source four axial inlet channels are provided in different radial angle positions of the central rotor 21 and four circumferential gas inlet grooves 211 212 213 214 are provided in the central rotor 21 the gas inlet grooves are circumferential annular grooves provided in the outer wall of the central rotor 21 in turn one end of each axial inlet channel is respectively communicated with the gas inlet groove through one radial hole and the other end is communicated with one inlet branch 711 in the annular inner walls of the first the second the third and the fourth chambers 31 32 33 34 are formed one inlet channel communicated with the chambers such as the inlet channel 330 in the third chamber 33 as shown in fig3 each the inlet branch is communicated with the first the second the third and the fourth chambers 31 32 33 34 through the inlet channel and connected to the sealed balancing disk 1 through a pipe joint respectively in the axial direction the middle sleeve 22 is provided with four vents 221 222 223 224 in turn one end of which is communicated with the four gas inlet grooves 211 212 213 214 respectively and the other end of which is communicated with the first the second the third and the fourth radial inlet channels 231 232 233 234 respectively the first and the second emptying tubes 61 62 have a same structure as shown in fig1 the first emptying tube 62 includes an axial emptying section 215 and a radial emptying section 216 located in the central rotor 21 a radial emptying section 225 located in the central sleeve 22 and a radial emptying section 235 located in the outer stator 23 the radial emptying section.