Magnetic Acceleration Sensor Cantilever Design
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Solution Overview
Problem
Conventional acceleration sensors face challenges in achieving high precision, reduced size, and low cost due to complex structures and obstructed displacement of spring elements, which complicates the detection of acceleration with multiple axes.
Innovation Solution
The acceleration sensor employs a pair of cantilevers with magnetic field generating and detecting devices, allowing for deflection and twisting to detect accelerations in multiple axes with a simple structure, using magnetoresistive elements and a bridge circuit to enhance sensitivity and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If distortion sensor elements are mounted on the supporting member to detect acceleration, then acceleration detection capability is achieved, but the structure becomes complicated by wirings and the size cannot be reduced
Solution Approach 1:
The patent replaces mechanical distortion sensor elements with a magnetic field-based detection system. Magnetic field generating devices are mounted on the supporting member, and magnetic field detecting devices detect the magnetic fields. This substitution eliminates the need for mechanical sensor mounting and complex wirings, thereby reducing structural complexity while maintaining acceleration detection capability through magnetic field changes caused by supporting member deformation
Solution Approach 2:
The magnetic field generating devices serve multiple functions: they generate magnetic fields for detection, act as mass elements that produce centrifugal force during rotation, and their positioning on the supporting member allows the supporting member to function as both a structural support and a sensor element. This multi-functionality reduces the overall number of components and simplifies the structure
2Measurement precision
If distortion sensor elements are mounted on the supporting member, then acceleration detection is enabled, but the size of the sensor cannot be reduced
Solution Approach 1:
The patent replaces bulky mechanical distortion sensor elements with compact magnetic field generating and detecting devices. The magnetic field generating devices can be小型ized as they are essentially magnets, and the detecting devices are electronic sensors that require minimal space. This substitution enables significant size reduction while maintaining the acceleration detection function through magnetic field measurements
Solution Approach 2:
The patent changes the detection parameter from mechanical distortion measurement to magnetic field detection. By measuring changes in magnetic field strength or direction caused by the movement of magnetic field generating devices attached to the supporting member, the system achieves acceleration detection with much smaller component sizes compared to traditional mechanical strain gauges or distortion sensors
3Device complexity
If distortion sensor elements are built in the spring part internally, then integration is improved, but displacement of the spring is obstructed so that high precision detection becomes difficult
Solution Approach 1:
The patent replaces internal mechanical sensor elements with magnetic field generating devices that are mounted on the supporting member rather than embedded within it. This external mounting approach allows the supporting member to deflect freely under acceleration forces without internal obstructions, while the magnetic field devices detect the movement through magnetic field changes, thereby maintaining both integration and high detection precision
Solution Approach 2:
The patent introduces magnetic fields as an intermediary between the supporting member's mechanical movement and the detection system. The magnetic field generating devices convert the mechanical displacement of the supporting member into magnetic field changes, which are then detected by magnetic field detecting devices. This intermediary approach allows non-contact detection, avoiding any physical obstruction to the spring's displacement while achieving precise acceleration measurement
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 design enables accurate detection of accelerations in three axes with a compact and cost-effective sensor, improving precision and reducing size by utilizing the deflection and twisting of cantilevers and magnetoresistive elements, while minimizing the need for dense magnetic field detection.
Implementation Method 1
a pair of magnetic field generating devices mounted respectively to each of the free ends for generating magnetic fields
Implementation Method 2
a pair of magnetic field detecting devices arranged to face each of the magnetic field generating devices, respectively, for detecting directions of the magnetic fields generated by each of the magnetic field generating devices
Data Source
AI summary
There is provided an acceleration sensor that is capable of detecting acceleration with high precision and capable of reducing the size and cost due to its simple structure. The acceleration sensor comprises: a pair of cantilevers arranged on a same straight line or almost in parallel in such a manner that positions of fixed ends and free ends are arranged to face in opposite directions from each other, and each of the free ends has a degree of freedom to deflect along a same direction; a pair of magnetic field generating devices mounted respectively to each of the free ends for generating magnetic fields; and a pair of magnetic field detecting devices arranged to face each of the magnetic field generating devices, respectively, for detecting directions of the magnetic fields generated by each of the magnetic field generating devices.