Design of Pitch Curve of Internal-Curved Planet Gear Pump Strain in Type N-G-W Based on Three-Order Ellipse

In N-G-W type non-circular planetary gear strain, the planetary gear is meshed both with the center wheel and the inner gear ring. The parameters which the design of the planetary wheel system required can be received according to the three-order elliptic equation which consist of continuous smooth closed curves as the pitch curve equation of the center wheel, and on the basis of planetary gear teeths relation, the closed condition of the pitch curve and the teeth uniformly distributed in the curve. This paper studied the design process of the pitch curve on an N-G-W type internal-curve planet gear pump by a practical example.