The invention discloses a treatment casing with an adjustable grooving width of a centrifugal
air compressor. The casing comprises a self-circulation casing channel formed in a
volute, and an adjustment device with the adjustable grooving width, wherein the adjustment device comprises a
hollow cylinder, a
cam structure and a spiral spring; the
hollow cylinder is arranged in a flow guide ring groove and moves along the flow guide ring groove; and the
cam structure comprises a
cam, a cam shaft and a sealing hollow structure arranged on the upper part of the cam shaft, the interior of the sealing hollow structure is divided into two chambers, each chamber is connected with an air guide
pipe, and the other ends of the air guide pipes are connected to the different positions in the circumferential direction of the
volute. The cam shaft is pushed to rotate through the
pressure difference of the two chambers to drive the
hollow cylinder to move, so that a casing design that the width of a suction ring groove is adjusted with the working condition of the
air compressor. According to the technical scheme of the invention, compared with a self-circulation treatment casing with a fixed-width suction ring groove, the width of the suction ring groove can be adjusted, so that the stable
working range of the centrifugal
air compressor can be greatly expanded, and the pressure ratio and the adiabatic efficiency of a part of working conditions are increased.