Variable Compression Ratio Engine Cylinder Calibration
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Solution Overview
Problem
Variable Compression Ratio (VCR) engines face challenges in accurately adjusting compression ratios due to manufacturing tolerances, leading to inefficiencies and performance losses, as existing calibration methods rely on average compression ratios rather than individual cylinder variations.
Innovation Solution
A method to optimize VCR engine calibration by quantifying the actual compression ratio of each cylinder and adjusting the VCR mechanism based on fuel flow and peak torque at different settings, using engine operating conditions to select the optimal compression ratio for fuel efficiency and performance, thereby minimizing fuel consumption and emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If VCR calibration is based on average compression ratio across all cylinders, then device complexity is reduced, but manufacturing precision is worsened due to significant part-to-part variation
Solution Approach 1:
The patent segments the calibration process by cylinder, measuring and calibrating the compression ratio of each individual cylinder separately rather than using an average value. This allows each cylinder to be optimized independently, accounting for manufacturing variations in the VCR mechanism components.
Solution Approach 2:
The patent implements a feedback mechanism where the actual compression ratio of each cylinder is measured during operation, and this measured value is used to update the calibration data. The controller uses this feedback to determine optimal spark timing and fuel injection parameters for each cylinder based on its specific compression ratio.
2Manufacturing precision
If expensive premium manufacturing methods and select fit parts are used, then manufacturing precision is improved to control CR differences, but device complexity increases
Solution Approach 1:
The patent enables the engine to self-calibrate by automatically measuring the actual compression ratio of each cylinder during operation and using this information to optimize its own performance parameters. This eliminates the need for expensive pre-manufacturing quality control processes while achieving equivalent or better results through operational adaptation.
3Use of energy by moving object
If higher compression ratio is used to improve thermal efficiency, then use of energy is improved, but reliability worsens due to knock-limited conditions over large portion of operating map
Solution Approach 1:
The patent dynamically adjusts the effective compression ratio for each cylinder based on real-time operating conditions and measured actual compression ratio. The controller modifies spark timing and fuel injection parameters adaptively, allowing the engine to operate at higher effective compression ratios when conditions permit (improving efficiency) while preventing knock when conditions require (maintaining reliability).
Data Source
AI summary
Methods and systems are provided for improving calibration of a variable compression ratio engine. Cylinder-to-cylinder compression ratio variations are detected and accounted for by comparing cylinder fuel flow and IMEP at each compression ratio setting. Dilution parameters including EGR and VCT schedule are also calibrated to account for the cylinder-to-cylinder compression ratio variations.