Engine Restart Control via Variable Speed Threshold
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Solution Overview
Problem
Existing techniques for restarting an internal combustion engine after automatic stop do not adequately consider fluctuations in engine rotation speed, leading to slower restart times and inefficient cranking processes.
Innovation Solution
The method involves restarting the internal combustion engine by performing cranking when the rotation speed is lower than a predetermined first rotation speed, with the first rotation speed set differently based on the engagement or release of the lock-up clutch of the torque converter, allowing for quick restarts by considering the fluctuations in engine rotation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the first rotation speed is set high to enable quick restart by fuel supply only, then restart speed is improved, but the engine may fail to restart when rotation speed fluctuates below this threshold
Solution Approach 1:
The patent applies dynamics by making the first rotation speed threshold variable rather than fixed. The threshold is dynamically adjusted based on the lock-up clutch state of the torque converter: set higher when the clutch is released (greater speed fluctuations expected) and set lower when the clutch is engaged (smaller speed fluctuations expected). This dynamic adjustment allows the system to maintain reliable restart conditions across varying operational states while optimizing restart speed in each state.
Solution Approach 2:
The patent changes the parameter of the first rotation speed threshold based on the lock-up clutch state. By switching between two different threshold values depending on whether the clutch is engaged or released, the system adapts to different operational conditions, ensuring reliable restart while maximizing restart speed when conditions permit.
2Reliability
If cranking is always performed during restart, then restart reliability is improved, but restart time increases and productivity decreases
Solution Approach 1:
The patent applies partial action by selectively applying cranking only when necessary rather than always performing full cranking. When the engine rotation speed is above the first threshold, only fuel supply is restarted (partial action). When the rotation speed falls below the threshold, cranking is added (excessive action to ensure reliability). This selective approach minimizes unnecessary cranking operations while maintaining restart reliability, thereby improving overall restart efficiency and productivity.
Solution Approach 2:
The system uses feedback by continuously monitoring the engine rotation speed and comparing it against the first rotation speed threshold. Based on this feedback, the control system dynamically decides whether to perform cranking or rely on fuel supply alone, optimizing the balance between restart reliability and restart efficiency.
3Reliability
If the first rotation speed is set low to accommodate speed fluctuations, then restart reliability is improved, but quick restart capability is reduced
Solution Approach 1:
The patent resolves this contradiction through dynamic adjustment of the first rotation speed threshold based on the lock-up clutch state. When the clutch is engaged and speed fluctuations are minimal, a lower threshold is used, enabling quick restart by fuel supply only. When the clutch is released and fluctuations are larger, a higher threshold is used to maintain reliability. This dynamic approach minimizes restart time in stable conditions while preserving reliability in fluctuating conditions.
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 enables quicker restarts of the internal combustion engine by adjusting the restart method based on the engine's rotation speed fluctuations and the torque converter's lock-up clutch state, optimizing restart times and reducing unnecessary cranking.
Implementation Method 1
the greater the moment of inertia acting on the part rotated together with the crankshaft of the internal combustion engine, the smaller the fluctuations of the rotation speed of the internal combustion engine
Implementation Method 2
a lock-up clutch of a torque converter arranged between the internal combustion engine and a transmission is engaged
Implementation Method 3
cranking of the internal combustion engine is performed at the time of restarting the fuel supply
Implementation Method 4
restarting fuel supply to the internal combustion engine
Data Source
AI summary
In the case of restarting an internal combustion engine that has been automatically stopped during running, the internal combustion engine is restarted by combustion recovery starting when the rotation speed of the internal combustion engine under the input of a restart request is greater than or equal to a predetermined first rotation speed. In the case of restarting the internal combustion engine that has been automatically stopped during running, the internal combustion engine is restarted by cranking recovery starting when the rotation speed of the internal combustion engine under the input of the restart request is lower than the predetermined first rotation speed. The first rotation speed is set lower at the restart of the internal combustion engine in a sailing stop state than at the restart of the internal combustion engine in a coast stop state.