Studies And Development On Unit Pump Control System Of Diesel Engine

Studies and Development on Unit Pump Control System of Diesel EngineFAW choose to develop unit pump control system for diesel engine in order to meet the demands of Euro 3 automotive diesel engine exhaust emissions standard and fuel economy on the basis of maturity and adaptability for fuel quality on unit pump hydraulic system. As same time, self- developing diesel engine control system answers for China government demand on automotive industry, that is researching automotive control system, mastering essential control technique, founding automotive control system production base.This thesis is development of unit pump control system for diesel engine in above background according to the project"embedded software platform for automotive control system"financially supported by the National Committee of Science and Technology and the project"Engine ECU development"financially supported by FAW Group. After entering thesis, I go though the whole process from system configuration, ECU software and hardware development to control system optimizing and calibration in six years.This thesis presents the research results on the issue of key and common technique for unit pump control and production in diesel engine. First, general control platform and hardware design principle are provided on the analysis of control aim and principle of unit pump control system. Secondly, real-time operating system is designed and applied to the unit pump control software development. Thirdly, control strategies and arithmetic of fuel management and injection control are completed according to analysis of steady and transient engine running situation. Fourthly, production functionalities are implemented including diagnosis functions, communication functions, calibration functions and ECU End of Line functions. And then, developing and management methods are presented based on practice in whole process. Finally, the developed platform control system is applied to unit pump diesel engines after calibration and achieves the aim of industrialization and in-market. The main achievements of this research can be detailed in the following:The embedded platform development method is the advanced developing concept in international company. The platform is adopted which is divided into application software layer, hardware layer, hardware driver layer and operating system layer in this thesis. This concept helps to avoiding coupling software development with hardware development, to reducing development difficulties, to enhancing production quality, to transplanting hardware system and to adding new control function easily.Driven by platform concept, hardware is designed according to demand of ECU working environment and software size. Hardware circuit consists of regular input and output circuit, communication circuit, battery management and reset circuit, injection driver circuit. The specific solenoid driver control integrated chip is designed on the characteristic analysis of electromagnetic valve so that this design can meet with cost control in mass production and reliability demand.Driven by platform concept, embedded real-time operating system is designed which consists of operating system kernel OS and communication module. OS which is OSEK standard-compliant realizes tasks management of basic tasks and extended, scheduling method of full preemptive, non-preemptive and mixed preemptive, task synchronization method of events and resources, alarm cyclic handling mechanism, ceiling priority mechanism for resolving priority reverse, two interrupt handling mechanism. So OS achieved the aim of deep-embedded, small size and high real-time. Communication module which is OSEK standard-compliant realizes internal communication management, message send and receive through different object, message receive through queue and non-queue, filtering mechanism for receiving message. The embedded real-time operating system is the important factor that impacts on individual development of software and hardware.During the control strategies research for unit pump system, the engine is controlled not only for normal running condition, but also for system reprogramming and after-run store in every drive cycle from power on to power down by the means of proper working mode identification. According to traits of diesel engine and modular design concept, fuel management strategies consist of starting control, idling control, drivability control, cruise control, power take-off control, vehicle speed limiting, engine speed limiting, fuel quantity limiting, engine brake, transition among different above conditions and other controllers demand in the vehicle. This thesis focuses on start control strategies, idle control arithmetic for in neutral and different shifts, active surge damping function, cut-off and refueling function during driving, injection fuel arbitration method for all running conditions and control strategies for cylinder-balancing. Experiments results show that the design is reasonable and effective because of good steady and transient control effect.This thesis captures the five important strategies for mechanical timing control to ensure the accuracy and nicety of injection control in unit pump. Firstly four different engine mechanical phases are identified by software configuration. Secondly, engine mechanical synchronization is identified as soon as possible to ensure engine rapid start and injection accuracy. Thirdly, backup synchronization strategy is started if one of speed sensor and phase sensor is error. Fourthly, redundant start procedure according to individual speed sensor is realized by injection and evaluation algorithms. The last, injection accuracy achieves 0.0234 degree by the means of injection angle clock and dynamic interrupt.Aim to complexity and high safety of diesel engine control, ECU on-board diagnosis function is built on the analysis of control system principle which includes fault detection and handling of typical sensors, actuators and hardware sources by the means of fault self-diagnosis. When the fault occurs, ECU can control the warning lamp, torque reduction and shutdown according to fault severity levels. The experimental results show that it's effective method to ensure control system safety with fault self-diagnosis function.The diagnostic communication and management function which is for service supplies the window of detecting control system status and fault for serviceman. This function realizes communication between ECU and service tool, setting up safety accessing mechanism, reading ECU identification information, reading engine running information, reading engine fault information and frozen frame, storing engine fault, clearing engine fault and adjusting engine and pump characteristic during assemble line.This thesis realizes the specific interface of EOL (End Of Line), which communicates and flashes application code and calibration data with EOL tool. This interface ensures not only matching the application code and calibration data with corresponding engine and vehicle, but also flashing correctness of application code and calibration data.This thesis presents the core techniques for diesel engine control, breaks through the technique barricade from abroad during six-year development. Self-developed unit pump control system reaches the similar system level and meets with Euro 3 exhaust emissions standard. The common rail control system which is calibrating in beginning phase is developed based on this unit pump control platform.