【摘要】 在进行发动机燃烧分析时,正确确定发动机动态上止点相位非常重要。对直喷式柴油机热力损失角进行了模拟分析,分析结果表明：直喷式柴油机的热力损失角（?）_m可近似分成由于散热引起的热力损失角（?）_q和因为漏气所引起的热力损失角（?）_h两部分。将（?）_m及（?）_q、（?）_h与相应转速相乘,得到的乘积（?）_mn与（?）_qn变化规律近似一致,（?）_hn近似为常量。利用这一规律可以将（?）_q从（?）_m中分离出来。就此,提出了修正后的利用双拖示功图确定上止点的方法。更多还原

【Abstract】 It is very important to identify the engine dynamic top dead center phase in the combusting analysis of IC engine.Numerical simulation analysis of a DI diesel engine’s thermodynamic loss angle under motoring conditions were presented.Special attention was given to the thermodynamic loss angle （TLA）（?）_m·Analyzing results indicate that （?）_m consist of （?）_q and （?）_h which are caused by heat transfer and gas leakage. Multiply （?）m,（?）_q and （?）_h by engine rotating speed,the products （?）_mn and （?）_qn are parallel lines,and （?）_hn is close to constant.It is shown that the change rule in （?）_mn with speed is almost accordant with the change of （?）_qn,so that （?）_q could be extracted form （?）_m.Considering these relationships,an amendment was made for the method of determining TDC of DI engine using two motoring indicator diagrams.更多还原