having a first water inlet communicated with the first flow passage, a side wall of the first half-tube having a water output hole communicated with the first flow passage;
• a filtering membrane, the filtering membrane having a first side formed as a raw-water side and a second side formed as a produced-water side, the filtering membrane being bent towards the raw-waterside to form a first membrane layer and a second membrane layer, the first half-tube being disposed between the first membrane layer and the second membrane layer and adjacent to a bending position;
• wherein at least one of a surface of the first half-tube and a surface of the second half-tube is provided with a reinforcing rib, in which the surface of the first half-tube is arranged opposite to the surface of the second half-tube, and the reinforcing rib abuts against the filtering membrane;
• an input-water filtering net, the input-water filtering net being connected with the first half-tube, and disposed between the first membrane layer and the second membrane layer to define a waste water passage between the first membrane layer and the second membrane layer;
• a second half-tube, the second half-tube being disposed outside of a bending of the filtering membrane and adjacent to the first half-tube, the second half-tube having a second flow passage extending in an axial direction of the second half-tube, a side wall of the second half-tube having a water input hole communicated with the second flow passage, an end of the second half-tube having a first water outlet communicated with the second flow passage;
• and
• a produced-water filtering net, the produced-water filtering net being connected with the second half-tube, the produced-water filtering net, the first membrane layer and the second membrane layer being coiled on the first half-tube and the second half-tube in a same direction, wherein the first half-tube is fixed with the second half-tube, the produced-water filtering net being disposed between the first membrane layer and the second half-tube to define a purified water passage between the first membrane layer and the second half-tube, the purified water passage being communicated with the water input hole
• an upper-end cover, the upper-end cover having a second water inlet communicated with the first water inlet and a second water outlet communicated with the first water outlet, the upper-end cover being fitted over upper ends of the first half-tube and the second half-tube, the upper-end cover tightly pressing an upper end of the filtering membrane to seal an upper end of the central tube assembly;
• and a lower-end cover, the lower-end cover being fitted over lower ends of the first half-tube and the second half-tube, the lower-end cover tightly pressing a lower end of the filtering membrane to seal a lower end of the central tube assembly.