| The metal pushing V-belt type continuously variable transmission (CVT) has the advantages of simple and compact structure, excellent performance and easy operation, which is an ideal transmission form for economical automobiles. Developing continuously variable transmission becomes a common standpoint in automatic transmission industry domestically. The electro-hydraulic control system is an important part for the whole continuously variable transmission, which is composed of TCU, hydraulic control system and mechanism. The key technologies of the electro-hydraulic control system include the following sections: 1, the design and test method for the hydraulic control system; 2, the test and development technology for proportional electromagnetic valve; 3, the design technology for speed ratio controller; 4, the technology of improving quality stability and coherence. This paper mainly focuses on the above-mentioned key technologies research, and acquires a few of achievement and innovation as follows.1) The whole hydraulic control system is divided into three sub-systems in terms of their unattached pressure levels, which are speed shifting mechanism control subsystem, clutch and torque converter control subsystem, and lubrication and cooling flux distribution subsystem. A complicated system is de-escalated, which is integrated based on the principle of function matching, and patterns of the hydraulic control module are manufactured. It is shown from the table-board test results that the primary performance indices such as steady pressure, dynamic pressure and transient flux of the hydraulic control module are adequate for the requirements of vehicle normally running. It is shown from the vehicle road test results that the hydraulic control module is adequate for the control requirements of clamping force, clutch and speed ratio. The influence of flux distribution result from the lubrication valve flux-pressure down characteristic is considered when designing the lubrication and cooling flux distribution subsystem. The lubrication and cooling flux distribution subsystem is optimized by means of reasonable optimal algorithm and it is shown from the test results that the optimized lubrication and cooling flux distribution subsystem could satisfy lubrication and cooling requirement of the whole CVT and local components under random working conditions. 2) The design method for CVT appropriative proportional valves is systemically studied. The structure and basic working principle of the valve are analyzed firstly, and then a dynamic model is set up by means of mechanism analysis. For the purpose of checking the validity of the modeling method, prototype workpieces of the valve is manufactured for comparison test, and its simulation result follows the experimental result quite well. An associated performance index is founded considering the response time, overshoot and saving energy, and several sensitive structural parameters are selected to adjust for deriving the optimal associated performance index. The optimization problem is solved by the genetic algorithm (GA) with necessary constraints. Finally, the properties of the optimized valves are compared with those of the prototype workpieces, and the results prove that the dynamic performance indexes of the optimized valves are much better than those of the prototype workpieces, which are more suitable for the automatic transmission.3) A new hybrid scheme of rough sets and support vector machine for quality classification is proposed based on the performance testing characteristics of the CVT clamping force control valve. The proposed quality classification method reduces the redundant feature parameters based on the rough sets theory. And then, based on the reduction result, the least squares support vector machine (LS-SVM) classifier is used to set up the quality classifier. The experiments show that the accordance rate of the proposed method is very accurate, which has great project application value in engineering.4) Aiming at the problem of the CVT speed ratio tracking fluctuation, the concept of generalized predictive control is introduced to the CVT speed ratio control. The artificial intelligent technology is introduced to design an intelligent predictive controller according to the requirements of engineering practices. The proposed controller utilizes the support vector machine (SVM) predictive model to forecast the future control effect; the introduction of this SVM predictive model improves the precision of forecast for its nonlinear behaviors. The optimal control is determined by using a simple chaos optimal algorithm (COA); the introduction of the chaos optimal algorithm improves the optimal control searching efficiency effectively and solves the problem of real-time in control process. It is shown from the bench test that the proposed control algorithm accomplishes the better steady and dynamic performances than those of general PID: the fluctuation reduces in static tracking; the overshoot and the transition time decrease obviously in step-response. 5) At last, fault diagnosis of the clamping force control system is explored with no additional hardware cost and no additional computation. The diagnosis strategy based on model is proposed, which realized fault diagnosis in terms of the errors of real-time measured signal and the outputs of the global and local diagnosis model. The experiment results indicated that the proposed self-diagnosis system of the clamping control system had higher precision and response speed, which is very important for CVT security protection initiatively.
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