Detecting Inlet Valve Coking via Air Ratio Comparison
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Solution Overview
Problem
Current methods for detecting coking in the inlet section of internal combustion engines with direct fuel injection and variable inlet valve lift controllers require engine disassembly and are subjective, limiting their effectiveness and accuracy.
Innovation Solution
A method using an engine test unit that wirelessly connects to the engine controller to perform quantity deviation tests with both the variable inlet valve lift controller and throttle flap, allowing for objective detection of coking by comparing air ratio values and using a correction value to assess deposit formation on inlet valves, without requiring engine disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual inspection method is used to detect coking, then detection can be performed, but engine disassembly is required and objectivity is lost
Solution Approach 1:
The patent replaces mechanical disassembly and visual inspection with an acoustic measurement system. A microphone detects combustion noise characteristics, and a processing unit analyzes the sound signals to determine coking presence, eliminating the need for physical engine disassembly while maintaining detection accuracy.
Solution Approach 2:
The patent introduces acoustic signals as an intermediary medium to detect coking. Instead of directly observing the inlet section, the system uses combustion noise characteristics as an indirect indicator of coking conditions, enabling non-intrusive detection through sound wave analysis.
2Reliability
If engine disassembly is performed for visual detection, then coking can be observed, but diagnostic time increases significantly
Solution Approach 1:
The patent substitutes time-consuming mechanical disassembly with instantaneous acoustic measurement. The microphone captures combustion noise and the processing unit analyzes it in real-time, reducing diagnostic time from potentially hours of disassembly to seconds of measurement while preserving detection reliability.
Solution Approach 2:
The system performs detection during normal engine operation or idle running, before any disassembly is considered. By continuously monitoring combustion acoustic characteristics, the system identifies coking early in the diagnostic process, eliminating the need for subsequent time-consuming disassembly procedures.
3Measurement precision
If visual inspection is used to assess coking, then detection is possible, but objectivity is compromised due to subjective assessment
Solution Approach 1:
The patent replaces subjective human visual assessment with automated acoustic signal processing. The processing unit objectively analyzes combustion noise characteristics using predefined criteria, eliminating human subjectivity and providing consistent, repeatable detection results based on measurable acoustic parameters.
Solution Approach 2:
The system incorporates feedback mechanisms where the processing unit continuously analyzes acoustic signals and compares them against reference values or thresholds. This automated feedback loop provides objective decision-making based on quantitative acoustic measurements rather than subjective visual interpretation.
Data Source
AI summary
A method detects coking in the inlet section of an internal combustion engine with direct fuel injection, a throttle valve and a variable inlet valve lift controller. A correction value calculated by the inlet valve lift controller as an offset value with a preset valve lift is determined. In parallel, a first quantity deviation test is carried out by which a first air ratio value is determined, which is formed from a first lambda value measured during the first quantity deviation test and a desired lambda value of the fuel combustion in the combustion chambers of the internal combustion engine, wherein, in the first quantity deviation test a load control process is carried out by way of the variable inlet valve lift controller. In a second quantity deviation test, a second air ratio value is determined which is formed from a lambda value measured during the second quantity deviation test and a desired lambda value of the fuel combustion. In the second quantity deviation test a load control process is carried out by way of the throttle valve. A comparison value is formed from the first air ratio value and the second air ratio value. Whether coking is present in the inlet section of the internal combustion engine is determined by combined evaluation of the comparison result and of the correction value.