Engine Control Unit Crankshaft Stop Position Management
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Solution Overview
Problem
Internal combustion engines face challenges in preventing the crankshaft from stopping at the top dead center (TDC) during shutdown, which hinders ignition-based startup due to balanced friction and rotation inertia forces, especially in six-cylinder engines, making it difficult to achieve reliable restarts without external motor-generator assistance.
Innovation Solution
A control apparatus and method using an electronic control unit to manage fuel injection and ignition in the expansion stroke of a cylinder, predicting and adjusting the stop position of the crankshaft by retarding the exhaust valve opening timing and ensuring a recovery condition of in-cylinder pressure is met, allowing for normal running torque generation and avoiding TDC stops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the crankshaft stop position is controlled using a motor-generator to apply external force, then the stop position can be precisely controlled to avoid TDC, but the device complexity and cost increase
Solution Approach 1:
The invention uses the engine's own cylinders to control the crankshaft stop position. By selectively igniting or suppressing combustion in specific cylinders, the engine self-regulates the crankshaft position without external assistance. The cylinder that naturally would stop at TDC is detected, and combustion is suppressed in that cylinder while being executed in the preceding cylinder, allowing the crankshaft to pass through TDC and stop at a safe position.
Solution Approach 2:
The invention changes the combustion parameter (ignition timing or fuel injection) in specific cylinders to control crankshaft stop position. By suppressing combustion in the cylinder that would stop at TDC and executing combustion in the preceding cylinder, the torque characteristics are altered to ensure the crankshaft passes through TDC and stops at an intermediate position suitable for restart.
2Use of energy by moving object
If fuel injection and ignition are stopped completely during engine shutdown, then fuel efficiency improves, but the ability to control crankshaft stop position and enable ignition-based startup deteriorates
Solution Approach 1:
The invention performs preliminary detection of which cylinder would stop at TDC before complete shutdown. Based on this detection, it pre-arranges the combustion suppression strategy by suppressing fuel injection and ignition in the identified cylinder while maintaining combustion in the preceding cylinder. This preliminary preparation ensures that when shutdown occurs, the crankshaft is guided to a safe stop position and can be reliably restarted using ignition-based startup.
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 reliable ignition-based startup by preventing crankshaft stops at TDC, ensuring efficient engine restarts without the need for external motor-generator assistance, thereby enhancing engine performance and reducing the risk of insufficient torque generation.
Implementation Method 1
ignition-based startup for rotating a crankshaft through the generation of a normal running torque by explosion
Implementation Method 2
a relationship between potential energy resulting from the pumping action (the action of something like a spring based on the compression of air) and a rotation inertia force
Implementation Method 3
potential energy resulting from the pumping action (the action of something like a spring based on the compression of air)
Implementation Method 4
an exhaust valve has already been open or will open soon
Data Source
AI summary
A control apparatus for an internal combustion engine that can be a four-cycle engine including cylinders into which fuel is directly injected, the control apparatus includes an electronic control unit. The electronic control unit is configured to execute a fuel injection and an ignition for the cylinder in an expansion stroke on a condition that a stop of the piston in any one of the cylinders at vicinity of a top dead center after a compression stroke is predicted when the electronic control unit is configured to stop the fuel injection and the ignition for the internal combustion engine upon fulfillment of a predetermined stop condition.