Optimization Design Based on I-GA and Simulation Test Verification of 5-Stage Hydraulic Mechanical Continuously Variable Transmission Used for Tractor

To improve the characteristics of a tractor power transmission system, make the transmission system not only meet the geometric principle but also meet the working speed requirements of the tractor, realize the continuous adjustment of the speed ratio, and solve the power interruption caused by the change of speed ratio. This paper not only proposes a new type of five-stage hydraulic mechanical continuously variable transmission (HMCVT), but also proposes a geometric design method based on I-GA. In this paper, the intersection position of each working section is introduced in the optimization design process, and six wet clutches, one brake and two planetary rows are used to achieve a flexible geometric design. The results show that the HMCVT proposed in this paper can effectively match the required speed of the tractor. After optimization, the transmission ratio characteristics are consistent with the target characteristics (the average error is about 3.27% and the common ratio is about 1.81); the simulation results based on Simulation X are highly consistent with the theoretical design values (the MAPE of 36 simulation experiments is about 0.72%); and the maximum speed of the tractor is 41.62 km/h. The proposed HMCVT design scheme and optimization design method provide a direct basis for the research and development of the composite power transmission system of tractors or other vehicles and agricultural machinery.