Engine Start Torque Synchronization via Transmission Clutch Control
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Solution Overview
Problem
Vehicle engines that automatically start and stop experience torque management issues, leading to inconsistent wheel torque response and driver perception of engine restarting, particularly due to transmission clutch states during engine restart.
Innovation Solution
Adjusting the transmission tie-up force in response to the timing of the first combustion event of a cylinder during engine start to synchronize torque transfer and improve starting consistency and driver demand response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If transmission clutches are kept in open state during engine starting, then wheel torque response delay is reduced, but torque transfer timing becomes inconsistent
Solution Approach 1:
The transmission clutch is actuated in advance based on predicted engine starting conditions (crankshaft position, combustion timing) before actual torque transfer begins. This preliminary engagement ensures the clutch is ready to transfer torque immediately when the engine starts, eliminating response delay while maintaining consistent timing through predictive control.
Solution Approach 2:
The system uses feedback from engine position sensors, crankshaft position sensors, and combustion event detection to dynamically adjust clutch actuation timing. This closed-loop control ensures the clutch engages at the optimal moment for each starting event, maintaining both fast response and consistent timing across multiple starts.
2Reliability
If transmission tie-up force is increased during engine stop, then torque management is improved, but driver-perceived wheel torque response deteriorates
Solution Approach 1:
The transmission tie-up force is dynamically adjusted based on real-time engine conditions during starting. The clutch actuation force and timing are modified according to detected combustion events and crankshaft position, allowing the system to optimize both torque management and response speed for each specific starting scenario rather than using fixed tie-up forces.
3Device complexity
If engine starting timing is used for torque transfer, then torque management is simplified, but starting consistency deteriorates due to variable timing
Solution Approach 1:
The system incorporates feedback from combustion event detection and crankshaft position sensing to dynamically adjust clutch actuation timing. This ensures torque transfer is synchronized with the actual first combustion event of each cylinder, maintaining consistent starting performance while preserving the simplicity of using engine timing as the control basis.
Data Source
AI summary
A method for improving starting of an engine that may be repeatedly stopped and started is presented. In one embodiment, the method adjusts a transmission actuator in response to engine combustion during an engine start. The method may improve vehicle launch for stop/start vehicles.