Wireless Liquid Presence Sensor for Sealed Containers
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Solution Overview
Problem
Existing liquid presence sensors for containers face challenges such as the risk of leakage due to electrode penetration, high costs, and the need for periodic maintenance, especially in airtight and low-cost applications like the automotive field, where electrolysis and battery replacement are concerns.
Innovation Solution
A magnetic transmission wireless link without a continuous magnetic circuit and an external power supply, using a variable impedance element formed by electrical conductors with a capacitor, which detects liquid presence by analyzing the damping of damped sinusoidal waves, eliminating the need for electrode penetration and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrodes are passed through the container wall to detect liquid presence, then liquid level detection is enabled, but the risk of leakage increases
Solution Approach 1:
The patent replaces mechanical/electrical contact-based liquid level detection (electrodes penetrating the container wall) with a magnetic field-based detection system. The sensor uses magnetic coupling through the container wall to detect liquid presence without physical penetration, thereby maintaining container seal integrity while enabling accurate liquid level measurement.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary medium to transfer information about liquid presence from inside the container to the external sensor. The magnetic field couples the internal liquid level information with the external detection circuitry without requiring physical penetration of the container wall, thus preserving seal integrity.
2Reliability
If complex sensor components (ultrasound transducer, radio wave transmitter/receiver) are used for wireless liquid level detection, then leakage risk is eliminated, but production cost increases
Solution Approach 1:
The patent changes the operational parameters of the magnetic sensor system to use low-frequency magnetic fields and simple coil structures instead of complex ultrasound or radio wave systems. This parameter change enables wireless liquid level detection with minimal hardware complexity, significantly reducing production costs while maintaining container seal integrity.
Solution Approach 2:
The patent employs simple, inexpensive magnetic coils and basic electronic components for the sensor system, replacing expensive ultrasound transducers and radio wave communication modules. This approach uses cost-effective elements that achieve the detection function without requiring complex or expensive hardware.
3Reliability
If battery-powered sensor elements are placed inside the container for wireless detection, then leakage risk is eliminated, but periodic maintenance is required
Solution Approach 1:
The patent extracts the power source and complex electronics from inside the container, placing only simple passive magnetic coils within the container and locating the active sensor electronics externally. This extraction eliminates the need for internal batteries and power management circuits, thereby eliminating periodic maintenance requirements while preserving container seal integrity.
Solution Approach 2:
The sensor system is designed to be self-powered through magnetic coupling, where the external sensor provides both the magnetic field for detection and the power transfer to internal components without requiring internal batteries. This self-service approach eliminates maintenance needs by removing consumable power sources from the sealed container environment.
Data Source
Figure 1~2
Figure 3~4
AI summary
The sensor (1) has a sensor element (1a) placed at exterior of a sealed container (2). Another sensor element (1c) has an electrical circuit (1d) with a variable impedance element sensible to liquid (200) in the container. The impedance of the impedance element varies according to liquid presence/absence. The impedance variation modifies oscillation properties of a passive secondary oscillating circuit. A wireless link (3) provides wireless connection between the sensor elements by assuring magnetic coupling between primary and secondary coils (4, 9) of respective electrical circuits (1b, 1d).