Fuel Injector Leakage Correction via Pressure Slope Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining fuel injection timing and quantity in internal combustion engines fail to accurately compensate for potential leakage effects in the fuel rail system, leading to inaccuracies in fuel quantity calculation.
Innovation Solution
A method that samples pressure signals in the crankshaft angular domain, filters the signals to reduce noise, calculates the total pressure difference and leakage pressure difference, and uses the injection pressure difference to determine the fuel quantity injected, thereby compensating for leakage effects without additional pressure measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fuel rail pressure is measured to determine fuel injection quantity, then timing and quantity can be calculated, but static errors caused by fuel leakages are not compensated leading to measurement inaccuracies
Solution Approach 1:
The pressure difference is segmented into two components: total pressure difference (measured) and leakage pressure difference (calculated through linear extrapolation). By separating these components, the method can compensate for leakage effects while maintaining the simplicity of single-pressure measurement.
Solution Approach 2:
The method performs preliminary action by calculating the linear pressure slope before the injection event and using it to predict the leakage pressure difference. This allows the system to pre-compensate for leakage effects rather than attempting to measure them directly during injection.
2Measurement precision
If additional pressure measurements are taken to account for leakage, then measurement accuracy improves, but system complexity and measurement time increase
Solution Approach 1:
The system uses its existing pressure measurement capability to serve dual purposes: measuring both the total pressure difference and the leakage pressure difference (through slope calculation). No additional pressure sensors or measurement devices are required, as the single pressure signal provides all necessary information.
Solution Approach 2:
The single pressure measurement system performs multiple functions: it measures the total pressure difference for fuel quantity calculation and simultaneously provides data for leakage detection through linear slope analysis. This multi-functionality eliminates the need for separate leakage measurement systems.
3Measurement precision
If pressure signals are sampled at high frequency to capture injection dynamics, then measurement precision improves, but signal noise increases requiring filtering
Solution Approach 1:
The method applies partial filtering that removes high-frequency noise while preserving the essential injection event characteristics. Rather than aggressive filtering that would smooth out important dynamics, the approach uses mild filtering sufficient to reduce noise but strong enough to maintain injection timing and pressure difference accuracy.
Data Source
AI summary
A method for operating a combustion engine is provided. A fuel injector is operated to perform a fuel injection, a sequence of pressure signals of the fuel rail pressure during the fuel injection is sampled and filtered and a total pressure difference between a first sample after a top dead center of the fuel pump and before the fuel injection has started and a chosen second sample after the injection and before a next pumping stroke is determined. A linear pressure slope at the second sample and a leakage pressure difference between the first sample and the second sample based on the linear pressure slope is calculated, leading to calculating an injection pressure difference as the difference between total pressure difference and the leakage pressure difference. With this, a value of a fuel quantity injected as a function of the injection pressure difference can be determined, while leakages are compensated.