Fuel Injection Timing Detection via Pressure Waveform Analysis
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Solution Overview
Problem
Conventional fuel injection detecting devices face challenges in accurately determining the fuel-injection-start timing due to attenuated fuel pressure variations in common rails and noise interference, leading to erroneous detections, especially in multi-stage injections.
Innovation Solution
A fuel injection detecting device with a fuel pressure sensor placed in the fuel passage between an accumulator and the fuel injector, utilizing a falling pressure waveform to compute the fuel-injection-start timing, modeled by a straight line for reduced computation load and increased accuracy, and using a reference pressure to account for response delays and waveform disturbances.
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, but the fuel pressure variation is attenuated and detection accuracy is reduced
Solution Approach 1:
A transmission line is introduced as an intermediary component between the common rail and the fuel injector. The transmission line has a smaller volume than the common rail, which reduces the damping effect and allows fuel pressure variations to be transmitted more effectively to the sensor location, thereby improving detection accuracy without requiring direct sensor placement in the common rail
2Measurement precision
If a fuel pressure sensor is disposed in a fuel injector to detect fuel pressure before attenuation, then detection accuracy is improved, but the sensor installation becomes more complex and costly
Solution Approach 1:
The transmission line acts as a mediator that creates a dedicated pressure sensing pathway from the common rail to the sensor location. This allows the sensor to be positioned in a more accessible location (at the fuel injector or nearby) while still detecting the undamped pressure variations that occur in the common rail, thus improving both accessibility and accuracy
3Device complexity
If conventional detection methods are used with overlapping pressure waveforms from multi-stage injections, then the detection system remains simple, but erroneous detection of fuel-injection-start timing occurs
Solution Approach 1:
The invention extracts and analyzes only the falling waveform portion of the pressure signal for timing detection, separating this critical information from the overlapping pressure waveforms generated by multi-stage injections. By focusing on the distinctive falling edge characteristics rather than the entire pressure waveform, the system can reliably detect fuel injection start timing even when multiple injections overlap, without requiring complex signal processing or additional sensors
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
The solution enables accurate computation of fuel-injection-start timing with high precision, minimizing disturbances and errors, even in multi-stage injections, by stabilizing the reference pressure and using a mathematical model to analyze the falling pressure waveform.
Implementation Method 1
a fuel pressure sensor provided in a fuel passage fluidly connecting an 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
Implementation Method 2
the fuel injection detection device computes an actual fuel-injection-start timing based on a falling waveform of the fuel pressure during a period in which the fuel pressure decrease due to a fuel injection rate increase
Data Source
AI summary
A fuel injection detecting device computes an actual fuel-injection-start timing based on a falling waveform of the fuel pressure detected by a fuel sensor during a period in which the fuel pressure decreases due to a fuel injection rate increase. The falling waveform is modeled by a modeling formula. A reference pressure is substituted into the modeling formula, whereby a timing is obtained as the fuel-injection-start timing.