利用双拖动示功图标定上止点

A Method for Determinating TDC of I. C. Engines by Using Two Motoring Indicator Diagrams

本文从拖动过程能量守恒方程出发,推导了热力损失角的近似表达式,证明拖动过程热力损失角主要决定于散热损失率与漏气热损失率之和的大小。计算机模拟的结果与近似表达式表示的规律一致;并发现,当总散热率在宽广的范围内变化时,高低两转速下的拖动示功图热力损失角的差值与其中一转速下的热力损失角之间存在线性关系,由此提出了利用双拖动示功图标定上止点的方法.

An approximate expression for Aφ_l,the heat loss angle of TDC of IC engines, is deduced from the equation of conservation of energy in motoring process of engines. It shows that △φi increases proportionally with the increasing of heat loss due to heat transfer and gas leakage. A computer code is also made to study the influential factors of △φi. The simulating results are consistent in tendency with that given by the approximate expression and it is observed that the difference of value of the heat loss angles of TDC under two different engine speeds has a linear relationship with one of these two heat loss angles of TDC. Finally, a method for determinating TDC of engines is proposed.