Film Strain Gauge Torque Sensor for Compact High-Resolution Sensing
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Solution Overview
Problem
Conventional torque sensors face challenges in miniaturization and design flexibility due to their large size, thickness, and limited resolution, particularly in rotary torque sensors with strain gauges and capacitive sensors.
Innovation Solution
A torque sensor design featuring a first and second plate-like member with a spacer, film-shaped strain gauges and wires in a recessed outer circumferential region, allowing for miniaturization and high resolution through a compact configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional rotary torque sensor with strain gauges is used, then torque measurement function is achieved, but the sensor size becomes large
Solution Approach 1:
The patent uses film-shaped strain gauges instead of conventional bulky strain gauge installations. The film-shaped configuration allows the strain sensing element to be extremely thin and flexible, enabling miniaturization of the torque sensor while maintaining the ability to detect torque through strain measurement in the film structure.
Solution Approach 2:
The patent transitions from conventional three-dimensional strain gauge installations to a two-dimensional film-shaped configuration. By placing the strain gauge as a thin film on the plate-like member, the sensor achieves reduced volume while maintaining measurement capability through the film's planar strain detection.
2Length of stationary object
If wiring and strain gauges are installed in conventional torque sensors, then torque detection is enabled, but the thickness increases
Solution Approach 1:
The film-shaped strain gauge and film-shaped wire are integrated into an extremely thin configuration that can be installed within the limited thickness space between the first and second plate-like members. This film technology eliminates the need for bulky conventional wiring and strain gauge installations, achieving thinness of not more than 1 mm.
Solution Approach 2:
The patent integrates the strain gauge, wiring, and protective structure into a unified film-shaped assembly. The film-shaped wire is directly connected to the film-shaped strain gauge, and both are protected by the recess structure, creating a compact integrated unit that reduces overall device complexity and thickness.
3Length of stationary object
If capacitive torque sensor design is used, then measurement function is achieved, but minimum thickness is constrained
Solution Approach 1:
The patent employs film-shaped strain gauges that can function effectively at extremely thin dimensions. The film structure maintains sufficient mechanical properties and strain detection capability even when the total sensor thickness is reduced to not more than 1 mm, overcoming the minimum thickness constraints of conventional capacitive designs.
Solution Approach 2:
The patent replaces capacitive measurement principles with strain gauge-based mechanical strain detection. This substitution allows for more flexible thickness design, as the strain gauge method does not require maintaining a specific gap distance between substrates like capacitive sensors do, enabling thinner overall construction.
4Measurement precision
If conventional strain gauge and material combinations are used, then torque sensing is achieved, but resolution design freedom is limited
Solution Approach 1:
The patent enables resolution adjustment by changing the physical dimensions of the film-shaped strain gauge, particularly its length. By making the strain gauge length a variable parameter, the resolution can be tuned across a wide range without being constrained by fixed material properties, achieving resolution design freedom of not less than one order of magnitude.
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 design achieves a compact, high-resolution torque sensor with improved sensitivity and reliability, enabling precise torque detection and versatility for various applications.
Implementation Method 1
at least one film-shaped strain gauge disposed in the recess and a film-shaped wire connected to the at least one film-shaped strain gauge are provided
Data Source
AI summary
A torque sensor is provided that achieves miniaturization and that has a high degree of freedom in design of resolution. The torque sensor includes: a first plate-like member including a spacer that is plate-like; and a second plate-like member fastened to the first plate-like member. In an outer circumferential region of the second plate-like member outside the spacer, a film-shaped strain gauge disposed in a recess that is provided on an outer edge of the spacer, and a film-shaped wire connected to the film-shaped strain gauge are provided.