To get high thermal efficiency, the engine should be operated according as constant-pressure heating cycle. Consequently, the combustion mode should be followed premixed approximate isostatic combustion theory. 理论研究发现:受机件强度的限制,压燃式内燃机必须限制其循环最高压力,为得到较高的热效率,需按定压加热循环工作,因此柴油机燃烧模式需遵循预混合近似等压燃烧理论。