Torque Screwdriver Freewheel Mechanism for Low-Torque Tightening
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Solution Overview
Problem
Existing torque screwdrivers suffer from reverse resistance issues in their mechanical ratchet mechanisms, which can result in inadequate tightening torque and failure to engage loose screw connections, especially when low tightening torques are required.
Innovation Solution
A torque screwdriver with a freewheel mechanism that allows for resistance-free reverse rotation and includes a clutch system with helical gear teeth and a compression spring to control torque transmission, along with a switchable freewheel mechanism for setting torque in one or both rotational directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical ratchet mechanism is used to transmit rotational force in one direction, then torque transmission is achieved, but reverse resistance occurs that prevents effective tightening of low-torque screw connections
Solution Approach 1:
The patent extracts the ratchet mechanism from the torque screwdriver design, replacing it with a freewheel mechanism. This removal eliminates the reverse resistance problem while maintaining unidirectional torque transmission capability, allowing the output shaft to rotate freely in the reverse direction without resistance.
Solution Approach 2:
Instead of using a mechanism that blocks reverse rotation (ratchet), the patent inverts the approach by using a freewheel mechanism that explicitly enables free reverse rotation while maintaining forward torque transmission. This inversion resolves the contradiction by accepting reverse freedom as the solution rather than trying to maintain bidirectional control.
2Reliability
If a ratchet mechanism with reverse resistance is used, then controlled torque transmission is achieved, but the tightening torque becomes insufficient for loose screw connections
Solution Approach 1:
The ratchet mechanism that limits torque transmission is extracted and replaced with a freewheel mechanism. This allows the full tightening torque to be transmitted to the screw connection without being reduced by ratchet reverse resistance, enabling effective tightening even of loose screw connections with low torque requirements.
3Ease of operation
If a switchable ratchet mechanism is used to enable resistance-free reverse, then re-gripping comfort is improved, but the mechanism complexity increases
Solution Approach 1:
The complex switchable ratchet mechanism is extracted and replaced with a simpler freewheel mechanism. The freewheel inherently provides resistance-free reverse rotation without requiring switching capabilities, thereby reducing mechanism complexity while maintaining the ease of re-gripping benefit.
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 efficient tightening of loose screws and nuts with low tightening torque requirements by eliminating reverse resistance, allowing for comfortable re-gripping and precise torque control.
Implementation Method 1
The first clutch part interacts with the second counter clutch part and is loaded by the compression spring
Implementation Method 2
The two clutch elements move away from one another along the contact surfaces at the teeth. This movement takes place against the spring force of the compression spring
Data Source
AI summary
A torque screwdriver includes a handle and a display for a torque which has been set, and has an output. A setting device for setting a torque and a torque mechanism in the handle, the torque mechanism including a driveshaft for transmitting a torque and a release mechanism for interrupting a transmission of torque when a torque which has been set is reached. The driveshaft and the output are coupled via a freewheel mechanism.