Crankshaft Stop Position Control for Fast Engine Restart
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Solution Overview
Problem
Restarting the engine may be required immediately after the automatic stop of the engine, and if the crankshaft rotating due to inertia stops at a position that deviates from the predetermined position, it may not be possible to immediately respond to a request for restarting the engine.
Innovation Solution
A vehicle control device that includes control means for controlling an engine and an electric motor to stop the crankshaft at a predetermined position using pre-brake and main brake controls, where the electric motor brakes the crankshaft's inertia-based rotation according to predetermined target transition information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine automatically stops at a traffic light to improve fuel efficiency, then energy saving is achieved, but the crankshaft may stop at a position that deviates from the predetermined position, making it difficult to restart immediately
Solution Approach 1:
The control device performs preliminary action by controlling the crankshaft to stop at a predetermined position (compression top dead center or near it) before the engine is automatically stopped. This ensures that when restart is needed, the crankshaft is already in the optimal position for immediate restart, eliminating the delay that would otherwise occur. The control device achieves this by adjusting the ignition timing and fuel injection timing to create a braking effect that positions the crankshaft correctly during the idle stop period.
Solution Approach 2:
The control device uses feedback from the crankshaft position sensor to monitor the actual position of the crankshaft and adjusts the ignition timing and fuel injection timing accordingly. This closed-loop control ensures that the crankshaft stops at the predetermined position even when inertia causes deviations. The control device continuously compares the actual position with the target position and makes real-time adjustments to maintain accurate positioning for reliable restart.
2Device complexity
If the crankshaft is allowed to stop freely due to inertia, then the system is simpler, but the crankshaft stops at unpredictable positions, preventing immediate engine restart
Solution Approach 1:
The control device replaces complex mechanical positioning mechanisms with electronic control of ignition and fuel injection timing. Instead of using mechanical brakes or positioners on the crankshaft, the system uses the combustion process itself to create a controlled braking effect that positions the crankshaft. This substitution maintains simplicity while achieving precise position control, allowing the crankshaft to stop at the predetermined position without adding mechanical complexity.
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
The crankshaft is accurately stopped at a predetermined position, reducing the frequency of subsequent position adjustments and enabling quick restartability of the engine, even if restarting is required immediately after automatic stop.
Implementation Method 1
stop position control for braking the crankshaft (30a) rotating due to inertia by a driving force of the electric motor (34)
Data Source
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AI summary
A vehicle control device (10) which includes control means (11) for controlling an engine (30) mounted on a vehicle (100) and an electric motor (34) that enables a crankshaft (30a) of the engine (30) to rotate is provided. When an idle stop condition is satisfied, the control means (11) executes: automatic stop of the engine (30); and stop position control for braking the crankshaft (30a) rotating due to inertia by a driving force of the electric motor (34) so as to stop the crankshaft (30a) at a predetermined position (P). The stop position control includes: pre-brake control for controlling the electric motor (34) such that a rotation speed of the crankshaft (30a) decreases according to predetermined target transition information (Tne); and main brake control for controlling the electric motor such that the crankshaft (30a) is stopped at the predetermined position (P) after the pre-brake control.