VCR Engine Misfire Detection via Volumetric Energy Release
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Solution Overview
Problem
Existing internal combustion engines with variable compression ratio (VCR) face challenges in detecting combustion losses, particularly misfires, which occur when the compression ratio becomes too low, especially under conditions like cold starts or low load, due to component dimensional dispersion and tolerance issues.
Innovation Solution
A method for detecting misfires in VCR engines using a single pressure sensor to measure pressure in the combustion chamber, calculating the volumetric release of energy as a function of pressure and crankshaft angle, and comparing it with a predefined threshold throughout an engine cycle to identify potential misfires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the compression ratio is increased to improve power and reduce emissions under light load, then power delivery and emission performance are improved, but knocking phenomenon occurs which is detrimental to engine operation
Solution Approach 1:
The patent employs a knock detection system that provides real-time feedback to the compression ratio control system. When knocking is detected, the system adjusts the compression ratio downward to eliminate the knock, and when no knock is present, it increases the compression ratio to maximize power output. This closed-loop feedback mechanism enables dynamic optimization of the compression ratio based on actual engine conditions.
Solution Approach 2:
The patent dynamically changes the compression ratio parameter based on engine operating conditions and knock detection results. By continuously adjusting this critical parameter, the system optimizes the balance between power output and knock prevention, allowing the engine to operate at the highest possible compression ratio without inducing knocking under various load and speed conditions.
2Object-affected harmful factors
If the compression ratio is decreased to prevent knocking, then knocking is avoided, but loss of combustion (misfire) occurs under critical conditions such as cold start or low load
Solution Approach 1:
The patent uses a misfire detection system that monitors combustion quality and provides feedback to the compression ratio control. When misfire is detected, the system reduces the compression ratio to prevent combustion loss. This feedback mechanism allows the system to maintain reliable combustion by adapting the compression ratio to prevailing conditions such as cold starts or low load operations.
Solution Approach 2:
The patent implements dynamic adjustment of the compression ratio based on real-time detection of combustion quality. Rather than using a fixed compression ratio, the system continuously adapts the compression ratio to maintain optimal combustion reliability across varying operating conditions, preventing misfire when conditions are unfavorable while still enabling high compression operation when conditions permit.
3Device complexity
If a single pressure sensor is used to detect misfire, then device complexity is reduced, but measurement precision and reliability of misfire detection are compromised
Solution Approach 1:
The patent transforms the pressure signal by calculating the volumetric release of energy (dQ/dV) as a function of crankshaft angle. This parameter transformation amplifies the combustion peak and enhances the contrast between successful combustion and misfire conditions, thereby improving detection precision with a single sensor. The transformation converts pressure data into a more discriminative metric for misfire detection.
Solution Approach 2:
The patent introduces a new dimension to the analysis by transforming the pressure-time signal into a volumetric energy release versus crankshaft angle representation. This dimensional transformation reorganizes the data to emphasize combustion characteristics, making misfire detection more reliable with a single pressure sensor by highlighting the combustion peak in a different parameter space.
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 method effectively detects misfires by amplifying the combustion peak and reducing noise, allowing for accurate thresholding and enabling robust control of VCR engines to maintain optimal compression ratios, preventing engine inefficiencies and emissions.
Implementation Method 1
a sensor capable of measuring the pressure in said chamber
Implementation Method 2
combustion chamber and a sensor capable of measuring the pressure in said chamber
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
The method involves measuring pressure in a combustion chamber (2), and calculating an energy release volume. The energy release volume is compared with a predefined threshold during an internal combustion engine cycle. A combustion loss of an internal combustion engine (1) is detected when the energy release volume remains lower than the predefined threshold during the entire engine cycle, where the threshold is determined based on an operating point of the engine.