增压直喷汽油机机械损失及分解摩擦试验研究

Experimental study on mechanical loss and friction decomposition of a turbocharged direct injection gasoline engine

基于AVL试验台架,对一款先进车用增压直喷汽油机分别开展整机摩擦试验和分解摩擦试验,研究全转速范围内整机机械损失和各子系统机械损失的变化规律。研究结果表明:节气门开启与否对整机机械损失压力影响较大;在中低转速区域,节气门开启后发动机机械损失压力明显下降;但在高转速区域,发动机机械损失压力上升;在节气门开启时,增压器才对发动机倒拖功率有影响;随着转速增加,附件损失和曲轴损失所占百分比变化很小,气门机构损失所占百分比逐渐减小,而活塞连杆损失百分比逐渐增加;在低转速时,发动机机械损失主要为气门机构损失,1 000 r/min时达到52.3%;在高转速时,除附件损失外,其余3种损失大体相当。以上规律为提高增压直喷汽油机的机械效率提供依据。

The engine motored test and friction decomposition test were conducted on an advanced turbocharged direct injection gasoline engine based on AVL test bench,and then the engine friction losses and various subsystem friction losses were obtained in the whole speed range.The results show that the state of throttle has an obvious effect on the engine mechanical loss.At the low and middle speed,when the throttle is opened,the engine mechanical loss decreases obviously;but at the high speed,the engine mechanical loss rises.Only when the throttle is opened,the turbocharger will have effect on the engine motored power.With the increase of engine speed,the percentages of attachment loss and crankshaft friction loss only change a little.The percentage of valve train loss decreases gradually,while the percentage of piston and connecting rod friction loss increases gradually.At the low speed,the engine mechanical loss is mainly in form of valve train loss,and its percentage goes up to52.3%at1000r/min.At the high speed,the remaining three losses are close to each other except the attachment loss.The above rules have provided basic data for improving the mechanical efficiency of turbocharged direct injection gasoline engine.