Optimization Of Loader Powertrain Based On The Typical Working Cycle

In order to release the performance of all components sufficiently and guarantee to satisfy the dynamic performance and economy of vehicle, the loader powertrain should be matched reasonably. Thence, the study of powertrain optimization was important for loader’s energy conservation. At present domestic research on Loader powertrain mainly optimized the diameter of torque converter and the ratio of drivetrain. Besides, the research of optimizing engine characteristic parameters was extremely few. Therefore, it was of great significance for the powertrain matching and the vehicle economy improving to obtain the power shunting of typical working cycle by acquiring and analyzing load spectrum data.This research aimed at solving the problem of ZL50 loader with high fuel consumption. The experimental test found that the vehicle matching speed was high, and engine operating point deviated from the optimum fuel distribution area, so it was necessary to optimize the powertrain. By reading the relevant literature, mastered loader powertrain matching processes and methods, as well as load spectrum data processing and statistical analysis method. The mathematical models of the engine, torque converter and other components were built with using spline interpolation, which could be used to calculate vehicle dynamics and traction performance.The load spectrum data was measured with loader V-type operations, including engine speed and torque, fuel consumption rate, transmission shaft speed and torque, vehicle speed, gear, hydraulic pump pressure, etc. The load spectrum signal was processed to remove outliers with using wavelet fractal dimension method. hydraulic system torque consumption shoveling different materials was obtained by analyzing the changing characteristics of hydraulic system pressure at the working cycle. Based on a short-stroke method, ZL50 wheel loader typical working cycle was constructed by using principal component analysis and cluster methods, then its effectiveness was verified through probability statistics analysis and models simulation.An inverse simulation model of wheel loader powertrain was constructed and a software was developed based on the MATLAB software. These working parameters of engine and hydraulic converter were simulated based on the typical operating cycle of loader. With comparison of simulated results and experimental data, the errors of engine speed within 94.04％and transmission ratio within 93.77％simulation time were less than 2%, and the error of fuel consumption based on the typical working cycle simulation was 4.7%. Therefore, the simulation model constructed by MATLAB software could simulate cycle operating parameters of powertrain accurately, which was also greatly helpful to further study the fuel economy of loader working cycle.One method was proposed to calibrate engine external characteristic according to the actual consumption of the hydraulic system based on the full-power matching method, focused on the ZL50 wheel loader, its electronic control system had been calibrated with the external characteristics. The results showed that the cycle fuel consumption reduced by 6％to 11％, and operating efficiency improved at some conditions after calibrating, which is helpful to multi-mode operation. Finally, according to the inverse model, the transmission ratio of drivetrain was optimized by using genetic algorithms so that the fuel consumption to a minimum.In conclusion, focused on the ZL50 wheel loader, powertrain model building, engine external characteristic calibrating, typical working cycle constructing, as well as transmission ratio optimizing was carried out. The methods of constructing wheel loader typical working cycle and calibrating engine external characteristic were proposed. The research results are conductive to advancing research on performance optimization for wheel loader and related engineering machinery.