对渐开线叶型三叶罗茨风机的渐扩缝隙预进气结构进行了理论分析,并与普通结构的回流缝隙的差别进行了比较。给出了渐扩缝隙预进气结构的回流缝隙的理论值与实际值,计算出基元容积内的压力。生产实例表明,采用渐扩缝隙预进气结构,可以使三叶罗茨风机工作于几乎无回流冲击的理想状态,最后给出了渐扩缝隙起始位置选择的参考值。 The theoretical analysis of the pre-charge structure of involute leaf-type three-lobe Roots blower is carried out and compared with the difference of the backflow gap of common structure. The theoretical and actual values ​​of the backflow gap of gradually expanding gap pre-charge structure are given, and the pressure in the elementary volume is calculated. The production example shows that with the gradual gap pre-intake structure, the three-lobed Roots blower can work in an ideal condition with almost no back-flow impact. Finally, the reference value for selecting the starting position of the gradual gap gap is given.