Engine Autostop Control via Fuel Rail Temperature
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing engine autostop and autostart control systems face issues with high fuel rail pressure during shutdown and restart, leading to degraded fuel injection control accuracy, rough restarts, increased emissions, and potential engine misfires, especially when high pressure direct fuel injection systems are used.
Innovation Solution
The engine control system adjusts engine operation based on fuel rail temperature, automatically stopping or delaying shutdown to manage fuel rail pressure, and adjusts restart conditions to maintain accurate fuel injection by varying engine start speed and torque, ensuring fuel rail pressure is within a safe range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If automatic engine shut-down is enabled during idle stop conditions, then fuel efficiency is improved, but fuel rail pressure may rise to undesirably high levels during shutdown
Solution Approach 1:
The control system performs preliminary action by detecting high fuel rail temperature conditions before initiating engine shutdown and preemptively adjusting fuel injection parameters or shutdown timing to prevent excessive fuel rail pressure buildup during the shutdown period, thereby maintaining both fuel efficiency benefits and pressure control
Solution Approach 2:
The system changes operational parameters by modifying fuel injection quantity, injection timing, or shutdown duration based on real-time fuel rail temperature and pressure conditions, allowing the engine shutdown system to adapt to varying thermal states and prevent harmful pressure levels while maintaining fuel efficiency
2Productivity
If engine shutdown is performed at high fuel rail temperatures, then idle stop operation is maintained, but fuel injection control accuracy degrades upon restart
Solution Approach 1:
The control system implements feedback by continuously monitoring fuel rail temperature and pressure conditions, using this information to determine appropriate shutdown timing and to adjust restart parameters, ensuring that fuel injection control accuracy is restored after shutdown by basing restart decisions on actual measured conditions rather than fixed schedules
Solution Approach 2:
The system applies dynamics by making the shutdown and restart parameters variable rather than fixed, adjusting injection pulse widths, fuel pump operation, and restart timing based on real-time fuel rail conditions, allowing the system to maintain injection control accuracy across varying temperature and pressure states
3Reliability
If high fuel rail pressure occurs during shutdown, then engine idle stop function is compromised, but emissions increase and engine misfire occurs
Solution Approach 1:
The control system acts as an intermediary by introducing intermediate control actions between the shutdown command and the actual engine state, such as controlled fuel pump shutdown timing, staged fuel injection reduction, or intermediate pressure relief measures, to prevent direct transition to harmful high-pressure states that cause emissions and misfire
Data Source
AI summary
Systems and methods are described for controlling engine operation of an engine that may be shut-down during engine idle stop conditions. The engine may include a high pressure direct injection fuel system. In one embodiment, a method stops the engine when a temperature of a fuel rail is below a threshold during a selected engine idle stop condition. On the other hand, when the temperature of the fuel rail is above the threshold, engine operation is maintained during the selected engine idle stop condition.