Hybrid Engine Start Control for Creep Mode Clutch Pressure
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Solution Overview
Problem
Hybrid vehicles face challenges in achieving consistent engine starts when stationary or in creep mode, leading to potential driveline torque disturbances and reduced vehicle responsiveness.
Innovation Solution
A method involving a controller that schedules the internal combustion engine to start by closing a driveline disconnect clutch, while increasing line pressure to a threshold before engaging the clutch, and switching to a flywheel starter if the driver demand pedal is applied, to ensure consistent and responsive engine starting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the driveline disconnect clutch is closed immediately to start the engine, then vehicle responsiveness is improved, but engine starting consistency deteriorates due to insufficient line pressure
Solution Approach 1:
The system performs preliminary action by increasing line pressure before closing the driveline disconnect clutch to start the engine. The controller monitors line pressure and only closes the clutch when pressure reaches a threshold level, ensuring consistent clutch engagement and reliable engine starting while maintaining vehicle responsiveness.
2Reliability
If the driveline disconnect clutch is delayed until line pressure reaches threshold, then engine starting consistency is improved, but vehicle responsiveness deteriorates
Solution Approach 1:
The system applies dynamics by making the clutch closing timing adaptive rather than fixed. The controller dynamically adjusts the clutch closing decision based on real-time line pressure conditions and driver demand pedal input. When line pressure is sufficient, the clutch closes promptly for responsiveness; when pressure is low, the system waits or switches to flywheel starter to ensure reliable engine starting.
Solution Approach 2:
The system changes the operational parameters of the engine starting process based on line pressure conditions. Instead of using a fixed timing for clutch closing, the controller adjusts the timing parameter dynamically - closing the clutch immediately when line pressure is high, delaying closure when pressure is building, or switching to an alternative starting method when pressure remains insufficient, thereby resolving the contradiction between responsiveness and reliability.
3Loss of time
If the driveline disconnect clutch is closed during creep mode with low line pressure, then quick engine start is achieved, but driveline torque disturbances occur
Solution Approach 1:
The system uses feedback by continuously monitoring line pressure and using this information to control the clutch closing decision. The controller receives feedback on the actual line pressure condition and adjusts the clutch closing timing accordingly. This feedback mechanism prevents clutch closing during creep mode when line pressure is insufficient, thereby avoiding driveline torque disturbances while still achieving quick engine starts when conditions are favorable.
4Adaptability or versatility
If both engine starting devices are used under all conditions, then starting flexibility is improved, but system complexity increases
Solution Approach 1:
The system applies local quality by assigning different starting devices to different operating conditions rather than using a single uniform approach. The driveline disconnect clutch is used when line pressure conditions are favorable (providing responsiveness), while the flywheel starter is used when line pressure is insufficient (ensuring reliability). This conditional assignment optimizes the use of each starting device for its最适合的 operating scenario without requiring overly complex control logic.
Data Source
AI summary
Systems and methods for selecting which of a plurality of engine starting devices starts an internal combustion engine of a hybrid vehicle are presented. In one example, engine starting devices may be selected and operated while a vehicle is operating in a creep mode. The system and method may place a driveline disconnect clutch in a wait state or engage a flywheel starter to improve engine starting.