Hybrid Vehicle Torque Estimation Error Learning
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Solution Overview
Problem
Hybrid vehicles face issues with engine starting and disconnect clutch operation, leading to vibrations, noise, and driveline disturbances due to abrupt torque changes, which affect drivability and fuel efficiency.
Innovation Solution
A method is developed to learn torque estimation errors by analyzing deviations in engine torque, speed, and deceleration during engine shut-down, and using this data to update a torque estimation model for improved torque control during subsequent engine restarts, ensuring smooth transitions between engine-on and engine-off modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the disconnect clutch is applied or released abruptly, then the engine can be quickly connected or disconnected from the driveline, but noise and vibration are introduced to the vehicle driveline disturbing the driver
Solution Approach 1:
The system performs preliminary actions by commanding engine torque adjustments before the disconnect clutch is applied or released. The controller determines a desired engine acceleration profile and commands engine torque to follow this profile, ensuring the engine is ready for smooth clutch transition before the actual clutch engagement or disengagement occurs.
Solution Approach 2:
The system makes the engine torque dynamic and adjustable during the clutch transition process. Rather than maintaining fixed torque, the controller continuously adjusts the commanded engine torque to follow a desired acceleration profile, allowing the engine torque to adapt in real-time to the changing clutch state and minimize driveline disturbances.
2Loss of time
If the disconnect clutch is released too abruptly, then engine shutdown can be achieved quickly, but the driver is disturbed by noise and vibration
Solution Approach 1:
Before the disconnect clutch is released during engine shutdown, the controller determines a desired engine acceleration profile that accounts for the upcoming clutch disengagement. This preliminary torque command ensures the engine is properly conditioned to handle the clutch release smoothly, reducing noise and vibration while achieving quick shutdown.
Solution Approach 2:
The system uses feedback by continuously monitoring actual engine acceleration and comparing it to the desired acceleration profile. The controller adjusts the commanded engine torque based on the difference between actual and desired acceleration, ensuring the engine follows the optimal trajectory for smooth clutch release and minimizing driveline disturbances.
3Ease of operation
If engine torque is not accurately controlled during clutch release, then clutch operation is simple, but driveline torque disturbances occur affecting drivability
Solution Approach 1:
The controller determines a desired engine acceleration profile before clutch release and commands engine torque to follow this profile in advance. This preliminary torque conditioning ensures that when the clutch is released, the engine is already positioned to minimize torque disturbances, improving driveline smoothness without complicating the clutch operation itself.
Solution Approach 2:
The system replaces direct mechanical clutch control with an electronic control system that manages engine torque. Instead of mechanically controlling the clutch release timing and characteristics, the system uses electronic torque commands to the engine, substituting mechanical complexity with electronic control precision to achieve smooth driveline transitions.
Data Source
AI summary
Systems and methods for learning torque estimate errors and updating torque estimation models are presented. In one example, torque errors are learned during an engine shut-down, after a disconnect clutch coupled between an engine and an electric machine has been released. An updated torque estimation model is then used to control torque during subsequent engine operation to improve drive feel and vehicle performance.