High-Speed Rheometer Optical Torque Measurement
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Solution Overview
Problem
Traditional rheometers have limited measuring accuracy and range, particularly at high shearing rates, and struggle to test the effects of different surfaces on fluid movement, with existing devices either lacking sensitivity at high rates or being inaccurate at lower rates.
Innovation Solution
A high-speed rheometer with an optical torque measuring assembly that includes a torsion bar and a prism, using light reflection to measure torsion angles and convert them into torque values, allowing for precise measurement across a wide range of shearing rates from 1/s to 1×10^6/s.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional stress-strain sensors or torque motors are used for measurement, then the device structure is simple, but the measuring accuracy is limited and the measuring range is narrow (only two or three orders of magnitude)
Solution Approach 1:
The patent replaces traditional mechanical stress-strain sensors or torque motors with an optical torque measuring assembly. This assembly uses a prism, light source, and four-quadrant detector to measure torsion angles optically, converting mechanical measurement into an optical measurement system. This substitution eliminates mechanical contact and friction, achieving higher measurement accuracy while enabling a measuring range spanning four or more orders of magnitude.
Solution Approach 2:
The patent introduces a torsion bar as an intermediary element between the rotating system and the measurement system. The torsion bar converts rotational torque into torsional deformation, which is then measured by the optical system through prism deflection. This intermediary enables precise measurement of torque across a wide range by translating mechanical quantities into measurable optical signals.
2Measurement precision
If conventional motor-based gap control is used, then the control mechanism is simple, but the noise is large and the control accuracy is low with difficulty in obtaining smaller gaps
Solution Approach 1:
The patent replaces conventional motor-based gap control with an optical interference measurement system. The system uses a laser source, beam splitter, reference mirror, and detector to measure gap dimensions through optical interference patterns. This substitution eliminates mechanical contact and motor noise, achieving nanometer-level control accuracy and enabling precise control of smaller gaps without the limitations of motor resolution and noise.
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 high-speed rheometer achieves enhanced measuring accuracy and a broader range, capable of measuring both low and high shearing rates with improved sensitivity and resolution, suitable for various fluid types.
Implementation Method 1
The optical torque measuring assembly includes a prism coaxially disposed on the torsion bar; a light source configured to emit light toward a side surface of the prism to form first reflected light; and a four-quadrant detector configured to receive the first reflected light
Data Source
AI summary
A high-speed rheometer includes a base, a driving device disposed on the base, a lower sample assembly connected with the driving device, an upper sample assembly disposed above the lower sample assembly, a torsion bar disposed on the upper sample assembly and being torsional upon the rotation of the upper sample assembly, and an optical torque measuring assembly. The lower sample assembly is rotatable under the driving of the driving device, and the upper sample assembly is rotatable under the driving of the fluid. The optical torque measuring assembly is used to measure a torsion angle of the torsion bar so as to obtain a torque generated during shearing the fluid to be tested.