Study on an opposed-injection stratified-charge combustion system

The direct-injection stratified-charge engine is expected to be an alternative to the conventional spark-ignition engines for its high thermal efficiency and low CO and NO_x emission levels. Its actual utilization, however, is prevented by high unburned hydrocarbon emission levels especially during light-load operations. In order to conquer this problem, an opposed-injection stratified-charge system was examined using a pancake-type constant volume bomb, where fuel was injected nearly towards the center of the bomb by a pair of fuel injectors attached oppositely to the circumferential wall of the bomb. Unburned hydrocarbons were reduced compared with the basic radial fuel injection stratified-charge system with a single injector. It was considered that the interactions of the two fuel jets promoted the local fuel-air mixing and increased the flame propagation velocity leaving less over-lean mixture.