Suppression of super-knock in TC-GDI engine using two-stage injection in intake stroke (TSII)

Abstract

Turbocharging and direct injection are main technologies used for energy-saving gasoline engines. But the biggest challenge is super-knock, whose mechanism is unclear and has no effective strategy to suppress this super-knock until now. The effects of injection strategies on super-knock were experimentally investigated in a turbocharged GDI engine. It was found that two-stage injections during intake stroke (TSII) can eliminate super-knock. Meanwhile, the fuel consumption, emissions and exhaust temperature can keep optimized level. By sweeping the start of the 1st injection (SOI1), end of the 2nd injection (EOI2) and the split injection ratios (ROI2) using 5000 cycles evaluation test at low-speed high load operating point, the optimized injection strategy for the typical TC-GDI engine is TSII with SOI1 at middle of intake stroke, EOI2 at end of intake stroke, and ROI2 of 0.3.