Fuel Injection Timing Detection via Pressure Waveform Modeling
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Solution Overview
Problem
Existing fuel injection detection methods, particularly those using fuel pressure sensors in common rails, face challenges in accurately detecting fuel injection end timing due to attenuated pressure variations and potential noise interference, leading to erroneous timing detection.
Innovation Solution
A fuel injection detecting device is implemented with a fuel pressure sensor in the fuel passage connecting the accumulator and injector, computing the fuel injection end timing based on the rising waveform of pressure during fuel injection rate decrease, modeled using a mathematical or straight line model, and utilizing a reference pressure to enhance accuracy, especially in multi-stage injections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fuel pressure sensor is disposed in a common rail to detect fuel pressure variation, then the detection position is convenient and easy to implement, but the fuel pressure variation due to fuel injection is attenuated leading to low measurement precision
Solution Approach 1:
The patent introduces an intermediary approach by using a mathematical model to compute the fuel-injection-end timing from pressure waveform data, rather than directly detecting it with a sensor. This mediator (computational model) bridges the gap between the attenuated pressure signal in the common rail and the actual injection end timing, allowing accurate detection despite the sensor's limited position.
Solution Approach 2:
The patent transforms the detection approach by changing from direct timing detection to indirect computation based on pressure waveform parameters. By analyzing the differential values and zero-crossing points of the pressure waveform, the system extracts injection timing information through parameter transformation rather than direct measurement.
2Device complexity
If the fuel-injection-end timing is detected by identifying the zero-crossing point of differential pressure values, then the detection method is simple, but noise and waveform overlaps cause erroneous detection reducing reliability
Solution Approach 1:
The patent applies preliminary action by computing the differential values of the pressure waveform before attempting to identify the zero-crossing point. This preprocessing step prepares the data by highlighting the rate of change, making the subsequent zero-crossing detection more robust against noise and overlapping waveforms from multi-stage injections.
Solution Approach 2:
The system uses feedback by continuously monitoring the pressure waveform and its differential values, comparing them against expected patterns to identify the actual fuel-injection-end timing. The computational model adjusts for noise and overlapping waveforms by analyzing the feedback from the differential pressure signal.
3Measurement precision
If a mathematical model is used to compute fuel-injection-end timing from pressure waveform, then detection accuracy is improved, but computational load and memory requirements increase
Solution Approach 1:
The patent applies partial action by using a simplified mathematical model that computes only the necessary differential values and zero-crossing points, rather than performing a complete waveform analysis. This partial computation approach achieves sufficient accuracy for injection timing detection while minimizing computational energy consumption.
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 approach allows for precise and accurate detection of fuel injection end timing, reducing computational load and memory requirements while minimizing the impact of disturbances and waveform overlaps, thereby improving the reliability of fuel injection control.
Implementation Method 1
a fuel pressure sensor provided in a fuel passage fluidly connecting the accumulator and a fuel injection port of the fuel injector. The fuel pressure sensor detects a fuel pressure which varies due to a fuel injection from the fuel injection port
Data Source
AI summary
A fuel injection detecting device computes an actual fuel-injection-end timing based on a rising waveform of the fuel pressure detected by a fuel sensor during a period in which the fuel pressure increases due to a fuel injection rate decrease. The rising waveform is modeled by a modeling formula. A reference pressure Ps(n) is substituted into the modeling formula, whereby a timing “te” is obtained as the fuel-injection-end timing.