Engine Injector Absolute Quantity Determination via Run-Up Speed Analysis
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Solution Overview
Problem
Current diagnostic methods for determining injection quantity errors in combustion engine injectors cannot accurately determine the absolute injection quantity, leading to uncertainty about which injectors need replacement, especially in multi-cylinder engines.
Innovation Solution
A method that uses a predeterminable engine-specific factor stored in the engine control unit or diagnostic tester to determine the absolute total and individual injection quantities by analyzing measurement data from run-up tests, including engine speed profiles during active and inactive injection phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If relative injection quantity comparison is used during run-up test, then diagnostic capability is improved, but absolute injection quantity determination remains impossible
Solution Approach 1:
The patent introduces an engine-specific factor f as an intermediary parameter that connects the measurable engine speed drop to the absolute injection quantity. This factor serves as a mediator that translates relative speed measurements into absolute injection quantities without requiring direct measurement of the injection itself.
Solution Approach 2:
The patent changes the measurement parameter from direct injection quantity measurement to engine speed drop measurement during free-fall phase. By measuring the speed drop rate instead of directly measuring injection quantity, the system can determine absolute injection quantities through calculation using the engine-specific factor.
2Ease of operation
If injector replacement decisions are made without absolute injection quantity data, then diagnostic process is simplified, but incorrect replacement decisions may occur
Solution Approach 1:
The patent replaces the need for complex direct injection measurement systems with a simpler computational approach using engine speed measurements and predefined factors. This substitution maintains reliability by using mathematical relationships rather than complex physical measurement systems.
3Device complexity
If torque requirement is unknown during run-up test, then test setup is simplified, but absolute injection quantity cannot be determined
Solution Approach 1:
The patent extracts the torque requirement determination from the direct measurement process by using the engine speed drop during free-fall phase as an indicator. Instead of measuring torque directly, the method extracts injection quantity information from the speed decay characteristics.
Data Source
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AI summary
Method for determining the absolute fuel injection quantity of the injectors (31) of an internal combustion engine with a cylinder number nz, wherein the average absolute injection quantity minj of the injectors (31) is determined on the basis of measurement data acquired during a run-up test in which all the cylinders of the engine are active and a predetermined engine-specific factor f(nz), which is proportional to the moment of inertia of the engine when all the cylinders are active, and wherein the measurement data are essentially suitable for describing the time profile of the engine speed n(t) during the run-up test, in particular a maximum achieved engine speed nmax, a first rate of change a1 of the engine speed during the running up with the injection system active, a second rate of change a2 of the engine speed with the injection system inactive and an idling speed nidle of the engine.