Research On Torque Converter With Impeller Clutch And Its Aplication To Loader

As a kind of multifunctional earthmoving machineries,wheel loader is widely applied in modern engineering construction.The power of wheel loader comes from engine.In addition to a small part of the engine power is used to drive the cooling fan and other accessories,most of the remaining engine power is divided into two parts.Part of the remaining engine power is used to drive the hydraulic system of the working device,and the other part of the power through the hydrodynamic mechanical transmission system to the wheel is used to drive the wheel loader.The matching performance between torque converter and engine determines the power performance,economy,and working efficiency of wheel loader.However,the performance of torque converter used on wheel loader is simplex at present,and cannot satisfy the requirements of ideal matching performance under both typical running and shovel loading conditions simultaneously.In order to solve the problem that the output power of engine can be distributed between hydrodynamic mechanical transmission system and working device hydraulic system dynamically and reasonably,this paper takes a 7-ton loader as the research object,a torque converter with impeller clutch is designed and its characteristic's effect on the performance of wheel loader is researched.The main contents and conclusions are as follows.(1)The torque converter with impeller clutch is designed to solve the problem that the output power of engine is distributed dynamically and reasonably.Similar design method is adopted to design the torus of torque converter whose effective diameter is 370 mm.The conformal mapping method is adopted to design the blades of pump,turbine and stator of torque converter.The impeller clutch and other auxiliary parts are designed based on the structure of torque converter.The whole structure of torque converter with impeller clutch is designed finally.The CFD method is used to analyze the original characteristics of torque converter and the pressure of lateral cavity.Through building the force equilibrium equation of impeller clutch,the torque characteristics of impeller clutch under different control pressure are analyzed,the relationship among control pressure,rotational speed ratio and slip ratio is set up.Then the cooperating performance between torque converter and impeller clutch is calculated.(2)The working condition of each stage of wheel loader's V-shaped shovel loading operation cycle is analyzed in detail based on the power transmission system and the parameters of a 7-ton loader.According to the performance of engine and torque converter with impeller,the mathematical models are established,and the common work input and output characteristics under running condition and shovel loading condition are obtained by the static variable power matching calculation.The power performance,economy and shovel loading efficiency of loader are analyzed according to the common work characteristics.The analysis results show that the power distribution between hydrodynamic mechanical transmission system and working device hydraulic system is regulated and the power utilization of engine is improved under the action of impeller clutch.The response speed of working device is sped up and the efficiency of shovel loading is improved by using the impeller clutch.The slippage condition of tire is reduced by the use of impeller clutch when the loader works on the road with a low frictional coefficient.(3)The variable power control system is designed and the variable power control method is proposed to make the slip ratio of impeller clutch stepless and adjustable.The dynamic matching simulation model in view of the variable power control system is established by using the MATLAB/Simulink software.The input signal of the dynamic matching simulation model and other related datas are acquired by testing the 7-ton wheel loader's V-shaped shovel loading operation cycle.The matching performance between engine and torque converter with impeller clutch under a V-shaped shovel loading operation cycle is simulated and analyzed by using the simulation model.The simulation results which includes the power of engine,the input power of impeller,the output power of turbine,the consumed power of working device hydraulic system,the fuel consumption and other performance parameters are compared and analyzed with the original datas.The research shows that the problem of reasonable distribution of engine power is solved effectively,and the performance of the wheel loader under shovel loading condition is improved obviously by the torque converter with impeller clutch and its variable power control system.