Study On Pilot Injection For Medium Pressure Common Rail Electronically Controlled Fuel Injection System

The electronically controlled diesel engine is one of important research subjects on engines. The application of electronically controlled technology to diesel engines provides flexibility and effectiveness in reduction of emission, noises and improvement of engine performances, saving energy, etc.In order to improve the all-round performance of diesel engine, a research on the integration of electronically controlled fuel injection and inhale-exhaust system of diesel engine is done by our research group. By analyzing and comparing several kinds of advanced electronically controlled fuel injection systems at home and abroad, a new method is introduced in this paper, which carried out pilot injection in medium pressure and common rail electronically controlled fuel injection system of diesel engine.Based on the former electronically controlled pump of our group, a new type pump has been designed and manufactured, which can implement pilot injection. The plunger, plunger sleeve and spring, as the key parts of the electronic pump, have been designed especially. And the problems in design are discussed in detail.A new high speed and great flow solenoid valve, one of the key parts of electronically controlled fuel injection, is assembled, adjusted, which makes it in good condition, and prepares for injection test in this thesis.The performance of the electronic pump designed firstly, is test on bench in various conditions. The result indicates that the method is effective on the control of initial injection rate. Some different size plungers and plunger sleeves have been designed for the second time. From the test result, some conclusions have been summarized, which is used to optimize the pilot injection for matching the diesel engine.Launching on the whole electronically controlled fuel system, by changing the type of the injector, the area of the nozzle, the ratio of the intensifier's area and the flow of the solenoid valve, some conclusions about enhancing the pressure of the injection are summarized and some other methods are put forward to optimize the whole fuel system, as well.In the end, some conclusions about the electronic controlled fuel system aresummarized, and some ideas about how to optimize the system are involved, too.