Capacitive Fluid Level Sensor With Shielded Double-Sided Electrodes
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Solution Overview
Problem
Conventional capacitive level sensors face challenges in accurately measuring fluid levels due to external electrical interference, temperature changes, and variations in the dielectric properties of fluids, leading to measurement errors and inaccuracies, especially in dynamic environments and the presence of deposits or oil sumps.
Innovation Solution
A capacitive fluid level sensor with a double-sided, decentered arrangement of electrodes on a printed circuit board, allowing for 100% measurement coverage without gaps and reducing errors from deposits and oil sumps, while using an electrically conductive housing to shield against external influences and dynamic motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional capacitive sensors are used, then the sensor structure is simple, but measurement precision deteriorates due to sensitivity to dielectric constant changes
Solution Approach 1:
The sensor electrode is divided into multiple segments arranged on both sides of the substrate, with each segment contributing to the measurement. This segmentation allows the sensor to measure fluid level across the entire path without dead zones while maintaining a manageable structure for each individual segment.
Solution Approach 2:
The electrode arrangement transitions from a single-sided linear configuration to a double-sided distributed configuration across the substrate. This dimensional change enables measurement coverage along the entire fluid path while eliminating dead zones that would exist in single-sided arrangements.
2Measurement precision
If single-sided electrode arrangement is used, then device complexity is low, but measurement precision deteriorates due to dead zones and gap coverage issues
Solution Approach 1:
Multiple electrode segments are distributed on both sides of the substrate, with gaps between segments on one side positioned to align with electrode coverage on the other side. This ensures continuous measurement coverage without dead zones while maintaining segmentational simplicity.
Solution Approach 2:
The measurement coverage of electrodes on the first side and electrodes on the second side are merged to provide complementary coverage. When one side has gaps, the other side provides coverage, eliminating dead zones and ensuring 100% measurement coverage along the fluid path.
3Reliability
If conventional capacitive sensing is used, then ease of manufacture is good, but reliability deteriorates due to external electrical interference and environmental influences
Solution Approach 1:
A conductive housing is introduced as an intermediary shielding structure between the external environment and the sensor electrodes. This housing blocks external electrical interference and environmental influences, protecting the measurement while adding a manageable layer of complexity.
4Measurement precision
If capacitive sensors are used in dynamic environments, then versatility is improved, but measurement precision deteriorates due to dynamic motion errors
Solution Approach 1:
Multiple electrode segments on both sides of the substrate provide distributed measurement points along the fluid path. This segmentation allows the system to identify and compensate for local disturbances caused by dynamic motion, maintaining precision in versatile applications.
Solution Approach 2:
Measurements from multiple electrode segments across both sides of the substrate are combined to provide redundant measurement data. This redundancy enables compensation for dynamic motion errors while maintaining adaptability to various operating conditions.
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 solution provides accurate and reliable fluid level measurements in various conditions, including dynamic environments, by eliminating dead zones and enhancing precision through redundant capacitance measurements and shielding, thus improving the robustness and reliability of the sensor.
Implementation Method 1
The sensor device is operable to determine the level of fluid material based on a capacitance between the at least one first electrode and the electrically conductive housing
Implementation Method 2
Capacitive level sensors detect the presence or lack of material in the vicinity of the plates by measuring the capacitance between the plates, which is proportional to the dielectric constant of the material filling the space between the plates
Implementation Method 3
An electrically conductive hollow housing surrounding the substrate, adapted to be capacitively coupled to the first electrode as a counter electrode
Data Source
Figure 1
Figure 2A~3
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AI summary
The present invention relates to a sensor device for determining a level of a fluid material along an axis of a container, the sensor device comprising a substrate having a first surface and a second surface, adapted to be placed in the container along the axis such that the first and second surfaces extend along the axis. At least one first electrode placed on the first surface of the substrate. An electrically conductive hollow housing surrounding the substrate, adapted to be capacitively coupled to the first electrode as a counter electrode of the at least one first electrode. The sensor device (100) is operable to determine the level of fluid material based on a capacitance between the at least one first electrode and the electrically conductive housing.