Rail Pressure Sensor Malfunction Detection via Differential Signal Analysis
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Solution Overview
Problem
Existing methods for detecting malfunctioning rail pressure sensors in common-rail injection systems are unreliable, particularly at high pressures, and can lead to safety risks and increased fuel consumption due to delayed detection and potential for mechanical overloading.
Innovation Solution
A method and apparatus that utilize a differential rail pressure signal generated from both analog and digital output signals from two rail pressure measurement devices, transmitted to a control unit for analysis, where it is compared against a threshold value to detect sensor malfunctions, enhancing detection reliability and preventing engine performance manipulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a redundant version of the rail pressure measurement is carried out by means of two rail pressure sensors, then the detection reliability is improved, but the device complexity and costs increase
Solution Approach 1:
The rail pressure sensor is divided into two independent measurement devices (first and second rail pressure measurement devices) that can be integrated into a single sensor unit. Each measurement device generates its own measurement signal, allowing independent evaluation and comparison of both signals to detect malfunctions reliably without requiring completely separate sensor systems
Solution Approach 2:
The patent combines two measurement devices within a single rail pressure sensor assembly, integrating their functions while maintaining independent signal generation capabilities. This merging approach enables redundant measurement and cross-checking within one sensor unit, reducing overall system complexity compared to using two completely separate sensors
2Speed
If analog transmission of rail pressure measurement signals is used, then the data rate requirement is met, but the possibility of manipulation lock is lost
Solution Approach 1:
The patent creates a digital copy of the analog measurement signal by converting the analog output signal from the rail pressure sensor into a digital form. This digital copy is then transmitted to the control unit and compared with the original analog signal, enabling both high data rate transmission and manipulation detection capabilities
3Reliability
If digital transmission of rail pressure measurement signals is used, then the manipulation lock is achieved, but the high data rates required by the injection system cannot be achieved
Solution Approach 1:
The patent generates a digital copy of the analog signal through A/D conversion and transmits this digital copy to the control unit. This enables manipulation lock capability while the analog signal path maintains the high data rate requirement for pressure control
4Loss of time
If pressure equalization with ambient pressure is performed when the common-rail injection system is unpressurized, then the detection can be performed before engine start, but no indication is provided of whether the pressure measurement value is correct at high system pressure
Solution Approach 1:
The patent enables continuous monitoring of both measurement signals throughout the entire operating range of the common-rail injection system. The control unit continuously compares the first and second measurement signals at all operating points, not just at ambient pressure, providing continuous detection capability from idle to high pressure operation
Solution Approach 2:
The control unit uses the comparison results of the two measurement signals to generate feedback information about sensor functionality. When deviations beyond a predetermined threshold are detected, the control unit identifies the malfunctioning sensor and can trigger appropriate countermeasures, providing continuous feedback about sensor health across all operating conditions
Data Source
AI summary
The present disclosure relates to internal combustion engines and the teachings thereof may be embodied in methods and apparatus for detecting a malfunctioning rail pressure sensor. Some embodiments may include a method for detecting a malfunctioning rail pressure sensor comprising: delivering an analog output signal characterizing the rail pressure to a control unit; generating a differential rail pressure signal as a digital output signal; delivering the differential rail pressure signal of the rail pressure sensor to the control unit; analyzing the analog output signal and the differential rail pressure signal in the control unit; and detecting a malfunctioning rail pressure sensor based on the analysis by the control unit.