Influence of methanol fuel on lubrication and exhaust smoke on a small two-stroke spark ignition engine

对一台小型二冲程火花点火发动机燃用甲醇和汽油时的燃烧室沉积、排烟和气缸摩擦学进行了研究。甲醇显示出作为内燃机替代燃料的前景。最近，它也被认为是一种很好的燃料电池候选燃料。小型二冲程循环发动机活塞顶面上形成的电荷耦合器件比四冲程发动机多得多，这是因为前者具有燃料和润滑油在气缸内一起供应的独特机制。众所周知，火花点火发动机中的电荷耦合器件存在辛烷值要求提高、废气中NOx排放以及发动机气缸和活塞的摩擦学条件发生变化等各种问题。针对以汽油和甲醇为燃料的二冲程发动机，研究了润滑油在气缸内的温度、压力、气体流动条件和滞留时间对电荷耦合效应的影响，以及电荷耦合效应的形成规律与活塞冠面温度分布的关系。通过使用具有已知熔点的易熔塞来估计活塞冠上的温度分布。我们还对发动机的润滑和排烟进行了试验。

We made a study on the combustion chamber deposit (CCD) formation, exhaust smoke and cylinder tribology in a small two-stroke spark ignition engine using methanol and/or gasoline as fuel. The methanol shows a promise as an alternative fuel for internal combustion engines. Recently, it is also considered to be a good candidate as a fuel of fuel cells. The CCD formed on the piston crown surface in a small two-stroke cycle engine is much more than that in a four-stroke one, because the former has such a unique mechanism that fuel and lubricant oil are supplied together in the cylinder. It has been known that the CCD in a spark ignition engine makes such various problems as an increase in the octane-number requirement and a NOx emission in the exhaust gas and a change in tribological conditions of engine cylinders and pistons. Generation of the CCD is influenced by the temperature, pressure, gas flow conditions or retention period of the lubrication oil in the cylinder.We studied mechanisms for deposit generation and relations between CCD formation patterns and the temperature profiles on the piston crown surface for the two-stroke engine using gasoline and methanol as a fuel. The temperature profiles on the piston crown were estimated by using fusible plugs that had the known melting points. We also made experiments about the lubrication and exhaust smoke of an engine.