Key Issues Of Engineering Vehicle Hydraulic Dynamics Theory Research And Test Rig Construction

On the ground of the questions existing in the field of tractive dynamics on mobile construction machinery, the thesis is intended to establish a new framework - a theoretical system of hydraulic dynamics and controls on mobile construction machinery. It profiles the key questions and studies their solutions in attempt to provide a reference for the researchers in the field of mobile construction machinery theory and its hydraulic dynamics and controls, so as to answer the questions in sizing general parameters and in control theory alike.The fundamental task for tractive dynamics on mobile construction machinery, under the limits by such comprehensive performance parameters as dynamism, fuel economy, productivity and so forth, is to study the working performances of the vehicle's tractive system with such parts as engine, power train, mobile mechanism and working devices, to establish a dynamics mode of the vehicle's tractive system and, then through analysis on that dynamical mode, a general tractive parameter-sizing theory in term of part average and a system input, output and dynamical control optimization theory, so as to realize the vehicle's highest comprehensive performances under dynamical loads outside and varying territories.Due to the inherent defects in process control performances of traditional mechanical and hydraulic transmissions on vehicles, tractive dynamics still can hardly work out an optimal performance control on vehicle's non-lineal tractive system under the condition of quick high fluctuation, even though a lot of researches have been undertaken on engine control, vehicle's mechanical speed-transformation control, working device's load ultimate and productivity control. The application of stepless, high efficient and fast adjusting hydraulic transmissions, under large range of speed-transformation, will be an effective measure to realize optimal performance control on the tractive system of tractive construction machines.By analyzing the tractive characteristics and performance parameters of mobile construction machines, the thesis classifies all the machines into two types: the tractive and the non-tractive. The former can be divided into cycling duty and continuous duty. Mechanical load is in a violent fluctuating, unstable and random process under cycling duty, while in a violent fluctuating, stable and random one under continuous duty, in both of which engine is fully, or mainly, loaded with tractive system. Without requirement on job quality, such vehicle's tractive system adopts self-adjusting speed control under constant and variable...