Limiting device for limiting filter

The limiting device comprises a metal cylinder, a protruding block is fixedly connected to the middle of the upper end of the metal cylinder, a threaded rod is fixedly connected to the upper end of the protruding block, tooth grooves are formed in the two sides of the threaded rod, deep grooves are formed in the two sides of the upper end of the protruding block, and the protruding block is fixedly connected with the threaded rod. A limiting piece is inserted into the deep groove, clamping pieces are fixedly connected to the two sides of the limiting piece, the limiting piece comprises a limiting piece, a limiting vertical strip is fixedly connected to the lower end of the limiting piece, and a limiting transverse strip is fixedly connected to the middle of the upper end of the limiting piece. The two limiting pieces are fixed to the two sides of the upper end of the protruding block respectively, the split type arrangement enables the whole limiting pieces to be fixed to the two sides of the threaded rod res