泵用无困油无根切齿廓及其轴向超低恒脉动结构

针对外啮合齿轮泵困油现象和流量脉动大的结构性问题，基于渐开线齿轮的传动优势和成形原理，提出一种以重合度为1和齿廓根点位于基圆上为限制条件，齿数为唯一设计构造参数的无困油无根切齿廓的逆向构造方法。通过设计新的轴向双齿轮副结构，解决原有单一齿轮副流量脉动大的结构性问题。结果表明：逆向设计构造方法简单、精准；单副重合度为1可确保无困油现象；齿根点位于基圆上及变位滚切加工可确保无根切现象；单副0.375、双副0.094的恒流量脉动系数与齿数无关，利于在最小齿数为6时采用高容积利用系数0.35，且泵轻量化效果较好；双副轴向180°/齿数的错位间隔装配易于实现，综合重合度为2可确保传动平稳性等。

Tooth Profile Without Trapped-oil and Undercut for Pump and Its Axis Ultra-low and Constant Flow Ripple Structure

Focusing on solving the structural problems of trapped-oil phenomenon and large flow ripple in external gear pump, based on transmission advantage of involute gear and its forming principle, the contact ratio of 1 and root point of tooth profile located on base circle were used as the limiting conditions, and tooth number was the only design construction parameter, a reverse construction method of involute tooth profile without trapped-oil and undercut was proposed. A new axial double gear pair structure was designed to solve the structural problem of large flow pulsation of the original single gear pairs. The results show that the reverse design method is simple and accurate; when the contact ratio of single gear pair is 1, no trapped oil phenomenon can be ensured; when the root point of the tooth is located on the base circle and the modification hobbing is adopted, no root cutting phenomenon can be ensured; the constant flow ripple coefficients of single gear pair 0.375 and double gear pair 0.094 are independent of the teeth number, which is beneficial to adopt the high volume utilization coefficient 0.35 of six-tooth number gear, and the pump has better lightweight effect; double gear pairs assembled by axial dislocation and interval with 180° divided by tooth number is easy to achieve, and when the following axis comprehensive contact ratio equales to 2, the transmission stability can be ensured.