二系統の燃料噴射システムを備えたディーゼル機関の性能と排気

Abstract

To examine the feasibility of performance improvement by highly flexible fuel injection, a series of experiments were performed using a single-cylinder diesel engine with a dual injector system which includes two sets of common-rail injection systems. This system enables variable injection rate for each injection pulse and a wide-range dwell between injection pulses, i.e. even negative injection dwell can be performed. Experiments with multi-stage injection were conducted with various injection pressures, injection timings, and injection quantities. The results show that switching injector for pilot and main injections reduces smoke emission, and a higher pilot injection pressure increases CO emission without a reduction of smoke emission, while a higher main injection pressure reduces smoke emission with no increase in CO emission. Split-main injection with zero injection dwell increases thermal efficiency under high injection pressure condition. However, negative injection dwell markedly increases smoke emission owing to the spray-to-spray interaction.

噴射率および噴射パターンの設定自由度を高めることによる性能向上の可能性を探るため，単気筒試験機関に独立した二つのコモンレール燃料噴射システムを搭載して実験を行った．その結果に基づいて，多段噴射の各段の噴射圧力・時期，噴射量配分と熱発生率，性能・排気特性との関係について考察した．