Engine Stopping Position Control via Cylinder Event Spark Timing
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Solution Overview
Problem
Existing engine stopping methods often result in unpredictable engine restart times and increased emissions due to the inability to accurately control the crankshaft angle at which engine rotation ceases, especially without the assistance of an electric machine.
Innovation Solution
The method involves transitioning from adjusting spark timing based on engine load and speed to adjusting it based on the actual number of cylinder events after a recent engine stop request, allowing for more precise control of engine stopping position through spark timing adjustments responsive to the total number of cylinder events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fuel injection is delayed to improve engine stopping position, then engine stopping position control is improved, but engine stop time increases
Solution Approach 1:
The system dynamically adjusts spark timing based on the actual total number of cylinder events occurring after an engine stop request, rather than using fixed timing schedules. This allows the ignition system to adapt in real-time to the engine's deceleration characteristics, optimizing the balance between stopping position accuracy and stop time.
Solution Approach 2:
The controller monitors the actual total number of cylinder events (crankshaft rotations) after an engine stop request and uses this feedback to adjust spark timing. This closed-loop control enables the system to achieve precise stopping position control while minimizing stop time by responding to the engine's actual deceleration behavior.
2Device complexity
If conventional spark timing adjustment based on engine load and speed is used, then engine operation is simple, but engine stopping position is unpredictable
Solution Approach 1:
The system changes the controlling parameter for spark timing from engine load and speed to the actual total number of cylinder events after an engine stop request. This parameter change allows the system to directly control and predict engine stopping position, as the number of cylinder events directly correlates with crankshaft rotation and stopping angle.
3Loss of time
If fuel injection is ceased immediately upon stop request, then engine stop time is reduced, but engine stopping position cannot be controlled within desired crankshaft window
Solution Approach 1:
The system continues fuel injection for a predetermined number of cylinder events after the engine stop request is received, rather than ceasing injection immediately. This preliminary continuation of fuel injection allows the engine to complete additional power strokes that provide controlled deceleration, enabling the engine to stop within the desired crankshaft window while minimizing stop time.
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 improves engine starting efficiency, reduces emissions, and allows for more predictable and repeatable engine stopping, all while reducing fuel consumption and eliminating the need for additional hardware.
Implementation Method 1
a charge in a cylinder may be ignited via a spark that is timed responsive to an actual total number of cylinder events since a most engine stop request so that the ignited charge provides torque to continue engine rotation
Data Source
AI summary
Systems and methods for stopping rotation of an engine of a vehicle in a requested or desired crankshaft window are described. In one example, spark timing of one or more engine cylinders is adjusted responsive to an actual total number of cylinder events occurring after an engine stop request is generated.