Hybrid Engine Start Prediction for Driveline Torque Response
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Solution Overview
Problem
Hybrid vehicle engines face challenges in providing desirable torque response during transmission upshifts, leading to reduced driveline torque and decreased fuel efficiency, as existing methods fail to predict and meet torque demands accurately after gear changes.
Innovation Solution
A method is developed to predict desired torque after a transmission upshift and start the engine if the predicted torque exceeds a threshold, ensuring engine torque is available to the driveline, thereby maintaining driveline torque and improving fuel efficiency by allowing the engine to be stopped during idle conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is stopped to conserve fuel during idle conditions, then fuel economy is improved, but driveline torque response deteriorates during transmission upshifts
Solution Approach 1:
The system performs preliminary action by predicting the desired torque after a transmission upshift before the upshift occurs. Based on this prediction, the engine is started in advance if the predicted torque exceeds a threshold, ensuring that the engine is ready to provide torque immediately when needed, thus preventing driveline torque reductions during the upshift
2Force
If the engine is started based on increasing torque demand, then driveline torque is maintained, but fuel economy deteriorates due to unnecessary engine operation
Solution Approach 1:
Instead of reacting to increasing torque demand, the system performs preliminary action by predicting the future torque demand after the transmission upshift. This allows the engine to be started only when truly necessary (when predicted torque exceeds threshold), avoiding unnecessary engine operations and improving fuel economy while still maintaining driveline torque when needed
3Loss of energy
If the engine is stopped during idle conditions, then fuel consumption is reduced, but the possibility of noticeable driveline torque reductions during gear shifting increases
Solution Approach 1:
The system performs preliminary action by predicting the desired torque after the transmission upshift before the upshift occurs. If the predicted torque exceeds a threshold, the engine is started in advance, ensuring that the engine is ready to provide torque immediately when needed. This prevents noticeable driveline torque reductions during the upshift while still allowing the engine to be stopped during idle conditions when torque is not needed
Solution Approach 2:
The system uses feedback by continuously monitoring transmission shift events and comparing the predicted torque demand with the threshold. This feedback mechanism allows the control system to make informed decisions about engine starting, balancing fuel consumption and driveline torque stability by starting the engine only when the predicted torque demand justifies it
Data Source
AI summary
Systems and methods for improving operation of a hybrid vehicle are presented. In one example, torque demand of a driveline after a shift is forecast to determine if it is desirable to start the engine early so that engine torque is available after the shift. The approach may improve vehicle torque response.