Torque Limiter Coil Spring End Restraint
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Solution Overview
Problem
Conventional torque limiters with coil springs having cut ends perpendicular to the axis can cause burrs that damage the inner ring or produce noise, and when modified to prevent contact, the end portions vibrate, leading to chatter.
Innovation Solution
The coil spring end portions are radially spaced from the inner ring and restrained by protrusions on the outer annular and lid members, reducing vibration and preventing chatter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the coil spring end portions are radially spaced from the inner ring to prevent burr contact, then damage to the inner ring is prevented, but the end portions vibrate causing chatter
Solution Approach 1:
The patent introduces restraining protrusions as intermediary elements between the coil spring end portions and the outer annular member/lid member. These protrusions engage with recesses in the coil spring ends, providing stabilization without requiring the ends to contact the inner ring, thus preventing both burr damage and vibration-induced chatter
Solution Approach 2:
The patent moves the stabilization mechanism from the radial dimension (preventing contact with inner ring) to the axial dimension (using restraining protrusions that extend axially to engage with coil spring recesses). This dimensional shift allows the end portions to be radially spaced for burr prevention while being axially restrained to prevent vibration
2Power
If the coil spring is fitted with interference fit on the inner ring, then torque is generated through radial expansion, but burrs at cut ends damage the inner ring surface
Solution Approach 1:
The patent extracts the harmful burrs from the interaction zone by radially spacing the coil spring end portions from the inner ring surface. The restraining protrusions are positioned to stabilize the spring ends without contacting the inner ring, effectively removing the source of burr damage while preserving the torque-generating interference fit between the spring and inner ring
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 arrangement prevents damage to the inner ring, reduces noise, and stabilizes the torque limiter by effectively restraining the coil spring end portions, enhancing its operational stability.
Implementation Method 1
a coil spring 14 having a constant diameter and fitted on the radially outer surface of the inner ring 13 with an interference fit... whereby a predetermined torque is generated due to radial expansion of the coil spring 14 when the outer annular member 11 and the inner ring 13 rotate relative to each other
Data Source
AI summary
In a spring type torque limiter, it is proposed to prevent cut end portions of a coil spring fitted on an inner ring from causing chatter of the torque limiter, even if the cut end portions of the coil spring are separated from a radially outer surface of the inner ring in order to prevent burrs remaining on the cut end portions of the coil spring from contacting the radially outer surface of the inner ring. The first cut end portion of the coil spring fitted on the inner ring is inserted in a recess of a first spring receiving protrusion formed on the radially inner surface of the outer annular member. The second cut end portion is inserted in a recess of a second spring receiving protrusion formed on the inner surface of the lid member, thereby restraining the first and second cut end portions with the recesses.