增压直喷汽油机燃油稀释影响研究

Study on the Fuel Dilution of the TGDI Gasoline Engine

通过一款1.5 L增压直喷汽油机,研究了发动机的设计参数、用户使用场景等对燃油稀释的影响。结果表明:减少喷油器喷嘴数量及缩小喷雾锥角,汽油撞壁量大幅减少,燃油稀释率最大降低了16.7%;随着喷油次数的增加,燃油稀释率逐渐降低,最大降低了61.4%;配缸间隙增加,导致燃油稀释率升高;在机油温度较低的工况下运行时,随着运行次数增加,燃油稀释率逐渐升高,将机油温度提高后继续运行,燃油稀释率逐渐降低,最大降低了44.44%。同时研究了燃油稀释率对机油特性的影响,结果表明:机油的运动黏度随燃油稀释率的升高逐步下降,燃油稀释率越高,运动黏度下降率越大,最高下降率达到77.86%;当燃油稀释率为6.03%时,运动黏度下降率达到19.74%,接近换油指标要求的20%运动黏度下降率;机油的酸值增加量随燃油稀释率的升高呈不规则变化,而“碱值-酸值”指标随燃油稀释率的升高变化不大,满足换油指标的要求。

The influence of engine design parameters and usage scenario etc on the fuel dilution was studied based on a 1.5L TGDI gasoline engine.The research results show:Reducing the number of injector nozzles and spray angle can reduce the amount of gasoline hitting the wall significantly,and fuel dilution was 16.7 percent reduced maximum.As the number of oil injection increases,the fuel dilution rate decreases gradually,with a maximum decrease of 61.4%.The increase of cylinder clearance will lead to the increase of fuel dilution rate.When running at low oil temperature,with the increase of running times,the fuel dilution rate of gasoline engine increases gradually;when engine continues running after the oil temperature is raised,the fuel dilution rate decreases gradually,with a maximum decrease of 44.44%.The effect of fuel dilution rate on engine oil characteristics is studied.The research results show:When the fuel dilution increases,the kinematic viscosity decreases,the higher the fuel dilution rate,the greater the decrease rate the kinematic viscosity,with a maximum decrease rate of 77.86%;When the fuel dilution rate reaches 6.03%,the kinematic viscosity decreases by 19.74%,close to 20%motion viscosity decrease rate required by the oil change index,;The acid value of oil increases irregularly with the increase of fuel dilution rate,but the alkali-acid value changes little,which meets the requirement of oil change index.