Multi-Objective Optimization of Design Parameters for Tractor Hydro-Mechanical Continuously Variable Transmissions

The design parameters of the transmission directly affect the vehicle's dynamics and fuel economy, due to the complexity of the tractor's working conditions and operating modes, the optimization of the transmission design parameters is more difficult. In this paper, an independently designed hydro-mechanical CVT transmission is taken as the research object, and the transmission design parameters are optimized based on the tractor's whole life-cycle speed usage rate, and the multi-objective genetic algorithm is used for optimization and solution. In this paper, the fuel consumption rate and hill climbing degree are taken as the optimization objective function, the parameters that have a greater influence on the optimization objectives are selected as the design variables, and the constraints are determined. A multi-objective genetic algorithm based on the Pareto optimality principle combined with experimental design is used to establish a multi-objective optimization model of the transmission device based on modeFrontier, and a global search for optimality is carried out, and a Pareto optimal solution is finally obtained. The results of the study find the optimal solution under the constraints, reflecting the conflicting characteristics between power and fuel economy. The design variables of the Pareto optimal solution obtained through optimization iterations based on the whole life cycle speed usage rate satisfy the matching requirements of the transmission well.