Air-assisted Electronic Control Fuel Injection System Design And Research On Spray Characteristics

Piston engine is widely used as a power unit in small aviation equipment,especially unmanned aerial vehicles.Aviation heavy oil(referring to light diesel or aviation kerosene)is mainly used as fuel for small aviation piston engines.Compared with gasoline,it has higher flash point,lower volatility,lower cost and better safety.However,aviation heavy oil is difficult to atomize.The current mainstream solution is to use an air-assisted fuel injection system.Compressed air is introduced in the airassisted fuel injection system to premix it with fuel and then sprays the fuel-air mixture.The aerodynamic force is used to promote fuel breakup and achieve a good atomization effect with a lower injection pressure.The system can improve engine power performance and emission performance.At present,foreign countries have a mature industrial system in this field.The domestic start is relatively late,and technology products and research experience are relatively scarce.Therefore,the design and research of this system is very important.Based on the principle of air-assisted injection,this paper designed an air-assisted electronic control fuel injection system,equipped with an electronic control module,and studied the spray characteristics of the system.First,an overall design plan was proposed according to the function of the air-assisted electronic control fuel injection system and experiment requirements,and each functional module was divided.The spray process and mechanism were analyzed,and the parameters of the spray characteristics were introduced.The relevant algorithm theory of computer vision was adopted,and the spray image processing software was developed using C++ for experiment data processing.Subsequently,the design and development of the control module was carried out.The MCU MC9S12XEP100 MAL and other chips were selected to design the hardware circuit,draw the PCB,and weld the circuit board.C and C#were used to develop the lower computer software and the upper computer software.They were made to communicate with each other,and cooperate with the hardware resource,for controlling the injector and adjusting the parameters.Finally,experiments were carried out on this system to study the influence of different parameters on the characteristics of diesel air-assisted spray.The research results show that increasing the fuel injection pressure will increase the spray penetration and spray angle.When the fuel temperature changes in a lower range,the spray penetration and spray angle do not change significantly.While the fuel temperature rises to a certain level,the spray penetration decreases and the spray angle increases.Increasing the fuel injection pulse width or reducing the jet pulse width can increase the spray angle,but it has no effect on the spray penetration.The fuel-air interval has basically no effect on spray penetration and spray angle.