Offset Capacitive Probe for Liquid Level Measurement
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Solution Overview
Problem
Existing liquid level measurement devices in vehicle tanks, particularly fuel and AdBlue tanks, face challenges due to the varying dielectric constant of liquids and sensitivity/resolution issues related to electrode geometry and spacing, leading to inaccurate measurements.
Innovation Solution
A capacitive probe design with offset capacitive elements arranged in multiple rows along a longitudinal axis, creating additional measurement zones and improving resolution, combined with a processing unit that converts capacitance values into binary codes using switching thresholds to generate accurate liquid level information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a segmented capacitive probe with interdigitated electrodes is used, then the device can measure liquid level, but the dielectric constant of the liquid affects the measurement accuracy
Solution Approach 1:
The capacitive probe is divided into multiple capacitive elements arranged in rows, where each element contributes to the overall capacitance measurement. This segmentation allows the system to process capacitance values from multiple elements to determine liquid level while compensating for dielectric constant variations through aggregated measurement data.
Solution Approach 2:
The patent transitions from a single-row capacitive arrangement to a multi-row configuration with offset elements along the longitudinal axis. This dimensional expansion creates additional measurement zones and allows the system to overcome the limitation of dielectric constant sensitivity by distributing measurement points across multiple spatial dimensions.
2Measurement precision
If the capacitive elements are arranged in a conventional configuration, then the device structure is simple, but the sensitivity and resolution of the sensor are limited
Solution Approach 1:
The patent introduces a multi-row arrangement with offset elements along the longitudinal axis, transforming a single-dimensional linear arrangement into a two-dimensional grid structure. This dimensional change creates additional measurement zones between elements, thereby improving resolution without significantly increasing overall device complexity.
Solution Approach 2:
The system dynamically processes capacitance values from multiple offset elements to determine liquid level. The evaluation unit analyzes the combined signal from multiple capacitive elements, allowing the measurement resolution to be improved through computational processing rather than solely through physical refinement of individual elements.
3Measurement precision
If multiple rows of capacitive elements with offset arrangement are used, then the measurement resolution is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple capacitive elements into a unified measurement system where the evaluation unit processes signals from all elements collectively. By merging the functionality of multiple offset elements into a single level measurement process, the system achieves improved resolution while managing complexity through integrated evaluation rather than separate processing for each element.
Solution Approach 2:
The multi-row capacitive element arrangement serves multiple functions simultaneously: each element contributes to overall level measurement, the offset arrangement creates additional measurement zones for improved resolution, and the distributed configuration provides redundancy against dielectric constant variations. This multi-functionality justifies the increased number of elements by delivering multiple benefits from a single structural modification.
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
The solution reduces the impact of dielectric constant variations and enhances sensitivity and resolution, providing more precise liquid level measurements with improved noise immunity and protection against mechanical and electromagnetic interference.
Implementation Method 1
each capacitive element being capable of generating a capacitance value as a function of the liquid level on the capacitive element
Data Source
Figure 1~2
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AI summary
There is proposed a device for measuring the level of a liquid in a vehicle tank comprising at least one capacitive probe, the capacitive probe comprising a support structure supporting at least one plurality of capacitive elements arranged in such a way as to form at least two rows of capacitive elements (C1, C2) extending along a longitudinal axis, the rows of capacitive elements being spaced apart along an axis which is transverse to the longitudinal axis. The capacitive elements (11, 12) of the two rows of capacitive elements are offset along the longitudinal axis with respect to one another from one row to the next.