Powered Screwdriver Clutch Sensing for Precise Torque Setting
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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 adjust and limit torque, which can result in damage or stripping of threads.
Innovation Solution
A rotary power tool with a clutch mechanism incorporating a compression spring and an inductive sensor, where the clutch adjustment assembly allows for adjustable torque settings through a rotatable collar, and an electronic control unit determines the clutch parameter based on the inductive sensor's output, enabling precise torque control and preventing over-tightening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a clutch mechanism with compression spring is used to limit torque, then torque control capability is improved, but measurement precision of torque setting is insufficient
Solution Approach 1:
The patent replaces the traditional mechanical torque measurement method with an inductive sensor-based detection system. The inductive sensor detects the position of the compression spring non-contactly, converting mechanical displacement into electrical signals for precise digital measurement and control of torque settings.
Solution Approach 2:
The patent implements a feedback mechanism where the inductive sensor continuously monitors the compression spring position and sends signals to the electronic control unit. This closed-loop feedback system enables real-time adjustment and precise control of torque settings, ensuring accurate measurement and control.
2Adaptability or versatility
If manual adjustment of clutch spring length is allowed, then adaptability of torque settings is improved, but reliability is reduced due to potential inadvertent changes
Solution Approach 1:
The patent implements an automatic lockout feature that detects when the power tool is in operation and automatically prevents adjustment of the clutch spring length. This self-protecting mechanism eliminates the need for manual locking procedures and reliably prevents inadvertent setting changes during use.
Solution Approach 2:
The electronic control unit receives feedback from operational status sensors and automatically activates the lockout mechanism when the tool is running. This feedback-based control ensures that torque settings remain stable during operation while still allowing adjustments when the tool is idle.
3Measurement precision
If inductive sensor is positioned to detect compression spring movement, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent integrates the inductive sensor directly into the collar assembly that already exists for manual adjustment of the clutch spring. By merging the sensing function with the existing adjustment structure, the patent achieves precise measurement without adding separate complex sensor mounting mechanisms.
Solution Approach 2:
The patent uses the magnetic field of the inductive sensor as an intermediary to detect compression spring position non-contactly. This eliminates the need for direct mechanical contact between the sensor and spring, simplifying integration while maintaining high measurement 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
The solution provides precise control over torque application, preventing over-tightening and allowing users to select between low, high, or variable torque settings, ensuring accurate and safe fastening operations.
Implementation Method 1
an inductive sensor disposed within the collar and 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 includes a gear case, an output shaft, a drive mechanism, and a clutch mechanism. The clutch mechanism including a compression spring positioned around the output shaft. The rotary power tool further includes a clutch adjustment assembly having a collar disposed circumferentially around the gear case and rotatable to adjust a length of the compression spring, an inductive sensor disposed within the collar and 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, and an electronic control unit configured to receive an output signal from the inductive sensor indicative of the change in inductance in the inductive sensor and to determine a parameter of the clutch mechanism based on the output signal. The compression spring is disposed adjacent and offset from the inductive sensor.