Magnetoresistive Sensor Liquid Level Detection
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Solution Overview
Problem
Existing liquid level sensors for tanks face issues with size, cost, and reliability due to complex mechanical designs and large diameter guide tubes, which can lead to mechanical failures and inefficiencies in detecting liquid levels.
Innovation Solution
A compact liquid level sensor system utilizing a straight rod magnetic arm with a magnetoresistive angle sensor chip, which provides a simpler and more reliable method for detecting the rotation of a permanent magnet, allowing for precise liquid level measurement through a linearly proportional rotation angle to liquid surface height, with a wireless communication module for remote monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bent arm mechanism with permanent magnet is used to detect liquid level, then the liquid level can be measured remotely without electrical components in the tank, but the device size and mechanical complexity increase
Solution Approach 1:
The patent replaces the mechanical bent arm mechanism with a magnetic field-based detection system. A permanent magnet is attached to a floating element that moves with liquid level changes, and its position is detected by magnetic sensors (such as Hall effect sensors or magnetoresistive sensors) mounted on the tank exterior. This substitution eliminates complex mechanical linkages while maintaining remote measurement capability and improving reliability.
Solution Approach 2:
The floating element serves multiple functions: it responds to liquid level changes, carries the permanent magnet for position detection, and provides mechanical stability. This multi-functionality reduces the need for separate components, thereby simplifying the overall device structure while maintaining measurement accuracy.
2Reliability
If a large diameter guide tube is used to ensure proper float operation, then the float can move smoothly, but the device size increases and mechanical failure risk increases
Solution Approach 1:
The patent eliminates the need for a large diameter guide tube by replacing mechanical float movement detection with magnetic field detection. The floating element can be smaller and simpler since it only needs to move vertically with liquid level changes, and its position is tracked magnetically rather than through complex mechanical linkages. This reduces both the guide tube size and the risk of mechanical failure.
Solution Approach 2:
The patent changes the detection parameter from mechanical position tracking to magnetic field measurement. This allows the use of smaller, more compact components while maintaining detection accuracy, thereby reducing the overall device size and volume without compromising reliability.
3Measurement precision
If multiple magnetic sensors are arranged in a circular array to detect permanent magnet position, then the liquid level can be measured with good resolution, but the device complexity and cost increase
Solution Approach 1:
The patent replaces the circular array of magnetic sensors with a single magnetic sensor or a simplified sensor configuration. By using a permanent magnet with specific magnetic pole arrangements (such as alternating North-South poles) on the floating element, the position can be determined with high resolution using fewer sensors, thereby reducing device complexity and cost while maintaining measurement precision.
Solution Approach 2:
The patent changes the magnetic field configuration to enable position detection with reduced sensor count. By optimizing the permanent magnet's magnetic pole arrangement and the sensor's detection algorithm, high-resolution liquid level measurement can be achieved with a single sensor or minimal sensor array, simplifying the overall system.
4Measurement precision
If a complex mechanical linkage is used to convert float movement to rotational motion, then the liquid level can be measured, but the device complexity and potential failure points increase
Solution Approach 1:
The patent directly couples the permanent magnet to the floating element, eliminating complex mechanical linkages. The floating element's vertical movement is directly translated to the permanent magnet's position change, which is detected by magnetic sensors. This direct coupling maintains measurement accuracy while significantly reducing mechanical failure risk by eliminating intermediate linkages.
Solution Approach 2:
The patent extracts and eliminates the complex mechanical linkage components from the system, retaining only the essential floating element and permanent magnet combination. This simplification removes potential failure points while preserving the core measurement function through magnetic field detection.
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 size and cost of the sensor system while improving performance, offering higher resolution and reliability, and enabling efficient remote monitoring of liquid levels in tanks.
Implementation Method 1
a magnetoresistive angle sensor chip attached to the PCB on the side towards the permanent magnet, and the magnetoresistive angle sensor chip is electrically interconnected with a control circuit; the magnetoresistive angle sensor chip is configured to output an analog voltage signal to the control circuit in correspondence with the angle of rotation of the permanent magnet
Implementation Method 2
a float inside the guide tube floating on the surface of the liquid, that moves up and down as the liquid level varies in the guide tube
Implementation Method 3
a rotating shaft, said rotating shaft mechanically and coaxially coupled with the float, while the float is in the process of moving up and down, the rotating shaft rotates around a fixed axis of rotation
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A liquid level sensor system for remotely monitoring the liquid level in a tank, the system comprising a first fixed portion (1) with a first liquid level response unit, and a second fixed portion (2) with a second liquid level response unit; a guide tube (14) inserted into the tank and attached to the bottom of the first fixed portion (1); the guide tube (14) is provided with a multitude of ports (27), such that the liquid level in the guide tube (14) is flush with the liquid level in the tank; the first liquid level response unit comprises a float (15) floating up and down with the variation of the liquid level in the guide tube (14), a rotating shaft (19) rotating around a relatively fixed axis of rotation (16) in the up and down floating process of the float (15), and a permanent magnet (139); the second fixed portion (2) is attached to the top of the first fixed portion (1); the second liquid level response unit comprises a PCB (104), a magnetoresistive angle sensor chip (103), and a control circuit electrically connected to the magnetoresistive angle sensor chip (103); the magnetoresistive angle sensor chip (103) outputs an analog voltage signal to the control circuit according to the rotation angle of the permanent magnet (139), and the control circuit calculates the height of the liquid level according to the analog voltage signal.