Engine Restart Control via Transmission Engagement and Torque Adjustment
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Solution Overview
Problem
Existing engine restart methods in stop/start systems often result in delayed clutch engagement due to mismatched engine and transmission speeds, leading to increased clutch degradation and vehicle surge during restart.
Innovation Solution
A method for controlling an engine coupled to a transmission, where the transmission is engaged to assist in spinning up the engine from rest, and engine controls such as throttle position, spark advance, and fuel timing are adjusted to facilitate a smooth restart, reducing clutch slippage and torque disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the clutch is engaged before the engine speed is close to the transmission speed, then the engine restart is faster, but clutch degradation increases
Solution Approach 1:
The system performs preliminary actions by adjusting engine controls (throttle position, spark advance, cam angle, fuel timing) before clutch engagement to pre-synchronize engine speed with transmission speed, thereby preparing the system to avoid excessive clutch slippage while maintaining fast restart
Solution Approach 2:
The control system continuously monitors engine speed and transmission speed, using this feedback to dynamically adjust engine controls and determine the optimal moment for clutch engagement, ensuring engine speed is sufficiently close to transmission speed before engagement occurs
2Reliability
If the clutch is engaged after bringing engine speed close to transmission speed, then clutch degradation is reduced, but clutch engagement is delayed
Solution Approach 1:
Engine controls are adjusted in advance during the restart process to proactively manage speed synchronization, allowing the system to achieve speed matching more quickly and reduce the overall time penalty of waiting for engagement
Solution Approach 2:
The system dynamically adjusts multiple engine parameters (throttle position, spark advance, cam angle, fuel timing) in real-time during the restart process, allowing flexible optimization of the speed synchronization rate to balance restart speed with clutch protection
3Device complexity
If engine controls are not adjusted during restart, then the control system is simpler, but vehicle surge and clutch slippage increase
Solution Approach 1:
The existing engine control system, already capable of managing normal engine operation, is extended to also manage the restart process by adjusting the same control parameters (throttle, spark, cam angle, fuel timing) used during normal operation, thereby handling restart without adding dedicated complex hardware
Data Source
AI summary
Various systems and methods are described for controlling an engine in a vehicle, the engine being coupled to a transmission. One example method comprises, under selected braking conditions, shutting-off the engine and spinning-down the engine to rest while the vehicle is traveling, and in response to a foot-off-brake event, restarting the engine by at least partially engaging the transmission and adjusting engine torque control actuators.