Made in China New Diesel Fuel Injector 0 445 110 218 0445110218 for Diesel Engine

The effect of different injection pressures on the combustion process

Through the engine bench experiment, different injection pressure levels were set to observe the effect on the combustion process. The experimental results show that with the increase of injection pressure, the combustion start point is slightly advanced and the combustion duration is shortened. At higher injection pressures, fuel atomization is more adequate, combustion is closer to the ideal isovolumetric combustion process, and the indicated thermal efficiency of the engine is increased. For example, when the injection pressure is increased from 1200 bar to 1800 bar, the indicated thermal efficiency increases by about 5%, and at the same time the NOx emission increases, but the increase in NOx emission can be reduced to a certain extent through reasonable combustion optimization measures.

Influence of injection timing on engine performance and emissions

Experiments were conducted to change the injection timing, and it was found that when the injection advance angle was too large, the engine worked roughly, the in-cylinder pressure increased too quickly, and the NOx emission increased sharply; whereas too late injection would lead to incomplete combustion, increased fuel consumption, and increased HC and CO emissions. Under medium load conditions, finding an optimal injection timing can make the engine's power, economy and emission performance reach a better balance. For example, for a medium-speed diesel engine, when the injection advance angle is in the range of 8° - 10°CA BTDC (before top stop), the effective power of the engine is higher, the fuel consumption rate is lower, and the NOx, HC and CO emissions meet the relevant regulatory requirements.

Influence of carbon deposits in injector holes on atomization quality

Long-term use of the injector orifices are prone to carbon deposits, and by comparing the atomization characteristics of clean injectors and carbon injectors, it is found that carbon deposits in the orifices lead to a reduction in the orifices' flow cross-sectional area, an uneven injection rate, and poor atomization quality. Poor atomization of diesel fuel in the combustion process will form larger particles of carbon soot, increasing PM emissions, but also affects the combustion efficiency, so that the engine power down, fuel consumption increases.

Diesel fuel injector performance optimization strategy
(i) Optimization of injector structure parameters
Optimization of injector parameters: According to the specific working conditions and performance requirements of the engine, precisely design the number of injector holes, diameter, taper and length and other parameters. For high speed and high load engines, the number of orifices can be increased and the diameter of the orifices can be reduced to improve the atomization quality; for low load conditions, the orifice parameters can be adjusted appropriately in order to take into account the fuel economy and emission performance. Through the combination of CFD (Computational Fluid Dynamics) simulation and experimental methods, the best combination of orifice parameters is determined to optimize the spray pattern, penetration distance and droplet size distribution of diesel fuel.
Needle valve lift optimization: Reasonable design of the lift curve of the needle valve can not only ensure that there is enough cross-sectional area of fuel flow in the injection process to achieve rapid injection, but also can quickly cut off the fuel supply when the needle valve is closed to prevent dripping phenomenon. Adopting the variable needle valve lift technology, the needle valve lift is adjusted in real time according to the engine conditions, and a smaller needle valve lift is used under small load conditions to reduce the fuel injection volume while improving the atomization quality; the needle valve lift is increased under large load conditions to meet the engine's demand for fuel volume, thus improving the adaptability and overall performance of the injector.

(ii) Improvement of injector driving circuit
Optimize the design of the injector driving circuit to improve the response speed and driving ability of the solenoid coil. Adopting high voltage and high current driving pulse can make the solenoid coil produce enough electromagnetic force quickly, shorten the response time of needle valve opening and closing, and improve the accuracy and repeatability of fuel injection. At the same time, the protection function of the drive circuit is increased to prevent the electromagnetic coil from being damaged due to over-voltage, over-current, etc., so as to improve the reliability and service life of the injector. For example, the adoption of intelligent drive chip can automatically adjust the parameters of the drive pulse according to the running state of the engine to realize the precise control of the injector.

(iii) Adopting new materials to improve injector performance
Injector materials: use high temperature, wear-resistant, corrosion-resistant new alloy materials to manufacture injector nozzles, such as silicon carbide (SiC)-based composite materials. This material has excellent high-temperature mechanical properties and chemical stability, can withstand higher injection pressure and temperature, reduce the nozzle wear and carbon phenomenon, long-term maintain good atomization performance, thereby improving the reliability and durability of the injector, reduce engine maintenance costs.
Sealing materials: high-performance sealing materials, such as fluorine rubber (FKM) or perfluoroether rubber (FFKM), are used to ensure good sealing performance of the injector under high-pressure and high-temperature environments, prevent fuel leakage, and improve the efficiency and safety of the fuel injection system.