Abstract: Aiming at the phenomena that working contours of matching teeth can intercross or separate each other under equality model of eccentric involute gear transmission and it should not take place in real gear transmission, a kind of inequality model of eccentric involute gear transmission without assumption error is presented according to the geometric meshing relationship between involute teeth contours of driving gear and driven gear. A complete numerical solution of inequality model is given by taking odd teeth gear transmission as an example. According to the numbers of different intersection generated between inner common tangent line and working contours of matching teeth of two gears, a searching algorithm of meshing points can process four kinds of situations when the driving gear drives the driven gear continuously at a random rotation angle, and produces correctly seven kinds of different meshing results of matching teeth. Computational results show that the intersection between the geometric center line and the inner common tangent line of two gears do not divide evenly the two lines, and the meshing points of the eccentric involute gear transmission are not always on the inner common tangent line, which has nothing to do with distance between shafts. When 5 000 coordinate points of involute working contours of benchmark tooth are determined to compute the inequality model, the coordinate control precision of searching meshing points can reach 0.001 millimetre and the angle error can reach 0.001 degree. Numerical solution may get precise rotation angle relationship between the driving gear and the driven gear, and may provide a reference for accurate analysis and optimization design of eccentric involute gear transmission.

Key words: CAD, Eccentric gear, Inequality model, Numerical computation