Engine Stop Control Device Torque Trajectory Management
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Solution Overview
Problem
Existing engine stop control devices struggle to accurately control the engine rotation stop position due to variations in engine rotation behavior, particularly influenced by compression and friction, which are difficult to separately learn and account for.
Innovation Solution
An engine stop control device with a reference point target rotation speed setting, target trajectory calculating, and stop controlling sections, which sets a target trajectory extending to a reference point preceding the stop position, controlling torque to conform engine rotation behavior to the target trajectory, and adjusts torque control to manage energy deviations and friction learning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the target trajectory is calculated without considering compression influence, then the calculation is simple, but the accuracy of the target trajectory worsens
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compression torque values in a map for different crank angle ranges before actual engine stop control is needed. This allows the ECU to quickly retrieve and apply compression correction values during engine stop without performing complex real-time calculations, thus maintaining both simplicity and accuracy.
Solution Approach 2:
The patent changes the parameter representation by dividing the crank angle range into multiple sections and creating separate compression torque maps for each section. This allows the system to select the appropriate compression correction based on the current crank angle position, improving accuracy without requiring a single complex universal calculation model.
2Measurement precision
If friction and compression are learned separately from stop position error, then the learning accuracy improves, but it becomes difficult to learn them separately
Solution Approach 1:
The patent segments the stop position error into two distinct components: friction-related error and compression-related error. By identifying the crank angle position where compression occurs and attributing errors in that range to compression while attributing other errors to friction, the system can separately learn and compensate for each factor without them being mixed together.
Solution Approach 2:
The patent uses feedback by continuously monitoring the stop position error and using it to update both friction and compression learning values. The system feeds back the actual stop position compared to the target position and adjusts the learned friction and compression torques accordingly, enabling separate learning through iterative correction.
3Device complexity
If the alternator load control is rough with preset maps, then the control is simple, but the variation in engine rotation behavior cannot be sufficiently compensated
Solution Approach 1:
The patent applies dynamics by transitioning from static preset maps to dynamic target trajectory calculation. Instead of using fixed alternator load values from maps, the system calculates a dynamic target rotation speed trajectory based on current engine conditions, friction, and compression values, allowing the alternator load to be continuously adjusted to follow the optimal path to the target stop position.
Solution Approach 2:
The patent replaces the mechanical approach of using preset alternator load maps with a computational approach that calculates target rotation speed trajectories. This substitution allows for more precise control by using mathematical models of friction and compression to determine the optimal alternator torque profile, rather than relying on coarse mechanical map-based control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for accurate control of engine rotation behavior and stop position, reducing errors and improving restarting performance by efficiently managing torque and friction during the engine stop process.
Implementation Method 1
an engine stop control device... having a function to control an engine rotation stop position... torque of an electric machinery
Data Source
AI summary
Target rotation speed at a reference point set at TDC slightly preceding a target stop position of engine rotation is set. A target trajectory of an engine rotation behavior extending since an engine rotation stop behavior starts until the target rotation speed at the reference point is reached is calculated based on the target rotation speed at the reference point and an engine friction. Torque of an alternator is controlled to conform the engine rotation behavior to the target trajectory during the engine rotation stop behavior. Generation of the torque of the alternator stops at a position preceding the reference point by a predetermined crank angle. Therefore, the torque of the alternator is controlled such that an energy deviation between the target trajectory and the engine rotation behavior becomes zero at the position preceding the reference point by the predetermined crank angle.