Powered Screwdriver Clutch Sensor for Accurate Torque Limiting
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Solution Overview
Problem
Powered screwdrivers lack precise control over torque application, often leading to over-tightening of fasteners due to the inability to accurately limit and adjust torque settings, which can result in damage or inefficiency in various applications.
Innovation Solution
A rotary power tool with a clutch mechanism incorporating a compression spring and an electronic control unit that utilizes sensors to determine torque settings based on strain or inductive signals, allowing for adjustable torque settings and preventing over-tightening by deactivating the tool upon reaching a set torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clutch mechanism with compression spring is used to limit torque, then torque limiting capability is improved, but torque setting precision deteriorates due to inability to accurately measure and adjust torque settings
Solution Approach 1:
The patent applies feedback by using sensors (strain gauges or inductive sensors) to detect the actual torque setting through strain on the gear case neck portion or position of the compression spring. This detected information is fed back to an electronic control unit that adjusts the motor controller to achieve precise torque control, creating a closed-loop system that resolves the precision issue while maintaining reliability
Solution Approach 2:
The patent replaces the purely mechanical torque adjustment mechanism with an electronically controlled system. The motor controller receives signals from sensors and electronically adjusts motor output torque, substituting mechanical precision requirements with electronic measurement and control, thereby achieving higher torque setting precision
2Adaptability or versatility
If torque adjustment mechanism is added to improve torque control, then torque adjustability is improved, but device complexity increases due to additional components
Solution Approach 1:
The patent makes the compression spring and gear case neck portion serve multiple functions: the compression spring provides both torque limiting mechanical function and position sensing target for inductive sensors, while the gear case neck portion serves both structural support and strain measurement location. This multi-functionality reduces the need for separate dedicated components, thereby limiting complexity increase
Solution Approach 2:
The patent uses the compression spring as an intermediary element that translates motor torque output into measurable mechanical displacement or strain. This intermediary allows the electronic control system to indirectly measure and control torque through spring position or gear case strain, avoiding the need for direct torque sensors and simplifying the overall system architecture
3Measurement precision
If sensors are added to detect torque settings, then torque measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses the compression spring as an intermediary that converts torque into measurable mechanical displacement. Inductive sensors detect the position of this spring, providing indirect but precise torque measurement without requiring complex direct torque sensing mechanisms. The spring acts as a mechanical transducer that simplifies the measurement system
Solution Approach 2:
The patent replaces complex mechanical torque measurement mechanisms with electronic sensors that detect mechanical position or strain. By using strain gauges on the gear case or inductive sensors detecting spring position, the system substitutes mechanical measurement complexity with simpler electronic sensing and signal processing
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 precise and adjustable torque application, preventing over-tightening and ensuring accurate fastening in various applications by providing real-time feedback and automatic torque limiting.
Implementation Method 1
a sensor positioned on a neck portion of the gear case subject to strain imparted by the compression spring
Implementation Method 2
an inductive sensor proximate the compression spring such that a voltage is induced in the inductive sensor in response to relative movement between the compression spring and a magnetic field emitted by the inductive sensor
Data Source
AI summary
A rotary power tool including a gear case, an output shaft extending from the gear case, and a drive mechanism configured to provide torque to the output shaft, causing the output shaft to rotate. The rotary power tool further includes a clutch mechanism between the output shaft and the drive mechanism. The clutch mechanism includes a compression spring and is configured to limit the amount of torque provided by the output shaft. The rotary power tool further includes a sensor positioned on a neck portion of the gear case subject to strain imparted by the compression spring, and an electronic control unit configured to receive an output signal from the strain gauge and determine a torque setting of the clutch mechanism based on the output signal.