Design And Analyse For Upright 3-cylinder Motorcycle Engine Electronic Control System

This paper takes the LJ750 motorcycle engine developed by the Luoyang Northern Enterprises Group Co. Ltd as the research target, makes research and development on the LJ750 motorcycle engine Electronic Control System. The article completes the developing design of the electronic control system basing on the LJ750 engine structure and performance, which includes sensors'model selecting, ECU (Electronic Control Unit) design and operators'model selecting. the key part of the electronic control system is ECU utilizing PIC16F877 singlechip as the executor. The design for the key part ECU contains hardware and software design. The hardware design covers the design for input signal processing circuit and executor drive circuit. The software design analyze the software control strategy from the four aspects of engine work modes, fuel injection, ignition and idle speed control.This paper divides the engine work modes into malfunction mode, starting mode, overspeeding mode, speed shifting mode, decelerating and fuel cutting mode, idle mode and MAP mode, ECU judges the engine work mode through sensors'signals and operates the relevant controls of fuel injection time, ignition and idle speed. The fuel injection mode adopts intake path multi-point sequence injection, fuel injection control mode is oxygen sensor close-loop control, the fuel injection mount calculation uses the open degree-speed method, the basic injection time should be searched through the 3D MAP and modified under certain work condition to get the final fuel injection time; the ignition control is to control the ignition coil close angle and ignition advance angle by CCP1 and CCP2, the ignition advance angle calculation uses the method of getting the basic ignition advance angle and modifying it under certain work condition to get the final ignition advance angle; to speed up starting and engine warming, the idle control adopts open-loop method to adjust the side air path, under the idle work condition after engine warming, it uses close-loop control based on fuzzy control. For the motorcycle engine work condition is bad with interferential sources which may lead to"out of control"and"out of work"during program executing, this paper utilize hardware anti-jamming design and software anti-jamming design for the electronic control system by analyzing the factors for interferential sources.