Optical Torque Sensor Using Encoder Wheels
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Solution Overview
Problem
Existing torque sensors, such as those in industrial screwdrivers and drill/driver tools, often rely on complex and expensive electronics or less repeatable slip clutches, which are not suitable for accurately applying a predetermined torque with a relatively inexpensive tool.
Innovation Solution
An optical torque sensor system that includes a torsionally resilient coupling member, an optical sensor system with encoder wheels and light guides, and a controller to detect torque by interpreting light transmission through encoder wheels, allowing for precise measurement and feedback of applied torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex electronics and clutches are used in driving tools, then torque control capability is improved, but tool cost increases
Solution Approach 1:
The patent replaces complex mechanical clutch systems with an optical sensor system that uses light transmission through encoder wheels to measure torque. The optical sensor detects the rotation of encoder wheels caused by torque application, providing precise measurements without requiring complex mechanical components.
Solution Approach 2:
The patent introduces an optical intermediary system consisting of light sources, encoder wheels with transparent and opaque sections, and optical sensors. This intermediary optical system mediates between the mechanical torque input and the electrical output signal, enabling precise torque measurement through light transmission variations.
2Reliability
If slip clutches are used in drill/drivers, then torque limitation is achieved, but measurement repeatability deteriorates
Solution Approach 1:
The patent implements a feedback system where the optical sensor continuously monitors the rotation of encoder wheels and provides real-time torque information to a controller. This feedback mechanism enables precise control and repeatable measurement of torque application, improving reliability compared to traditional slip clutches.
Solution Approach 2:
The patent substitutes the mechanical slip clutch with an optical measurement system that non-contactingly detects torque through light transmission. This substitution eliminates the mechanical wear and variability inherent in slip clutches, providing superior measurement repeatability and reliability.
3Measurement precision
If optical sensor system with encoder wheels is used, then torque measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the optical sensor system into distinct functional segments: light sources, encoder wheels with specific patterns, optical sensors, and a controller. This segmentation allows each component to be optimized independently and simplifies the overall system design while maintaining high measurement precision.
Solution Approach 2:
The encoder wheels serve multiple functions: they encode rotational position, detect torque magnitude, and provide reference signals for the optical sensor system. This multi-functionality reduces the need for separate components, thereby reducing overall device complexity while maintaining precision.
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
Enables accurate and repeatable torque measurement and feedback, allowing users to apply a predetermined torque with a cost-effective tool, improving the reliability and precision of torque application in various applications.
Implementation Method 1
an optical sensor system with encoder wheels and light guides, and a controller to detect torque by interpreting light transmission through encoder wheels
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A torque sensor that includes a sensor housing, a sensor input member at least partially received in the sensor housing, a sensor output member at least partially received in the sensor housing, a torsionally resilient coupling member that couples the sensor input member to the sensor output member and an optical sensor system that includes a light source, one or more encoders and one or more optical sensors. The encoder or encoders periodically transmit light between the light source and the at least one optical sensor based on an amount of relative rotation between the sensor input member and the sensor output member.