Combustion Improvement of an HSDI Diesel Engine with Increasing Injection-pressure and Injection Rate Shaping

Abstract

Effects of high-injection-pressure up to 240MPa and injection-rate-shaping on rating power and its revolution, and on exhaust emissions from an HSDI diesel were investigated using single-cylinder research engine. Fuel-air equivalent ratio (φ) limited by exhaust smoke number is strongly associated with velocity ratio of fuel-spray to squish air motion. It is confirmed high injection pressure of 240MPa realizes equivalence ratio of φ0.78 at 5000rpm. Effect of initial injection-rate-suppression on exhaust emission decreases as charging efficiency is increased. High injection pressure over 200MPa is also effective on reduction of NOx and Smoke with combination of high-boost pressure and high EGR-ratio.