Fuel Injection Rate Detection Using 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 the maximum fuel injection rate due to attenuated pressure variations and noise interference, especially during multi-stage injections.
Innovation Solution
A fuel injection detecting device with a fuel pressure sensor placed in the fuel passage connecting the accumulator and injector, which computes the maximum fuel injection rate based on both falling and rising pressure waveforms, using modeling functions to stabilize the measurement and account for reference pressures, thereby reducing disturbance and improving accuracy.
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 fuel injection system and the common rail. The fuel pressure sensor is disposed in the accumulator to detect fuel pressure variation before it is attenuated by the common rail. The accumulator acts as a mediator that preserves the pressure signal strength while still allowing detection of injection-induced variations.
2Device complexity
If fuel pressure detection is used to compute maximum fuel injection rate, then the detection method is simple, but the measurement precision deteriorates due to noise interference and overlapping pressure waveforms during multi-stage injections
Solution Approach 1:
The patent applies preliminary actions by computing reference pressures before the actual fuel injection occurs. These reference pressures are calculated based on fuel supply conditions and stored for later comparison. By preparing the reference data in advance, the system can accurately distinguish actual injection signals from noise and overlapping waveforms during multi-stage injections.
Solution Approach 2:
The patent implements feedback mechanisms by continuously comparing detected fuel pressure variations against computed reference pressures. The system uses the difference between actual pressure readings and reference values to accurately determine injection start timing and compute maximum injection rates, even in the presence of noise and overlapping waveforms.
3Device complexity
If only the falling pressure waveform is used to compute maximum fuel injection rate, then the computation is simple, but the measurement precision deteriorates due to disturbance in the pressure waveform
Solution Approach 1:
The patent merges both the falling pressure waveform (during injection) and the rising pressure waveform (after injection) to compute the maximum fuel injection rate. By combining information from both waveforms and comparing them against reference pressures, the system achieves more accurate results while compensating for disturbances that may affect individual waveform segments.
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 computation of the maximum fuel injection rate, even in conditions with noise or overlapping pressure waveforms, enhancing the accuracy 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
An actual maximum fuel injection rate is computed based on a falling waveform 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 falling waveform and the rising waveform are modeled by modeling functions. A reference pressure is computed based on pressure during a specified time period before the falling waveform is generated. An intersection pressure is computed, at which the straight lines expressed by the modeling functions intersect to each other. The maximum fuel injection rate is computed based on a fuel pressure drop from the reference pressure to the intersection pressure.