Coil Spring Torque Limiter for Distributed Friction Load
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Solution Overview
Problem
Conventional torque limiters face durability issues due to localized application of rotational torque on the coil spring, which affects their performance in sheet feeding mechanisms.
Innovation Solution
A torque limiter design featuring first and second rotators connected via a coil spring, where the rotators and coil spring surfaces have different static frictional forces, allowing integral rotation when torque is below a threshold and relative rotation when torque exceeds it, distributing torque more evenly and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the coil spring is engaged with the outer race at a single location, then the structure is simple, but the rotational torque is applied locally causing reduced durability
Solution Approach 1:
The coil spring is divided into multiple engagement locations around its circumference. Instead of a single engagement point, the spring engages with the outer race at multiple discrete points distributed circumferentially, which segments the torque application and prevents localized stress concentration.
Solution Approach 2:
Different locations of the coil spring are given different engagement characteristics by positioning engagement protrusions at multiple circumferential locations. This creates local variations in torque transmission, where each engagement point handles a portion of the total torque, distributing the mechanical stress evenly across the spring structure.
2Reliability
If the coil spring engages with the outer race at multiple locations, then durability is improved by distributing torque, but device complexity increases
Solution Approach 1:
Multiple engagement protrusions are integrated into a single outer race component, and correspondingly, multiple engagement grooves are incorporated into the coil spring. This merging of multiple engagement features into unified components achieves durable multi-point torque distribution without requiring separate assemblies for each engagement point.
Solution Approach 2:
The coil spring's own structure is utilized to provide the engagement grooves at multiple locations, eliminating the need for additional external engagement mechanisms. The spring serves both its primary function of providing torque limiting capability and the secondary function of providing multiple engagement points through its own geometric features.
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
This design increases the durability of the torque limiter by preventing localized torque application on the coil spring, ensuring consistent performance in sheet feeding mechanisms.
Implementation Method 1
a difference is provided between a maximum static frictional force between the coil spring and the first outer circumferential surface and a maximum static frictional force between the coil spring and the second outer circumferential surface
Data Source
AI summary
In a torque limiter of the present invention, a difference is provided between a maximum static frictional force between the coil spring and the first outer circumferential surface and a maximum static frictional force between the coil spring and the second outer circumferential surface such that, when rotational torque in a direction of increasing the diameter of the coil spring and less than a predetermined value is applied to the first or second rotator, the first and second rotators integrally rotate via the coil spring, and one of the first and second rotators relatively rotates relative to the other of the first and second rotators together with the coil spring when the rotational torque is greater the predetermined value.