Fuel Injection Timing Detection Using Pressure Waveform Modeling
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Solution Overview
Problem
Existing fuel injection detecting devices struggle to accurately detect the maximum-fuel-injection-rate-reach (MFIRR) timing and fuel-injection-rate-decrease-start (FIRDS) timing due to attenuated fuel pressure variations in common rail systems and noise disturbances, especially during multi-stage injections.
Innovation Solution
A fuel injection detecting device with a fuel pressure sensor placed in the fuel passage between the accumulator and the injector, using falling and rising waveforms to compute changing timings, and employing modeling functions to determine intersection pressures and timings, thereby reducing disturbance effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fuel pressure sensor is disposed in a common rail to detect fuel pressure variation, then the detection structure is simple, but the measurement precision deteriorates because the fuel pressure variation is attenuated in the common rail
Solution Approach 1:
The patent introduces an accumulator as an intermediary component between the common rail and the fuel injector. The fuel pressure sensor is disposed in the accumulator to detect fuel pressure variation. The accumulator serves as a mediator that amplifies the fuel pressure variation signal while isolating the sensor from the high-pressure common rail environment, thus resolving the contradiction between simple sensor installation and accurate pressure variation detection.
2Measurement precision
If a fuel pressure sensor is disposed in a fuel injector to detect variation before attenuation, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The accumulator acts as an intermediary that captures the fuel pressure variation signal at its peak (when the injector needle is fully lifted) and holds it for detection. This allows the sensor to be installed in the accumulator rather than directly in the injector, reducing device complexity while maintaining measurement precision.
3Device complexity
If conventional detection methods are used with noise disturbances, then the detection system is simple, but the measurement precision deteriorates during multi-stage injections
Solution Approach 1:
The patent employs a feedback mechanism where the detected fuel pressure variation waveform is analyzed to identify specific characteristic points (maximum fuel injection rate reach timing and fuel injection rate decrease start timing). The system uses the waveform feedback to correct and refine the timing detection, eliminating the need for complex noise filtering while maintaining high measurement precision during multi-stage injections.
Solution Approach 2:
The system performs preliminary detection of the fuel pressure variation waveform and identifies characteristic points before final timing determination. By preliminarily analyzing the waveform shape and pressure variation pattern, the system prepares the data for accurate MFIRR and FIRDS timing calculation, reducing the impact of noise disturbances.
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 accurate detection of MFIRR and FIRDS timings with high precision, even in conditions with noise or multi-stage injections, by stabilizing the waveforms and correlating them with fuel injection rates.
Implementation Method 1
a fuel pressure sensor which detects a fuel pressure in the fuel passage, and varies according to a fuel injection
Data Source
AI summary
A fuel injection detecting device computes a maximum-fuel-injection-rate-reach timing and a fuel-injection-rate-decrease-start timing based on a falling waveform of the fuel pressure and a rising waveform of the fuel pressure. The falling waveform represents 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 represents the fuel pressure detected by the fuel sensor during a period in which the fuel pressure decreases due to a fuel injection rate increase. The rising waveform and the falling waveform are respectively modeled by modeling function. In a case of small fuel injection quantity, an intersection timing at which lines expressed by the modeling functions intersect with each other is defined as the maximum-fuel-injection-rate-reach timing and the fuel-injection-rate-decrease-start timing.