| Most of modern engineering vehicles adopt automatic shift technology, which makes drivers free of frequent shift manipulation and concentrate on their main work. The automatic shift mode that hydraulic pressure controls shift enforce machines can result in shift impact of automatic transmission. If it were not severely controlled through making some measures, the shift impact would influence greatly drivers'mood and health, thus drivers would become more easily tired than manual shift. That violates the original intention that engineering vehicles adopt automatic shift technology. At the same time, violent shift impact would also make drivers so distractible that safety of drivers and vehicles would be threatened. Furthermore, life-span of accessories of drive system would get enormously shrink because of dynamic load resulting from shift impact. In order to eliminate shift impact, This paper combines with the project of National Foundation for Natural Sciences(No.59705005)"Research on Electronic Control for Saving Energy of Engineering Vehicle Hydrodynamic Mechanical Transmission System"and the doctor station fund project (No. 20020183003)of"Study on Automatic Shift Technology with Four-parameter of Engineering Vehicle"and the project of Education Ministry Foundation for backbone teacher"Research on Electronic Control Method for Improving the Dynamical and Economic Character of Engineering Vehicle Hydrodynamic Mechanical Transmission System", and takes 4D180 automatic transmission which is applied to ZL50 wheel loader as studying object analyzing abstractly value indexes of impact level and the causes of shift impact, then bringing forward improving approaches and control methods for shift quality. Finally, Research tentatively all of the above control methods through table experiment of automatic transmission shift quality. This paper includes such contents as follows:1. IntroductionOn the basis of referring to a great deal of external and internal vehicle automatic transmission information, the development, the applying status and the composing of automatic transmission are introduced, and the meaning, domestic and overseas researching actuality and developmental trend of automatic transmission shift quality are dissertated. Those prepare for the outspread for the studying question.2. Shift quality of automatic transmission and its influence factorValue methods and indexes of shift quality which have presently existed are expatiated and discussed. Subsequently, the causes of shift impact are analyzed and summarized as a whole.3. Engineering vehicle automatic transmission shift process analysisEquivalent dynamics model and corresponding mathematics model of 4D180 automatic transmission shift process are constructed. Both models are applied to analyze and study whole shift process in detail. Derived Mathematical expression of upshift and downshift to effectively analyze Dynamic Properties of shift process of automatic transmission and variational law of ATF pressure which greatly impact on shift quality.4. Control methods of engineering vehicle automatic transmission shift qualityIn the section, what are introduced is that Improving approaches of shift quality of control from enforce machines exterior, from improving design of enforce machines themselves and from powertrain system whole. Aiming at the 4D180 automatic transmission, what are brought forward is the methods of cushion control of installing accumulator or buffer valve, and of the timing control of adjusting enforce machine overlap time, and of electronic closed loop control whose aim is overcome the influence to shift quality owing to change of ATF mucous degree along with temperature and of friction components'clearance because of work surface wearing out. In addition, the method of changeable fuzzy control was adopted to control the high speed on-off valve in order to improve the shift quality in this work, and the results from simulation were compared with non-accumulator and accumulator circumstances in MATLAB- SIMULINK and show that the character state space of the system can be changed by setting the different control parameter collections according to the different phases of the control curve of the shift quality ,which can reach aims of shortening shift time and improving shift quality in the shift course. Moreover, engine torque is controlled through adjusting engine throttle. At the same time, those improving approaches and control methods can be testified feasible in theory.5. Table experiment of engineering vehicle automatic transmission shift qualityExperiment of every control method of 4D180 automatic transmission shift quality is carried out on "engineering vehicle electronic control experiment table" which was set up by"211 Project".In this part, the realizations of software and hardware control system, the aim of experiment, the structure of automatic transmission experiment table and the main parameters of performance are summarized, and the instruments used in experiment and anti-jamming methods are introduced, and the reliability checking of measuring system is made, and demarcate of test table is expounded. Apparatuses and methods of measuring rotate speed, torque, ATF pressure are introduce. Industry control computer is adopted as measuring and controlling system of automatic transmission experiment table. Real time control technology of timing and interrupt is used. Real time control scheme of automatic transmission experiment table is set forth and adopting VxD programme as Windows real time processing technology.In course of experiment, adopting different control method in turn, change curves of ATF pressure of enforce machines along with time and of rotate speed of transmission output shaft along with time. At the same time, velocity curves, acceleration curves and impact level curves are derived. Based on these parameter curves, every control method of automatic transmission shift quality get analyzed, and analysis results show that all of adopted control methods of shift quality for 4D180 automatic transmission is correct, reasonable and feasible.6. Summary of the whole paper.The summary of the whole dissertation is given in chapter six. |
PDF Full Text Request