Research On The Electronic Control System And The Control Strategy Of The Metal Pushing Belt CVT

The metal pushing belt CVT (continuously variable transmission) is a new type of ideal transmission for passenger car, which possesses many advantages of simple structure, easy operation, high efficiency, low fuel consumption, low air pollution, and so on. As an advanced technology to develop passenger car, it can meet the demands of developing passenger car and there will be a great developing potentiality and extensive market in China. This thesis mainly focuses on the development of the electronic control system and the control strategy of the metal pushing belt CVT.At the beginning the thesis reviews the development process of the metal pushing belt CVT technology and analyzes the current applications of this technology. In this paper the background and the necessity of this theme in science and practice are given. After reading many reference literatures, this thesis analyzes the features and mechanism of the metal pushing belt CVT. All achievements provide theory foundation for developing CVT control system. After analyzing the characteristics of the hydraulic system and its components, the thesis accordingly develops the hardware and software of the electronic control system for CVT. In order to achieve the drivability in transient state and the minimum fuel consumption in steady state of the vehicle, the matching law and the integrated control strategy of CVT and the engine are discussed in this thesis. Taking into account the complexity of CVT system, a fuzzy self-adaptive PID controller based on ratio feedback is introduced into the ratio control system and a fuzzy controller is introduced into the clamping force control system. Firstly the developed electronic control system of CVT is tested on the test-bed, and then it is implemented to the Fiat passenger car to test on the road. The test results of typical driving conditions show that the developed electronic control system and the control strategies can meet the demands of all driving conditions, and the system is applicable in practice.The creative work in this thesis is the first application of the fuzzy self-adaptive PID control strategy in CVT ratio control. It is the first time to equip the Fiat passenger car with self-developed electronic control system. It is also the first time that the CVT car abolishes the E/S/D model switch and the engine is controlled using the fuzzy control strategy.