Capacitive Level Sensor Insulating Casing
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Solution Overview
Problem
Existing level sensors for detecting liquids in containers face issues such as mechanical complexity, risk of jamming, freezing problems, and electromagnetic interference, particularly in capacitive sensors, which affect precision and reliability, especially in varying liquid states and conditions like freezing and heating.
Innovation Solution
A capacitive level sensor with a flexible design, using an array of electrodes isolated within an electrically insulating casing, connected to a microcontroller for precise capacitance measurement, capable of distinguishing liquid, air, and solid states, and adaptable to different lengths and tank configurations, with a structure that withstands temperature extremes and mechanical stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If electrodes are extended to increase measurement range, then level detection capability is improved, but electromagnetic interference increases
Solution Approach 1:
An insulating casing is introduced as an intermediary between the electrodes and the liquid medium. The casing allows the electrodes to extend into the liquid for measurement while preventing direct contact that would generate electromagnetic interference. The insulating material acts as a mediator that transmits the capacitive effect while blocking harmful electromagnetic signals.
Solution Approach 2:
The patent replaces direct electrical contact measurement with capacitive coupling through the insulating casing. Instead of electrodes directly touching the liquid (mechanical/electrical contact), the system uses electric field coupling through the insulator, substituting a mechanical contact system with a field-based measurement system that generates less interference.
2Measurement precision
If electrodes are directly in contact with liquid for measurement, then measurement precision is improved, but reliability deteriorates due to ageing and wear
Solution Approach 1:
The insulating casing serves as a protective intermediary between the electrodes and the liquid. It allows the electric field to penetrate for accurate capacitive measurement while physically protecting the electrodes from direct contact with the liquid, thereby preventing ageing, corrosion, and wear that would compromise reliability.
Solution Approach 2:
The insulating casing provides beforehand protection against the harmful effects of direct liquid contact. By pre-establishing this protective barrier, the system cushions the electrodes from exposure to corrosive, conductive, or abrasive liquid environments before any damage can occur.
3Device complexity
If sensor structure is simplified to reduce complexity, then ease of manufacture is improved, but adaptability to different conditions deteriorates
Solution Approach 1:
The insulating casing design provides multi-functionality: it serves as electrical insulation, mechanical protection, and a template for various electrode configurations. This universal structure can accommodate different electrode arrangements (single electrode, multiple electrodes, varying geometries) while maintaining the same basic protective function, enabling adaptability without increasing fundamental complexity.
Solution Approach 2:
The sensor is segmented into modular components: the insulating casing and the electrode array. This segmentation allows the electrode portion to be customized for different measurement requirements while the casing remains a standardized protective element, enabling adaptability through modular electrode configurations without redesigning the entire system.
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 sensor provides high precision, reliability, and flexibility in measuring liquid levels across different states and conditions, including freezing and heating, while minimizing electromagnetic interference and mechanical complexity, ensuring accurate and reliable operation.
Implementation Method 1
The circuit detects a variation of the capacitance between the facing electrodes that is proportional to the variation of the dielectric set between the electrodes
Implementation Method 2
proportional to the variation of the dielectric set between the electrodes, i.e., proportional to the level of the liquid set in between
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A sensor for detecting the level of a medium contained in a container, in particular a tank, comprises: an array of capacitive elements designed to be associated to the container (1), in particular so as to extend according to an axis of detection (X) of the level of the medium (L), the array of capacitive elements comprising a plurality of electrodes (J1-Jn), in particular on a face of an electrically insulating substrate (20) having a generally elongated shape, the electrodes (J1-Jn) being spaced apart from one another, in particular along the detection axis (X), and being preferably substantially coplanar with one another; at least one insulation layer (16) for insulating electrically the electrodes (J1-Jn) with respect to the inside of the container (1); and a controller (24) having a plurality of inputs. Each capacitive element comprises a set of electrodes connected together in common, in particular in parallel, each set of electrodes being connected to a respective input of the plurality of inputs. The controller (24) is pre-arranged for discriminating a value of capacitance associated to each electrode (J1-Jn) in order to deduce the level of the medium present container.