Intake Tract Coking Detection via Lambda Deviation Tests
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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 efficiency.
Innovation Solution
A method involving an engine test unit that performs two quantity deviation tests using the variable inlet valve lift controller and throttle flap to objectively assess air ratio values, allowing for fault detection without disassembly, including coking identification, by comparing air ratio values measured during different load control operations.
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 detection is subjective
Solution Approach 1:
The patent replaces the mechanical disassembly-based visual inspection system with an electronic measurement system. The engine control unit performs automated lambda value measurements during quantity deviation tests, substituting manual visual inspection with electronic sensing and computational analysis to detect coking objectively without engine disassembly.
Solution Approach 2:
The engine's own control system (engine control unit) performs the diagnostic function using its existing sensors and actuators. The system utilizes the engine's throttle flap and injection system to conduct quantity deviation tests, allowing the engine to self-diagnose coking conditions without requiring external inspection tools or disassembly.
2Reliability
If engine disassembly is performed for visual inspection, then coking can be observed, but diagnostic time and working effort increase significantly
Solution Approach 1:
The patent performs preliminary diagnostic measurements by conducting quantity deviation tests using existing engine operations before any disassembly is considered. The system proactively measures lambda values under controlled throttle conditions to detect coking early, preventing the need for time-consuming disassembly and visual inspection.
3Measurement precision
If automated measurement method is used, then objective assessment is achieved, but the method only works with phase adjustment of valve opening times
Solution Approach 1:
The patent creates a universal diagnostic method that works with different engine control systems by utilizing the throttle flap as the common control element. The quantity deviation test methodology can be applied whether the engine uses variable valve timing, variable valve lift, or traditional throttle-based load control, making the diagnostic approach adaptable to multiple engine architectures.
Data Source
AI summary
A method detects a fault, in particular coking, in the intake tract of an internal combustion engine with direct fuel injection, a throttle valve, and a variable intake valve lift controller. The method has the steps of a) carrying out a first quantity deviation test, by which a first air ratio value is ascertained that is formed from a lambda value, which is measured during the first quantity deviation test, and a desired lambda value of the fuel combustion in the fuel chambers of the internal combustion engine, wherein in the first quantity deviation test, a load control is carried out by the variable intake valve lift controller; b) carrying out a second quantity deviation test, by which a second air ratio value is ascertained that is formed from a lambda value, which is measured during the second quantity deviation test, and a desired lambda value of the fuel combustion in the fuel chambers of the internal combustion engine, wherein in the second quantity deviation test, a load control is carried out by the throttle valve; and lastly c) determining a comparison result from the first air ratio value and the second air ratio value, the presence of a fault in the intake tract of the internal combustion engine being detectable using the comparison result.