NEW STRUCTURE OF ROOTS BLOWER OR ROOTS VACUUM PUMP WITH A MULTI-LOBES IMPELLER AND A REVERSE FLOW UNIT

摘要

This invention relates to a new structure of Roots blower or Roots vacuum pump with a multi-lobes impeller and a reverse flow unit, the lobes of the impeller having a top width and according with the following equation: gamma 1 >/= alpha - beta 1 + epsilon 1, gamma 2 >/= alpha - beta 1 + epsilon 1 and theta >/= gamma 1 + mu + gamma 2. The intaking gas of the reverse flow, the lower pressure entering gas and the higher pressure discharging gas are separated from each other and are not interference with each other, thereby reducing the noise and increasing the cooling efficiency. The lobes are provided with labyrinth recesses on its top along its wide direction, resulting in lower radial leakage of the gas and more receiving of particles in the air without wearing between lobes and the surface of the housing.