In order to probe theoretically the radius variation ratio principle of the hypocycloid single-screw hydraulic machinery, this paper analyzed the relationship between the figuration movement and the joggle movement of shaft-housing pairs, described how the radius variation ratio to influence the line-stye of shaft-housing pairs. The results show that: when the radius variation ratio is a comparatively bigger value, the isometric profiles is not very good,so the turning zone is frayed rapidly.On the other hand, when the radius variation ratio is very small, such as 0.2, the floating contact area centralizes to the midpoint, the midpoint zone will be frayed rapidly. So the conclusion is that the finer radius variation ratio should be close to 1 under the circumstances that the isometric profiles has no drape on it.

single-screw hydraulic machinery;line style, motion analysis, hypocycloid

为从理论上确立短幅内摆线型单螺杆式水力机械变幅系数的选取原则,通过分析螺杆-衬套副的形成运动与啮合运动之间的关系,研究了不同变幅系数对单螺杆式水力机械接触状况及密封性能的影响。研究结果表明：变幅系数过大,则等距曲线容易打扣,使密封性能下降;变幅系数过小,则定子上流动接触点可到达的区域向定子内凸中点集中,使定子内凸中点处磨损严重。因此,变幅系数的选取原则是：

在保证定子等距线不打扣的情况下,尽量接近1。

单螺杆水力机械, 线型, 运动分析, 内摆线