According to the characteristics of objective function and planetary gear design, constraints can be divided into flexible constraints and rigid constraints. According to the transmission power and speed, according to the design experience, the approximate range of gear modulus, the selection range of tooth width and the minimum number of teeth to ensure that the undercutting does not occur are estimated as flexible constraints. The adjoining condition, tooth surface contact strength condition and tooth root bending strength condition of planetary gear are rigid constraints.
Flexible constraints:
The maximum modulus is
The minimum modulus is
The condition of no undercutting is
The upper limit of tooth width is
The lower limit of tooth width is
Rigid constraint refers to the geometric relationship and strength condition of planetary gear transmission system in normal work and meshing, which usually needs to be derived. Rigid constraints:
The adjoining condition of planetary gear is
Where, DAC is the diameter of the top circle of planetary gear teeth. Substituting the geometric meshing relationship and related parameters, the expression of proximity condition can be obtained as follows
The contact strength condition is
The root bending strength condition is
