Torque Sensor Using Gastight Chamber Volume Deformation

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Solution Overview

Problem

Existing torque sensors face limitations in resolution and accuracy due to low signal-to-noise ratio, sensitivity to environmental factors, nonlinearity, and hysteresis, particularly in strain gauge and magneto-elastic methods.

Innovation Solution

A torque sensor design featuring a gastight chamber that changes volume in response to torque, utilizing a pressure sensor to measure pressure changes within the chamber, which are then converted to torque values, providing higher resolution and accuracy through direct dimensional change detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If strain gauge method is used to measure shaft deformation, then torque measurement capability is achieved, but measurement precision deteriorates due to low signal-to-noise ratio and high sensitivity to environmental factors

Engineering Contradiction:

Improvetorque measurement precisionVSAvoidsensitivity to environmental factors

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the mechanical strain gauge measurement system with a capacitive sensing system. Instead of using strain gauges that measure resistance change due to mechanical deformation, the invention uses capacitive sensors that detect changes in capacitance caused by torque-induced deformation of the shaft. This substitution eliminates the need for adhesive bonding and reduces sensitivity to environmental factors such as temperature and humidity, thereby improving measurement precision and reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the measurement parameter from electrical resistance (in strain gauges) to capacitance. By measuring capacitance changes rather than resistance changes, the system achieves higher signal-to-noise ratio and reduced sensitivity to environmental factors. The capacitive sensors detect subtle changes in the electric field caused by shaft deformation, providing more precise and reliable torque measurements.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If magneto-elastic effect is used for torque sensing, then torque measurement is achieved, but measurement precision deteriorates due to nonlinearity and hysteresis

Engineering Contradiction:

Improvetorque measurement precisionVSAvoidnonlinearity and hysteresis characteristics

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the magneto-elastic sensing system with a capacitive sensing system. Instead of relying on changes in magnetic properties of ferromagnetic materials under torque, the invention uses capacitive sensors that directly measure mechanical deformation through capacitance changes. This eliminates the nonlinearity and hysteresis inherent in magneto-elastic materials, providing more linear and accurate torque measurements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If indirect detection via strain gauge is used, then torque measurement is achieved, but measurement precision deteriorates due to ineffective force transmission through adhesive

Engineering Contradiction:

Improvetorque measurement precisionVSAvoidadhesive bonding process sensitivity

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the adhesive-bonded strain gauge system with directly mounted capacitive sensors. The capacitive sensors are positioned to detect changes in the electric field caused by shaft deformation without requiring adhesive bonding. This direct mounting approach eliminates the intermediate adhesive layer, ensuring effective force transmission and improving measurement precision while simplifying the manufacturing process.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enhanced accuracy and resolution by leveraging high-resolution pressure sensors and deformation-enhancing structures, minimizing sensitivity to environmental factors and allowing for precise torque measurement.

Implementation Method 1

the gastight chamber is arranged to change its volume by deformation of the body when the body is subjected to a torque, wherein the volume change causes a change of pressure of the enclosed gas in the gastight chamber

Methodology Applied

Scientific EffectVolume change of gas: Boyle's Law

Data Source

PatentUS10309847B2Torque sensor

Publication Date: 2019.06.04 CHENG PENG

AI summary

The torque sensor has a body. A first gastight chamber is defined at least partly by the body. A pressure sensor is connected with the gastight chamber for measuring the pressure in the gastight chamber. A pressure to torque converter is connected to the pressure sensor. The gastight chamber is arranged to change its volume by deformation of the body when the body is subjected to a torque wherein the volume change causes a change of pressure of the enclosed gas in the gastight chamber.