新型增压式高压共轨系统的供油效率和能量利用率的研究

Research on Delivery Efficiency and Energy Availability of New Boost High Pressure Common-Rail System

针对新型增压式高压共轨喷射系统,利用Flowmaster软件建立了系统的仿真模型,分析了轨压、控制室进出油量孔直径、增压室容积大小等因素对系统供油效率和能量利用率的影响。仿真结果表明:轨压提高,供油效率明显提高,但是能量利用率明显下降,二者有折中的关系;进回油量孔直径减小,由于回油量减小,供油效率和能量利用率均有一定程度的提高,进油量孔直径变化带来的影响比回油量孔直径变化带来的影响更为明显;此外,由于燃油的压缩性,增压室容积增大会使增压活塞复位过程中的回油增多,且轨压越低,这种影响越明显,回油量越多,从而对供油效率和能量利用率带来不利的影响,因此应尽可能地减小增压室容积。

The simulation model of a new boost high pressure common-rail system was established with software Flowmaster and factors affecting system delivery efficiency and energy efficiency, including rail pressure, diameters of control chamber inlet and outlet holes, pressured chamber volume, etc. were studied. Results show that when rail pressure increases, delivery efficiency rises obviously, but energy efficiency declines largely,there is a trade-off relationship between them. The fuel return decreases as the diameters of inlet and outlet holes reduce,it leads to improvement of both delivery efficiency and energy efficiency to a certain degree. The inlet hole diameter influence on delivery efficiency and energy efficiency is more obviously than the outlet hole diameter. And the pressured chamber volume enlargement will increase the fuel return because of fuel compressibility, the lower the rail pressure, the greater the effect. The fuel return increase will bring about negative effect to delivery and energy efficiencies, so the pressured chamber volume should be reduced.