Ultrasonic Fill Level Sensor Cleaning Reference Surface
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Solution Overview
Problem
Ultrasonic fill-level sensors in tanks with urea/water solutions face inaccuracies due to impurities and gas collections on reference surfaces, which cause uncontrolled signal reflection and scattering, leading to unreliable propagation time measurements.
Innovation Solution
A method involving the use of an ultrasonic pulse to clean reference surfaces, with adjustable parameters such as frequency, duration, and amplitude, to remove impurities like gas bubbles and solid deposits, followed by a second propagation time measurement to calculate the fill level accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If ultrasonic propagation time measurement is used to determine fill level, then non-contact measurement capability is improved, but measurement precision deteriorates due to signal reflection and scattering by impurities on reference surfaces
Solution Approach 1:
The system performs a reference measurement before the actual fill level measurement to establish the propagation speed of ultrasonic signals in the liquid additive. This preliminary action accounts for variations in liquid composition and ensures accurate distance calculation from the measured propagation time, resolving the precision issue while maintaining non-contact measurement capability
Solution Approach 2:
The ultrasonic sensor system automatically performs reference measurements and uses the determined propagation speed to correct subsequent fill level measurements. The system self-calibrates by utilizing the known path length to reference surfaces and the measured propagation time, eliminating the need for manual calibration and maintaining measurement precision despite impurities on reference surfaces
2Measurement precision
If reference surfaces are used for ultrasonic propagation time measurement, then propagation speed determination is improved, but reliability deteriorates due to impurities and gas collections causing uncontrolled signal reflection
Solution Approach 1:
The system separates the reference measurement function from the fill level measurement function. Reference surfaces are specifically designed for propagation speed determination only, while fill level measurements use the liquid surface as the reflection point. This extraction of functions prevents impurities on reference surfaces from affecting fill level measurement reliability
Solution Approach 2:
The system introduces an intermediate calculation step where propagation speed is first determined through reference measurements, then used as a mediator to convert fill level propagation times into accurate distance measurements. This intermediary approach isolates the fill level measurement from direct contact with impure reference surfaces, maintaining both precision and reliability
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 method ensures precise fill-level measurements by effectively cleaning reference surfaces, allowing for reliable ultrasonic signal propagation and reducing the need for frequent cleaning, thus enhancing measurement accuracy and energy efficiency.
Implementation Method 1
The propagation speed of the ultrasonic waves in a tank regularly depends on the composition of the liquid additive
Implementation Method 2
The ultrasonic signal emitted by the ultrasonic emitter is reflected at the liquid level
Implementation Method 3
cleaning at least one reference surface in the liquid additive with the aid of at least one ultrasonic pulse
Data Source
AI summary
A method for measuring the fill level of a liquid additive in a tank using an ultrasonic sensor includes initially carrying out a measurement of a first propagation time of an ultrasonic signal from the ultrasonic sensor to a liquid level of the liquid additive. This is followed by cleaning of at least one reference surface in the liquid additive with the aid of at least one ultrasonic pulse. Then at least one second propagation time of an ultrasonic signal from the ultrasonic sensor to the at least one reference surface is measured and the fill level is calculated from the first propagation time and the second propagation time. A delivery unit having at least one ultrasonic sensor for installation in a liquid additive tank is also provided.