Single Crystal Semiconductor Torque Sensor Fatigue Resistance
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Solution Overview
Problem
Conventional wire strain gauges used for measuring dynamic quantities of rotating bodies, such as torques, face issues with cyclic fatigue, reliability, corrosion, and complexity, making them unsuitable for high-reliability applications like automotive drive axels and corrosive environments.
Innovation Solution
A rotating body dynamic quantity measuring device utilizing a semiconductive single crystal impurity-diffused layer on a rotating body, which provides high reliability due to its resistance to cyclic loads and corrosion, and is lightweight and compact, allowing for precise torque measurements without the need for complex balancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wire strain gauge is used to measure dynamic quantities of a rotating body, then measurement capability is provided, but cyclic fatigue occurs and reliability degrades over time
Solution Approach 1:
The patent changes the material parameter from metal thin film (wire strain gauge) to semiconductive single crystal. This material substitution fundamentally alters the fatigue characteristics, enabling the sensor to withstand high cyclic deformations without the cyclic fatigue that plagues metal thin film sensors. The single crystal structure provides superior fatigue resistance while maintaining measurement capability.
Solution Approach 2:
The patent employs a composite structure combining semiconductive single crystal with specific mounting arrangements. The single crystal substrate is mounted on the rotating body through a mounting portion that distributes mechanical stresses, creating a composite system that leverages the fatigue resistance of the single crystal while the mounting structure prevents stress concentration that could lead to failure.
2Reliability
If wire strain gauges are used in corrosive environments, then measurement is possible, but corrosion occurs and reliability decreases
Solution Approach 1:
The patent changes the material composition from metal thin film to semiconductive single crystal. This parameter change fundamentally improves corrosion resistance, as the single crystal structure lacks the grain boundaries and surface defects that make metal thin films susceptible to corrosion. The semiconductive material inherently resists corrosion while maintaining electrical properties for measurement.
3Measurement precision
If complex wiring and circuits are added to transmit detected values, then measurement capability is enhanced, but device complexity and weight increase
Solution Approach 1:
The patent extracts the measurement and processing functions into an integrated compact unit that can be mounted directly on the rotating body. By taking out the essential measurement capability and packaging it in a self-contained module with internal signal processing, the patent eliminates the need for complex external wiring while maintaining measurement precision. The extracted measurement function is encapsulated in a form factor that minimizes added complexity.
4Reliability
If heavy mounting structures are used to secure the device, then attachment reliability is improved, but centrifugal force increases and balancing becomes problematic
Solution Approach 1:
The patent changes the material density parameter by using semiconductive single crystal, which has lower density than traditional metal mounting structures. This parameter change reduces the device weight, thereby minimizing the centrifugal force acting on the mounted device. The reduced weight eliminates the need for heavy mounting structures while maintaining attachment reliability through optimized lightweight mounting interfaces.
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 ensures long-term reliability and precision in measuring dynamic quantities with reduced susceptibility to fatigue and corrosion, and eliminates the need for complex balancing and heavy infrastructure, enhancing the device's reliability and usability in demanding environments.
Implementation Method 1
a semiconductive single crystal impurity-diffused layer is placed on a rotating body
Data Source
AI summary
A single crystal semiconductor including a Wheatstone bridge circuit formed of an impurity diffusion layer whose longitudinal direction is aligned with a particular crystal orientation is connected to a rotating body. A rotating body dynamic quantity measuring device and a system using the measuring device are fatigue- and corrosion-resistant because of the single crystal semiconductor used and are not easily affected by temperature variations because of the bridge circuit considering a single crystal anisotropy.