The invention discloses an
impeller box which comprises a casing, a gear box located above the casing, a plurality of upper base ribs, lower base ribs, a plurality of water outlets and a plurality of water inlets. The ends of the inner sides of the plurality of upper base ribs form circles, the
radius of every circle is 1 / 6 to 1 / 3 of the inner
diameter of the casing, the height of every upper base rib is larger than 4mm, the height of every lower base rib is 2-4mm, an included angle between every two adjacent lower base ribs is larger than or equal to 10 degrees and smaller than or equal to 45 degrees, the sum of areas of upper openings of the plurality of water outlets is 1 / 3 to 2 / 3 of the area of the end face of a side wall of the casing 1, the sum of widths of water inlet ends of the plurality of water inlets is 1 / 3 to 1 / 2 of the length of an outer periphery of the casing, the sum of widths of water outlet ends of the plurality of water inlets is 1 / 3 to 1 / 2 of the length of an inner periphery of the casing, and the height of every water inlet exceeds 1 / 2 of the height of every blade. Compared with the prior art, the
impeller box can simultaneously reduce measurement errors of a water meter during large flow and small flow,
measurement precision of the water meter is improved, and the measuring span of the water meter is expanded.