Design And Research On The Controller Of Medium Pressure Common Rail System For Diesel Engine

An diesel engine is one of the most important dynamic machines. It is necessary to apply the electronically control technology to the diesel engine and it is the direction of the development of the diesel engine in future. As one of the electronically controlled diesel technology, the research of electronic controlled unit (ECU) has made remarkable progress. From only fuel control in early to control every system of the engine at present, the electronically controlled diesel engine has many contents such as malfunction diagnose and real time management. More and more advanced electronically controlled technologies have been adopted widely in the electronically controlled unit.The control methodology on the electronically controlled diesel engine and its development has been analyzed in this paper. The method and the technology of ECU design have been discussed. Combining with the state of our research, the control strategy of the electronically controlled diesel engine and the design method of ECU have been put forward. All of these include determining control function, compartmentalizing the sub-functions, defining key of control links and control scheme have been brought forward. The control logic has been designed to meet the requirements of the control function of fuel injection and gas exchange system. The criterion of speed stable state has been proposed in this paper.All of an isolation circuit, a modulation circuit and a driving circuit have been designed in this paper to fit the controller hardware. Absorbing the advantages of the former driving circuit, the improved circuit has been made great progress on its wide practicability. It can reduce the driving voltage from 110 volts to 36 volts and reduce the number of components in the circuit without reducing the circuit performance.As a widely useful software technology, Real Time Operation System (RTOS) has been used to design the controller software in this paper. The clock ticks, the synchronization of tasks and the task division have been designed to meet the requirement of control logic of the electronically controlled diesel engine. The accuracy of controlled time order has achieved 0.1 milliseconds. The goal ofmodularization design has achieved by means of the RTOS technology. In the process of control software design, a control scheme of common rail pressure has been designed to make the pressure stable and the common rail pressure tested by the electronically control system test bench. The performance of the electronically controlled common rail executor has been gained by experiment.On the basis of the experiment, a dynamic model of 4135 diesel engine has been established. The dynamic characteristics of diesel engine have deeply been analyzed in this paper by the Generalized Frequency Response Function (GFRF) method. The feedback linearization method has been adopted to correct the nonlinear character of the diesel engine and to design the speed controller in order to achieve the stability of the speed control and the dynamic response consistence in the large scope. All these designs have been demonstrated mathematically and also been simulated.