Electronic Pneumatic Shift System And Its Malfunction Diagnosis

With the development of modern society and the improvement of living standards, the automobile industry has been developed fleetly, and people demand more about the functions and capabilities of vehicles. At present, most city buses adopt the postposition engine and manual mechanical transmission. When the vehicles run, drivers must do the manipulation of start, gearshift and stop repeatedly and frequently, so the working intensity is very large and the comfort capability and fuel economy is bad. Also there are serious latent troubles of traffic accident. Using the research experience for reference in home and abroad,and according to our national actual situation, we developed an Electronic Pneumatic Shift System that has a good cost performance ratio.Based on the original manual gear box, the mechanical machine is redesigned and the manual gear box is replaced by the electronic transmission. The system takes the ECU as the control kernel and utilizes the method of the Electronic Pneumatic Shift to complete the prospective shift operation. This system can not only maintain simple structure and high efficiency, but also have high manufacture facility and high performance-price proportion. So this project has important academic significance and applied value.This thesis introduces the history, current situation and developing trend of the transmission system. The work theories of transmission, clutch and the synchronization machine are introduced firstly and then shift processes are discussed in details. Subsequently, the blue print of whole system with the structural design of the control and the implement unit are expounded. Based on the mechanical structure, this thesis has also expoudsed its hardware circuit design,including signal circuit, electromagnetic valve control circuit, the main control and the implement unit and other circuit. This thesis also expouds the diagnosis to the possible malfunction of the whole system, and bring forward the solutions. The application of CAN-Bus is also introduced, including the node hardware design and the frame of the communication protocol. At the same time the system software based on the the hardware is also designed. Finally the hardware and software are testd to make sure the whole system can work smoothly.