Engine Stop Position Prediction for Reliable Restart
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Solution Overview
Problem
Internal combustion engines face challenges in accurately predicting the stop position, leading to insufficient fuel diffusion and potential spontaneous ignition due to varying conditions and engine deterioration, resulting in undesirable vibrations and poor restart performance.
Innovation Solution
An internal combustion engine system with a rotation speed measurement unit and stop position prediction module predicts the stop position based on measured rotation speed, allowing for precise fuel injection timing and increased intake air, ensuring adequate fuel distribution and preventing spontaneous ignition by controlling fuel injection and ignition timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fuel injection is performed immediately before engine stop to enable quick restart, then restart speed is improved, but fuel diffusion becomes insufficient leading to poor combustion
Solution Approach 1:
The system performs preliminary action by injecting fuel into the cylinder before the engine stops, specifically targeting the cylinder that will be in the appropriate stroke range (intake to compression) at stop. This advance fuel injection ensures that fuel is already present and can diffuse adequately even though the engine stops shortly after, resolving the contradiction between quick restart and sufficient fuel diffusion.
2Reliability
If fuel injection timing is advanced to ensure adequate compression for ignition, then combustion reliability is improved, but the cylinder may pass over top dead center causing spontaneous ignition and vibrations
Solution Approach 1:
The system uses feedback by continuously monitoring engine rotation speed and predicting the stop position based on measured values. The stop position prediction module calculates which cylinder will be in the appropriate stroke range at stop, and this information feeds back to control the fuel injection timing and selection, preventing both missed combustion and spontaneous ignition.
Solution Approach 2:
The system changes parameters by dynamically adjusting fuel injection timing and selection based on the predicted stop position. Instead of using fixed timing, the system modifies injection parameters in real-time according to engine deceleration characteristics, ensuring optimal combustion conditions without causing spontaneous ignition.
3Manufacturing precision
If stop position prediction is performed to enable accurate fuel injection, then fuel injection precision is improved, but measurement accuracy becomes insufficient due to engine deterioration and varying conditions
Solution Approach 1:
The system measures actual engine rotation speed during deceleration and uses this feedback to predict the stop position. By basing predictions on real-time measured values rather than theoretical calculations, the system compensates for engine deterioration and varying conditions, maintaining high prediction accuracy despite changes in engine characteristics over 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
The system achieves high accuracy in predicting the stop position, ensuring quick engine restart with sufficient fuel injection and preventing undesirable vibrations, thereby improving engine reliability and performance.
Implementation Method 1
a rotation speed measurement unit that measures rotation speed of the internal combustion engine
Implementation Method 2
a stop position prediction module that predicts a stop position of the internal combustion engine, based on the rotation speed of the internal combustion engine measured by the rotation speed measurement unit when one of multiple cylinders of the internal combustion engine passes over a top dead center during a decrease in rotation speed
Implementation Method 3
a fuel injection unit that is capable of individually injecting a supply of fuel into the multiple cylinders of the internal combustion engine
Implementation Method 4
an ignition unit that is capable of individually igniting an air-fuel mixture of the intake air and the injected fuel in the multiple cylinders of the internal combustion engine
Implementation Method 5
an air intake regulation unit that regulates an amount of intake air into the internal combustion engine
Implementation Method 6
a crank angle measurement unit that measures a crank angle of the internal combustion engine
Data Source
AI summary
The internal combustion engine control technique of the invention computes a TDC pass rotation speed Ntdc, which represents the rotation speed of an engine when one of multiple cylinders of the engine passes over a top dead center TDC (step S110). The control technique estimates an engine stop crank angle CAs from a map that is experimentally or otherwise obtained to represent a variation in TDC pass rotation speed Ntdc against the stop position of the engine (step S120), and specifies a fuel injection cylinder that stops in a preset cycle range including part of a compression stroke at a stop of the engine (step S130). The specified fuel injection cylinder receives lean fuel injection at a specific fuel injection timing (step S170). When the specified fuel injection cylinder is later presumed not to pass over a top dead center TDC of the compression stroke, a corrected amount of fuel is injected into the specified fuel injection cylinder (step S240). When the specified fuel injection cylinder is later presumed to pass over the top dead center TDC of the compression stroke, on the other hand, the control technique ignites an air-fuel mixture of the intake air and the injected fuel for combustion in the compression stroke, synchronously with fuel injection into a next cylinder that goes into the compression stroke after the specified fuel injection cylinder (step S270).