| Hydraulic,mechanical continuously variable transmission,referred to as HMCVT.Based on the power splitting principle,the mechanical power and the hydraulic power are transmitted in parallel,and finally,an efficient stepless shifting is realised.The planetary gear mechanism plays a vital role in its design.Therefore,it is especially crucial for the design and optimisation of planetary gear mechanisms.Based on the principle of HMCVT transmission scheme,the design and analysis of three-row parallel planetary gear mechanism are carried out.Under the specific space conditions,the planetary gear parameters are designed and analyzed.The statics and dynamics are analyzed.The main contents and conclusions are as follows:(1)According to the principle of the transmission scheme of HMCVT finally determined by the subject,combined with the qualified conditions of the manufacturer,the design requirements are proposed.At the same time,the speed ratio,torque characteristics and power characteristics of the planetary gear mechanism are analyzed in the gear ratio determined under the condition that the displacement ratio is continuously changed.The final calculation results show that the hydraulic mechanical continuously variable transmission can realize the characteristics of stepless speed change under this principle scheme by calculating the speed characteristics.At the same time,according to the actual transmission condition of the tractor,it is proposed that the input torque is pushing the torque characteristic of each part of the three-row parallel planetary gear mechanism,and the influence of the ground adhesion is reversed from the output torque to each of the three rows of parallel planetary gear mechanisms.The method of torque characteristics provides a theoretical basis for the strength design of the hydraulic,mechanical continuously variable transmission.Finally,the power characteristic calculation is proposed.When considering the transmission power of the bus mechanism,it is necessary to consider the output power of the hydraulic component.(2)In order to design a planetary gear mechanism that meets both the error range of the planetary row characteristic parameters and the necessary conditions of the planetary gear mechanism,the analysis model of the three-row parallel planetary gear mechanism is established and verified.Mainly through Kisssoft’s intelligent solution,the planetary gear objective function is set by constraints,and all solutions in the gear ratio error range are obtained.Then compare the target function size of each scheme and choose the optimal set of solutions.Finally,the accurate calculation ability of Kisssoft in planetary gear design was verified,which paved the way for subsequent optimization design.(3)Find the objective function of the planetary gear mechanism optimization to further optimize the planetary gear mechanism.Mainly through the sliding rate equalization and flash temperature curve equalization analysis in each planetary gear mechanism,the gear parameters are further optimized,and the displacement coefficient is optimized to achieve a balanced design between the two.In general,the gear’s anti-wear and anti-adhesive ability are improved,and the overall performance of the gearbox is changed.(4)In order to verify the reliability of the model,Kisssoft and finite element analysis software were used to check the strength of the overall model of the system,and finally,the feasibility of the model was obtained.(5)Analysis of transmission error and contact stress of the sun gear and the planetary gear.The shape of the transmission error is improved by the shape modification design,and the noise and vibration of the planetary gear mechanism transmission are further optimized. |
