Torque Transducer Assembly for Precision Screwdriver Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rotary power tools, such as screwdrivers, lack the capability to deliver precise applications of torque during fastener-driving operations, as mechanical clutches are not effective for precise torque control.
Innovation Solution
A transducer assembly is integrated into the power tool, comprising an inner hub, an outer rim, flexible webs, and sensors to detect strain, allowing for accurate measurement and control of reaction torque applied to the workpiece, with a master controller adjusting motor speed to achieve predefined torque values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mechanical clutch is used to limit torque, then the torque output can be increased or decreased, but precise torque control during fastener-driving operations cannot be achieved
Solution Approach 1:
The patent replaces the purely mechanical clutch system with an electromechanical system that incorporates strain sensors (electrical components) to detect torque. The strain sensors mounted on flexible webs provide electrical signals proportional to applied torque, enabling precise measurement and electronic control to supplement the mechanical torque limiting function.
Solution Approach 2:
The patent implements feedback by using strain sensors to continuously monitor the torque applied to the fastener and providing this information to a controller. The controller can then adjust motor operation based on the measured torque, ensuring precise torque control and preventing over-torquing, which resolves the limitation of open-loop mechanical clutch systems.
2Measurement precision
If strain sensors are mounted on flexible webs, then torque can be accurately detected, but the device complexity increases
Solution Approach 1:
The patent uses flexible webs (thin film structures) as the mounting substrate for the strain sensors. These flexible webs deform under torque load, allowing the mounted strain sensors to accurately detect torque while maintaining a relatively simple and compact transducer assembly structure.
Solution Approach 2:
The patent combines multiple functions into the flexible web structure: it serves as both the structural element connecting the inner hub to the outer rim and as the mounting substrate for the strain sensors. This integration reduces the number of separate components needed in the transducer assembly.
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 transducer assembly enables precise torque control, ensuring accurate application of torque to fasteners by detecting and adjusting motor speed, enhancing operational precision and reducing the risk of over-torque.
Implementation Method 1
a sensor affixed to each of the flexible webs for detecting strain of each of the flexible webs in response to a reaction torque applied to the transmission from the output shaft
Data Source
AI summary
A transducer assembly for use in a power tool. The transducer assembly including an inner hub having an aperture, the inner hub being one of either rotationally affixed to a housing or a rotatable component of a transmission via mechanical interference with the aperture, an outer rim spaced radially outward from the inner hub, the outer rim being rotationally affixed to the other of the housing or the rotatable component of the transmission, such that either the inner hub or the outer rim rotates relative to the other of the inner hub or the outer rim, a plurality of flexible webs extending outward from the inner hub to the outer rim, and a sensor affixed to at least one of the flexible webs for detecting strain of the at least one flexible web in response to a reaction torque applied to the transmission from the output shaft.