Research On Injector For Diesel Engines On Piezoelectric Ceramic

Common-rail system is the development trend of the diesel fuel injection system. In order to meet increasingly requirement of stringent emissions, precise control for diesel injector is being more widely used in common-rail system. Compared with the electromagnetic injector, piezoelectric ceramic injector has a lot of inherent advantages, and is the ideal drive for injector in common-rail system. So in this paper research for piezoelectric ceramic injector is very significant.In this paper piezoelectric ceramic sample is tested by homemade tool of testing micro-displacement. Base on lots of experimental data finding out relationship of the displacement and the voltage, and changes in the temperature influencing on the displacement. By analyzing the test data the writer finds advantage and disadvantage of piezoelectric ceramic as injector drive. In subsequent chapters, designing driving circuit and selecting control algorithm is basing on these testing data.By reading lots of documents on diesel fuel injection system simulating work environment of diesel injector and designing the driving circuit. At first designing a stable 24V DC power supply as replacement of the car battery, this power supply is use for driving piezoelectric ceramic; and then using PWM signal for driving piezoelectric ceramic reference on the method of driving electromagnetic injector, by this method effectively reducing the power consumption and improving response of piezoelectric ceramic; At last, selecting the type of VMOS amplifier as driving circuit of piezoelectric ceramic injector. This circuit can reach the function of following signal, and then make the voltage signal amplified undistorted, these meet requirement of piezoelectric ceramic drive.At last, in this paper researching on control algorithm of piezoelectric ceramic drive. Starting to study traditional PID controller, and finding that this controller don't fit diesel fuel injection system by testing, so it need to be improved, and a single neuron adaptive PID controller replace it. By testing it this kind of controller makes response, controlling precision and adaptation improved greatly.