リエントラント型燃焼室の形状が二段噴射ディーゼル機関の性能・排気に及ぼす影響

Abstract

This study aims at finding the favorable combination of combustion-chamber shape and injection parameters when using two-stage injection. The experiments were carried out with various injection conditions, such as spray angle and injection timings and fuel-quantity ratio of two-stage injection, using three types of combustion chamber at low and middle loads. The results show that the strong flow in reentrant-type combustion chamber makes over-lean mixture from first-stage injection at a low load leading to an increase in unburned species emissions, while smoke emission is markedly reduced at a middle load. Increasing first-injection quantity reduces unburned species emissions at a low load but increases NOx emissions. The larger bowl diameter is effective to reduce unburned species emission for later first-stage injection at a low load; however, it causes an increase in smoke emission at a middle load.

二段噴射を用いた無過給単気筒ディーゼル機関において口径やリップ形状の異なるリエントラント型燃焼室を用いて，噴射角度，噴射量配分，噴射時期を変更して実験を行った結果について報告し，NOx，黒煙，未燃物質，燃焼騒音および燃費を同時に抑制する燃焼制御の方針について検討した．