Cylinder-Specific Combustion Control for Engine Tolerance Variation
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Solution Overview
Problem
Existing methods for operating internal combustion engines with multiple cylinders fail to account for individual cylinder differences in parameters like air filling, deposits, wear, and mechanical tolerances, leading to inefficiencies and uneven emissions, which can result in overall engine efficiency losses due to global NOx emission constraints.
Innovation Solution
A method where each cylinder has a specific setpoint for combustion parameters, such as fuel quantity and ignition timing, adjusted based on its individual characteristics, using a cylinder-specific offset calculated from deviations in parameters like pressure, air mass, combustion center, and ignition delay, to ensure consistent emissions and efficiency across all cylinders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If global control of combustion parameters is used for all cylinders, then the control system is simple and easy to operate, but individual cylinder differences in parameters like air filling, deposits, wear, and mechanical tolerances are not accounted for, leading to uneven emissions and efficiency losses
Solution Approach 1:
The control system is segmented into cylinder-specific control loops, where each cylinder has its own setpoint for combustion parameters based on individual characteristics. The control variable for each cylinder is determined independently rather than using a single global control variable for all cylinders, allowing each cylinder to be optimized individually while maintaining overall system coordination.
2Reliability
If individual cylinder control is implemented to account for cylinder-specific differences, then emissions and efficiency are optimized for each cylinder, but the control system complexity increases
Solution Approach 1:
Each cylinder is assigned a local quality characteristic through its own setpoint value for the control variable. The setpoint for each cylinder is determined based on that cylinder's specific parameters (air filling, deposits, wear, mechanical tolerances), allowing localized optimization without requiring complete redesign of the overall control architecture. The control variable is adjusted locally for each cylinder while maintaining global coordination.
3Productivity
If cylinder-specific setpoints are used to optimize individual cylinder performance, then overall engine efficiency is improved, but the system requires more complex measurement and control mechanisms
Solution Approach 1:
The system employs feedback mechanisms where the actual control variable values for each cylinder are measured and compared against the cylinder-specific setpoints. Based on this feedback, the control variable is adjusted for each individual cylinder to achieve the desired performance targets. This feedback loop enables continuous optimization of each cylinder's performance while accounting for individual variations.
Data Source
Figure 1~2
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AI summary
The method involves acquiring specific cylinder signal from each cylinder (2). The combustion parameter of the corresponding cylinder is controlled as a function of the cylinder signal. The cylinder-specific reference cylinder value is set for the cylinder signal for each cylinder. The combustion parameter of the cylinder is adjusted as a function of the deviation of the cylinder signal from the reference cylinder value, such that reference cylinder value is tracked by cylinder signal.