Fuel Injection Quantity Estimation from Rail Pressure Profiles
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Solution Overview
Problem
Conventional injection systems for internal combustion engines struggle to accurately determine the fluid injection quantity per cylinder per working cycle, as they do not account for injector-specific throughflow deviations due to manufacturing tolerances or coking over the service life of the injector.
Innovation Solution
A method and device that utilize a pressure sensor to detect measurement signals in the high-pressure region of the injection system, segmenting pressure profiles before and after fluid injection, and performing kernel density estimation to determine probability density functions, thereby accurately ascertaining the pressure difference and fluid injection quantity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional injection systems determine injection quantity based on electrical actuation duration and compensate hydraulic opening duration, then the system can operate with simple measurement methods, but the measurement precision deteriorates because injector-specific throughflow deviations due to manufacturing tolerances or coking are not accounted for
Solution Approach 1:
The patent replaces electrical measurement methods with acoustic measurement methods. Instead of using electrical actuators and sensors to measure injection quantity, the system uses acoustic sensors to detect pressure waves generated during fuel injection. The acoustic signal characteristics (amplitude, frequency, duration) are analyzed to determine the actual injection quantity, thereby achieving precise measurement without complex electrical measurement systems.
Solution Approach 2:
The patent introduces acoustic waves as an intermediary to measure injection quantity. The fuel injection process generates acoustic pressure waves in the fuel rail, and these waves serve as carriers of information about the injection event. By analyzing the acoustic signals, the system can infer injection quantity without directly measuring fuel flow or pressure changes, thus avoiding the need for complex direct measurement systems.
2Reliability
If conventional systems use global air-to-fuel ratio control, then the control system remains simple, but the reliability deteriorates because individual cylinder injection variations and uniform air distribution are not ensured
Solution Approach 1:
The patent segments the measurement process into distinct phases: pre-injection acoustic baseline measurement, injection event detection, and post-injection analysis. By dividing the measurement into these segments, the system can accurately identify injection start and end times, calculate injection duration, and determine injection quantity for each cylinder independently, thereby ensuring reliable combustion control.
Solution Approach 2:
The patent implements feedback by continuously monitoring acoustic signals from each cylinder's injection event and using this information to adjust subsequent injections. The system analyzes the acoustic characteristics of each injection event and feeds this information back to the control unit, which can then compensate for variations in injector performance and maintain optimal air-to-fuel ratios for reliable combustion.
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 determination of the fluid injection quantity, improving engine operation and compliance with emissions standards by accounting for injector-specific throughflow variations.
Implementation Method 1
detecting a measurement signal using the pressure sensor during the operation of the injection system. The measurement signal characterizing the fluid pressure in the high-pressure region
Data Source
AI summary
A method and a device for ascertaining a fluid injection quantity of an injection system. The injection system includes a high-pressure pump, a high-pressure region that adjoins the high-pressure pump, a pressure sensor, and an injector that is fed from the high-pressure region. The method includes detecting a measurement signal using the pressure sensor and segmenting a first pressure profile from the measurement signal. The first pressure profile characterizes the pressure profile prior to a fluid injection using the injector. The method also includes segmenting a second pressure profile from the measurement signal. The second pressure profile characterizes the pressure profile after the fluid injection using the injector. The method also includes performing a kernel density estimation using the first pressure profile and the second pressure profile, ascertaining a pressure difference, and ascertaining the fluid injection quantity using the pressure difference.