Adaptive Fluid Level Detection Using Dual-Filter ECU Logic
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Solution Overview
Problem
Current fluid level sensors in internal combustion engines, especially in urea tanks, are prone to inaccuracies due to sloshing during transient vehicle movements, and struggle to detect refills reliably, leading to misleading level indications and potential engine performance limitations.
Innovation Solution
A control apparatus with an Electronic Control Unit connected to a fluid level sensor, using dual filtering techniques to generate a signal for fluid level increase detection, and implementing a learning procedure to determine stable fluid level changes, allowing for accurate refill detection and level updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If discrete level sensors are used to detect fluid level in tanks, then the device complexity and cost are reduced, but the measurement precision and reliability deteriorate due to sloshing during transient vehicle movements
Solution Approach 1:
The patent applies dynamics by implementing adaptive filtering with variable time constants that adjust based on vehicle operating conditions. The filtering parameters are dynamically modified according to vehicle speed, acceleration, and steering angle signals, allowing the system to adapt to transient movements and sloshing conditions while maintaining measurement precision with simple discrete sensors
Solution Approach 2:
The system uses feedback by continuously monitoring vehicle motion signals (speed, acceleration, steering angle) and using this information to adjust the filtering parameters. The ECU receives feedback from motion sensors and modifies the time constants of the filters accordingly, creating a closed-loop system that compensates for sloshing effects without requiring complex sensors
2Device complexity
If discrete level sensors with threshold values are used, then the device complexity is reduced, but the reliability deteriorates during transient driving states when fluid sloshing causes random threshold exceedances
Solution Approach 1:
The filtering parameters are dynamically adjusted based on real-time vehicle motion data. During transient driving states with high acceleration or steering inputs, the system increases the time constant to filter out noise from fluid sloshing, while during steady-state conditions it reduces the time constant for faster response, thereby maintaining reliable level indications across all operating conditions
Solution Approach 2:
The patent changes the parameter (time constant) of the filtering system based on vehicle operating conditions. By modifying the filtering characteristics according to motion signals, the system maintains reliable level detection during both transient and steady-state operations without requiring additional sensors or complex hardware
3Measurement precision
If continuous fluid level sensors are used to achieve precise level measurement, then the measurement precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent introduces an intermediary (the adaptive filtering algorithm) between the simple discrete level sensor and the control system. This intermediary processes the sensor signals and vehicle motion data to compensate for the limitations of discrete sensors, achieving continuous-like measurement precision without requiring continuous sensors, thereby reducing device complexity and cost while maintaining high measurement precision
4Device complexity
If simple filtering is applied to level signals, then the device complexity is reduced, but the ability to detect refills accurately during vehicle movement deteriorates
Solution Approach 1:
The filtering system is made dynamic by adjusting the time constant based on vehicle motion signals. During refill operations, even during vehicle movement, the system adapts the filtering parameters to distinguish between sloshing caused by vehicle motion and actual fluid level changes, enabling reliable refill detection with moderate processing complexity
Data Source
AI summary
A control apparatus for detecting a variation of a fluid level in a tank is disclosed. The control apparatus includes an Electronic Control Unit connected to the fluid level sensor. The ECU is configured to monitor a signal value representative of a fluid level in the tank; filter the fluid level signal value using a first filter to obtain a first filtered signal and using a second filter to obtain a second filtered signal, the first filter having a time constant (τ1) lower than a time constant (τ2) of the second filter; calculate an integral value of a difference between the first filtered signal and the second filtered signal; and generate a signal representative of the detection of an increase in the fluid level in the tank when the integral value is greater than a predefined threshold.