早期燃料噴射による希薄予混合ディーゼル燃焼の排出物特性

概要

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There is a gradient of fuel concentration in the spray of conventional direct-injection diesel engines. Therefore, a region of stoichiometric mixture ratio exists in the injected spray and a high concentration of NO_χ is produced. In this study, fuel injection timing was widely advanced to promote the mixing of fuel and air. Using this injection method, the engine could be driven with premixed lean diesel combustion (PREDIC), and NO_χ emissions were greatly reduced. To avoid the fuel spray contacting the cylinder liner, the fuel was injected by two side injectors simultaneously. The two sprays from the side injectors collided with each other and remained in the center region of the cylinder. Thus mixing of fuel and air was promoted by a long ignition delay period. In the case of conventional injection methods, NO_χ could not be reduced to under 400ppm (λ=2.7). In contrast, in the case of PREDIC, NO_χ emissions were reduced to as low as 20ppm (λ=2.7).
一般社団法人日本機械学会の論文
1996-07-25