In-Cylinder Injection Fuel Pressure Control for Engine Stop Leakage

The patent implements dynamic adjustment of the target fuel pressure reduction rate based on the detected actual fuel pressure. When the difference between actual and target pressure exceeds a predetermined threshold, the reduction rate is automatically lowered to prevent undershoot. This dynamic control ensures fuel pressure is reduced smoothly without causing combustion deterioration, while still achieving the goal of reducing fuel leakage after engine stop.

The patent employs feedback control by continuously detecting actual fuel pressure and comparing it with the target fuel pressure. The detected pressure difference is fed back to adjust the target fuel pressure reduction rate in real-time. This feedback mechanism prevents the actual pressure from falling below the target pressure, thereby avoiding combustion deterioration while effectively reducing fuel leakage.

The patent implements preliminary action by detecting engine stop conditions in advance and proactively reducing the target fuel pressure before the engine actually stops. This early intervention allows the fuel pressure to be gradually reduced during the period when the engine is still running but about to stop, thereby preventing excessive fuel leakage after stoppage while maintaining injection performance during the transition period.

The system dynamically adjusts the target fuel pressure based on engine operating conditions and stop detection. When engine stop is detected, the target pressure is gradually reduced at a controlled rate rather than maintaining high pressure until stop. This dynamic adjustment ensures optimal balance between injection performance during the transition and leakage prevention after stop.