Internal Combustion Engine Idle Stop Control via Air Intake and Electric Motor
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Solution Overview
Problem
Existing idle stop control methods for internal combustion engines face challenges in applying sufficient reverse torque during low engine speeds, leading to potential vibration issues when passing through resonance bands, as power generation in motor generators is limited at low speeds.
Innovation Solution
The method involves restarting the engine by resuming fuel injection if the engine speed is above a predetermined threshold and using an electric motor to rotate the crankshaft if below the threshold, while reducing air intake to minimize compression reaction force and vibration, and controlling the throttle valve to adjust air intake based on engine speed to manage resonance band passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If reverse torque is applied by motor generator during low engine speed, then the speed at which engine speed drops is increased, but power generation in motor generator is hardly possible at low speeds
Solution Approach 1:
The control device applies reverse torque to the crankshaft before the engine speed reaches the resonance band, preliminarily accelerating the speed drop to ensure the engine speed quickly passes through the resonance band where vibration occurs. This preliminary action prevents prolonged exposure to resonant frequencies.
Solution Approach 2:
The control device changes the operating parameters of the motor generator based on engine speed conditions. At low speeds where power generation is difficult, it switches to power driving mode to apply reverse torque, while at higher speeds it can utilize regenerative power generation, thus adapting to the changing power availability across different speed ranges.
2Object-affected harmful factors
If engine speed passes through resonance band quickly, then vibration is minimized, but sufficient reverse torque cannot be applied at low speeds
Solution Approach 1:
Reverse torque is applied in advance before the engine speed enters the resonance band, accelerating the speed drop rate proactively. This ensures that even though reverse torque application is limited at low speeds, the engine speed has already been sufficiently reduced by the time it reaches the resonance band, minimizing vibration exposure.
Solution Approach 2:
The control strategy aims to rush through the resonance band as quickly as possible by applying maximum available reverse torque at higher speeds and maintaining reduced air intake at lower speeds, thereby minimizing the time spent in the harmful resonance frequency range where vibration occurs.
3Object-affected harmful factors
If air intake is reduced when engine speed falls below threshold, then compression reaction force is reduced and vibration is minimized, but engine restart preparation is affected
Solution Approach 1:
The control device performs preliminary actions by gradually reducing air intake as engine speed approaches the threshold, and completes the air intake reduction when speed falls below the threshold. This staged approach allows the system to prepare for vibration minimization while maintaining enough air intake to support potential restart needs.
Solution Approach 2:
The air intake control is made dynamic and adaptive based on real-time engine speed conditions. The throttle valve opening is adjusted continuously according to engine speed, allowing the system to optimize the balance between vibration reduction and restart preparation capability as operating conditions change.
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 ensures efficient engine restart and minimizes vibration by optimizing air intake and using electric assistance, effectively reducing the time to pass through resonance bands and ensuring smooth operation.
Implementation Method 1
the internal combustion engine is started by causing a crankshaft to rotate using an electric motor
Implementation Method 2
compression reaction force can be reduced and fluctuation in the rotation of the internal combustion engine can be minimized by reducing the amount of air entering the cylinders
Data Source
AI summary
In an internal combustion engine, fuel injection is stopped to automatically stop the engine when automatic stop conditions are met. The engine is started in response to a request to restart the engine while an engine speed is decreasing due to an automatic stoppage by resuming fuel injection if the engine speed is equal to or greater than a combustion recoverable rotational speed threshold, and by using an electric motor if the engine speed is less than the combustion recoverable rotational speed threshold. When the engine speed of the internal combustion engine falls below the combustion recoverable rotational speed threshold while the engine speed is decreasing due to an automatic stoppage, an amount of air entering cylinders is reduced to be less than before the engine speed fell below the combustion recoverable rotational speed threshold.