| Diesel engine, due to its higher thermal efficiency, higher torque under low speed, wider range of power, better fuel economy, and other advantages, has been widely employed in various fields. However, under the background of further deterioration in the world’s energy environment situation and the increasingly stringent emission regulations, requirements on diesel engine power and emission performance continues to increase. High-pressure common rail injector response characteristics is a main index to decide diesel engine fuel injection law and combustion exothermic regularity, mainly for injection opening delay and closing delay of the fuel injectors. The response characteristics of the fuel injector directly affects the fuel injection quantity, injection commencement and termination time and flexibility of the control, ultimately affect the engine power and emission performance. In order to further improve the response characteristics of the common rail injector, the argument analyzes the key structure parameters of the injector response characteristics and control valve flow capacity.Firstly, this paper has simplified the injectors, and according to the structure and working principle of the injector, established the corresponding mathematical and physical model. The paper has applied the software AMESim to establish the simulation model of injector working process, and compared the fuel injection quantity and duration results with the same condition test results. It show that the simulation calculation results and the real situation are more consistent, the model can be applied in the simulation study of high-pressure common rail fuel injector response characteristics.Secondly, based on the established numerical bench, it used the injector model system studied injection pressure, control valve drive, control valve spring preload, the maximum lift of control valve, volume of control room,oil inlet pole diameter, oil outlet pole diameter, control plunger diameter, the needle valve spring preload, needle valve sealing diameter, needle seal seat cone angle and other structural parameters effects on the response characteristics of injector, and summarizes the influences of the various parameters to find the selected range of the optimal value.Thirdly, due to one-dimensional simulation considered control room as the concentrative volume, it cannot reflect the structure shape effect on the response characteristics of injector. The paper has applied CFD three dimensional transient flow numerical simulation method, to study the control chamber assembly flow characteristics, analysis the fillet of the oil channel, control valve type, sealing cone angle and the oil outlet pole structure for chamber assembly flow characteristics of control, improve the control of chamber assembly flow capacity of the structural optimization method.Lastly, on the basis of previous work, it has used the orthogonal test method to enhance injector response characteristics as the optimization objective, and matched the key parameters of the effect of fuel injector response characteristics. It drew the optimized design scheme of the injector response characteristics.The specific conclusions are as follows:when the control room inlet\outlet oil pole aperture is0.26mm\0.28mm, control plunger diameter is4.25mm, needle valve spring preload is140n, control valve spring preload is90N, needle valve sealing diameter is2mm, oil outlet polr flow coefficient IS0.95, the injector response characteristics is the best. After optimization of the injector, the open response and close response have been significantly improved, injection of overall response characteristics are improved by13.3%.Injector response characteristics also has certain promotion, in ensure continuous injection in the same period the premise, single injection quantity increased3.87%. It has realized the injector structure parameters optimization for the target of improving the response characteristics. |
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