No abstract

In order to understand better the process of hydrocarbon formation and the effect of the top-land crevice and the oil layer of the cylinder liner on unburned hydrocarbons during cold start and idling periods, the temperature of the piston top-land and liner was measured. Based on the measured results, the amount of unburned hydrocarbons from the crevice and liner has been predicted. It was found that the temperature of the piston top-land and cylinder liner took about 150-200 s to reach its equilibrium state as the engine started up. The concentration of hydrocarbons from the top-land crevice and from the oil layer will be reduced to 40 and 75 per cent of its initial value respectively. It is considered that a reduction in piston thermal capacity can reduce the total unburned hydrocarbons during this transient period owing to quick minimization of the top-land crevice volume and rapid increase in mixture temperature in the crevice region.

No abstract

It is very important to know the temperature history in a spark-ignition engine when the phenomenon of knocking is being studied. However, measurement of the gas temperature is not easy and some work has been done using laser diagnostics etc. In this study, the temperature history until the time of occurrence of knocking in a spark-ignition engine was measured by a form of laser interferometry designed especially for use in the combustion chamber. Not only the change in temperature but also the absolute value of the temperature could be determined with this interferometer, by utilizing the change of the gas density on the reference side. This is a non-intrusive measurement and high resolution is expected. The temperature resolution is about 5 K near the occurrence of knocking.

No abstract