Study On Three-parameter Optical Shift Schedule And Control Method Of Construction Vehicle

Construction vehicles are widely used in economics of the country and construction of national defence, and playing an increasing role. It is the definite trend for construction vehicles to realize automatic shift in the future, which has an important meaning in alleviating the working strength of drivers, enhancing the productivity and working level, decreasing fuel consumption and improving the operating character of construction vehicles. Nowadays there is not a complete and special technique of automatic shift for construction vehicle. We usually use technique of automatic shift for automobiles. However, the main job of construction vehicles is working, and working pump will consume much power which can reach 60% at most. This is different from automobiles whose main job is steering, so it will make power performance and fuel economy lower if using the present theory of automatic shift.This Ph.D. dissertation are developed under the project named"Study on automatic transmission based on four parameters of construction vehicle"supported by DOCTOR Foundation project (No. 20020183003). And its main purpose is to improve the working and economical characters of construction vehicles, and emphases on studying the theory of automatic shift for construction vehicles. Besides, it will perform a deep and systemic study on the control method, simulation system and shifting quality. This dissertation can be divided into seven chapters.Chapter 1 Exordium. Based on a lot of reading and understanding of literature materials in and abroad, the background for choosing the subject and the purpose and meaning for realizing automatic shift were stated. Summarized the course, actuality, trend and practice in construction vehicles, and analyzed the problems and disadvantages of the study actuality of automatic shift in and abroad, the main study content was shown. Chapter 2 Analysis of driving system for construction vehicles. First, the composing and characters of driving system for construction vehicles was analyzed, and math model of driving system was established with modularization method. Second, with the present disadvantage of non-leading and much error for engine speed regulation models, a dynamic timing math model which is continuous leading and has a high imitating precision was established. This model settled a basement for the establishment of engine dynamic simulation model. Third, the common calculation methods and shortage of resistance of operation for construction vehicles were involved, and the relationship between resistance of operation and working pump pressure and driving force were also included in this chapter. The calculating equation for the portrait force of resistance of operation and working pump pressure was deduced. Based on this, the dynamic equations for driving and operation conditions were deduced respectively, which established a theory base for study and simulation control of automatic shift.Chapter 3 Study on automatic shift theory and control strategy for construction vehicles. Firstly, considering the fuel consumption rate of engine, the efficiency of torque converter and operation characters for construction vehicles, the best combination dynamical 3-parameter economical shift strategy for construction vehicles was advanced, then the shift points are deduced based on the common character curve of combination dynamical devices. Secondly, considering the non-steady and operation characters for construction vehicles, the dynamical 3-parameter economical shift strategy for construction vehicles was advanced, and the shift points are deduced by analytical method. Thirdly, the shift strategy considering power performance and fuel economy was made, then the coefficients of fuel economy and power performance are advanced to analysis the shift strategy. Finally, the improved BP network was used to perform control on automatic shift for construction vehicles.Chapter 4 Study on simulation of automatic shift system for construction vehicles. In order to validate the correctness and feasibility, the simulation system of automatic shift for construction vehicles was established based on the platform of SIMULINK and STATEFLOW of MATLAB simulation software. The simulation result showed that the average acceleration and velocity of dynamical shift strategy is higher than that of static shift strategy. In the same working condition and time, the farther vehicles can drive, the better the power character is. The best economical shift strategy can improve fuel economy greatly. Simulation showed the best dynamical shift strategy advanced in this paper is correct and feasible.Chapter 5 Study on control system of automatic shift. In this section we analyzed the design course of automatic shift control system specifically and emphasized on design of electronic control system. First, the whole design and method for electronic control system was advanced, and based on modularization design, the hardware and software design of electronic control system was introduced. Finally, anti-disturbing design was performed based on both hardware and software to ensure the stability and reliability in complicated environment, which made a good preparation for the experiment study in the next chapter, and established a base for the future installing vehicle experiment.Chapter 6 Experiment study. Firstly, Summarized the experiment system, including experiment purpose, experiment content, conformation and the main character parameters of test-bed and devices used in this experiment; Secondly emphasized on the best economy shift experiment, the best dynamic shift experiment and dynamical shift quality experiment; Finally, the experiment result was analyzed specifically. The correctness and feasibility of the dynamic three parameter best dynamical shift theory and combination dynamical three parameter best economical shift theory for construction vehicles advanced in this paper were validated. Besides, it is proved that shift quality can be improved greatly using best dynamic shift strategy.Chapter 7 Conclusion and expectation. The main study achievement, creation part and the existing problems in study were advanced, and the expectation for the future work was also put forward.The innovative research works in this Ph.D. dissertation is as follows:1. In order to decrease fuel consumption rate and improve the efficiency of transmission system, the optical economic shift theory of construction vehicle were put forward according to the characteristics of large power consumption by the working oil pump. According to the matching principle of engine and torque converter, by means of Matlab's high data procession, the universal characteristic curve were drawn of the combinatorial power under different working oil pump pressure, and then the optical economic shift theory curve and the solution method for the optical shift points were obtained, after that, the three-parameter optical shift schedule of the combinatorial were made. The experimental results show that the optical economic shift schedule presented in the dissertation can improve the fuel economy and save energy.2. In order to improve the power performance of construction vehicle and considering the dynamic characteristic of construction vehicle, the optical power shift theory of construction vehicle were put forward aimed at high acceleration(throttle opening, vehicle velocity and working oil pump pressure), and solving process for the shift points of three-parameter optical shift theory were deduced. After that, the three-parameter optical shift schedule of the combinatorial power was obtained. The experimental results show that the optical economic shift schedule presented in the dissertation can improve the power performance and shift quality.3. According to the trade-off between economy performance and power performance, the economy and power coefficients and its calculation formula were deduced, an the economy and power performance of the shift schedule were analysed, and then shift theory consideration to the economy performance and power performance, after that, the shift strategy were made.4. According to the reliability and the practicality, the control methods based on the BP neural network improved by Fletcher-Reeves conjugate gradient were put forward to control automatic shift of construction vehicle. The experimental results show that the automatic shift system of construction vehicle can be controlled preferably by intelligent control method, and can be shifted automatically according to the shift parameters.The research results in the dissertation give reference for the practicality of the automatic gearshift of construction vehicle.