Spark Timing Control via Burn Duration for Engine Transients
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Solution Overview
Problem
Existing engine control systems face challenges in optimizing spark timing during transient conditions, leading to fuel economy losses, poor combustion stability, and engine knock, especially when intake and exhaust cam phasers are adjusted significantly from their calibrated positions.
Innovation Solution
A model-based approach that determines laminar flame speed and 0-50 burn duration to adjust spark timing, considering measured intake and exhaust cam phaser positions, thereby improving fuel economy and combustion stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spark timing is adjusted based on traditional calibration maps during transient conditions, then engine torque control is maintained, but fuel economy deteriorates and combustion stability deteriorates
Solution Approach 1:
The system changes the control parameter from fixed calibration maps to dynamically calculated burn duration based on real-time flame speed measurements. By continuously adjusting spark timing according to actual combustion characteristics rather than predetermined values, the system achieves both torque control and fuel economy improvement during transient conditions
Solution Approach 2:
The system implements feedback by measuring actual burn duration and flame speed, then using this information to adjust spark timing for subsequent cycles. This closed-loop control enables the engine to adapt to changing conditions while maintaining optimal combustion efficiency and torque output
2Adaptability or versatility
If cam phasers are adjusted significantly from calibrated positions, then adaptability to different operating conditions improves, but combustion stability deteriorates and knock increases
Solution Approach 1:
The system uses real-time burn duration measurements as feedback to monitor combustion stability. When cam phasers are adjusted to extreme positions, the feedback mechanism detects changes in combustion characteristics and provides data to adjust spark timing accordingly, preventing knock and maintaining stability across a wider range of operating conditions
Solution Approach 2:
The system transitions from static calibration maps to dynamic spark timing adjustment based on real-time combustion measurements. This allows the engine to adaptively respond to cam phaser position changes and maintain stable combustion even when operating outside calibrated positions
3Ease of operation
If traditional spark timing control is used during transient conditions, then engine operation is simplified, but knock increases requiring additional spark timing adjustments
Solution Approach 1:
The system enables the engine to self-adjust spark timing based on its own combustion characteristics. By measuring burn duration and flame speed internally and using this information to prevent knock, the system eliminates the need for complex external calibration adjustments while reducing harmful knock events
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 enhances fuel economy, provides more flexibility in adjusting cam phaser positions, and reduces the need for spark timing adjustments to prevent knock, making the calibration of knock prevention systems easier.
Implementation Method 1
In spark-ignition engines, spark initiates combustion of an air/fuel mixture provided to the cylinders
Data Source
AI summary
A system according to the principles of the present disclosure includes a first burn duration module and a spark control module. The first burn duration module determines a first duration of at least a portion of a fuel burn within a cylinder of an engine from a first time when a first predetermined percentage of a mass of fuel within the cylinder is burned to a second time when a second predetermined percentage of the fuel mass is burned. The spark control module controls a spark plug to adjust spark timing of the cylinder based on the first burn duration.