Reversing Tension Spring Structure for Longer Pull Arrangement Life
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Solution Overview
Problem
Existing pull arrangements with tension springs in deceleration and acceleration devices tend to break after a large number of actuations, limiting their lifespan due to high stress concentrations.
Innovation Solution
A tension spring with distinct areas of high and low spring stiffness, where the high stiffness area extends around a reversing structure and the low stiffness area connects to the housing, distributing the stress and minimizing the likelihood of breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform tension spring is used in the pull arrangement, then the spring can be manufactured simply, but the spring breaks after a large number of actuations due to high stress concentrations
Solution Approach 1:
The tension spring is designed with varying cross-sectional dimensions along its length, creating local quality differences. Specifically, the spring has a first cross-sectional dimension in the region extending around the reversing structure and a second, larger cross-sectional dimension in the region connected to the housing. This local variation in geometry distributes stress more evenly, preventing breakage at high-stress regions while maintaining overall spring functionality.
2Reliability
If the spring cross-sectional dimension is increased throughout to reduce stress, then the spring lifespan is extended, but the spring stiffness becomes non-optimal for deceleration and acceleration functions
Solution Approach 1:
The spring features different cross-sectional dimensions in different regions to optimize both lifespan and stiffness. The first region (around reversing structure) has smaller dimensions for flexibility and stress distribution, while the second region (connected to housing) has larger dimensions for increased stiffness and strength. This local differentiation allows each region to perform its specific function optimally.
Solution Approach 2:
The spring is segmented into distinct regions with different cross-sectional characteristics. The first cross-sectional dimension region and second cross-sectional dimension region are clearly differentiated, allowing the spring to have varying mechanical properties along its length. This segmentation enables the spring to provide appropriate stiffness in different locations while maintaining overall reliability.
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 extends the lifespan of the pull arrangement by distributing stress evenly across the spring, allowing for a larger number of actuations without failure, while maintaining effective deceleration and acceleration functionality.
Implementation Method 1
a tension spring extending around the reversing structure is connected with one end to the carrier element and the opposite end to the housing for moving the carrier element to the end position
Data Source
AI summary
In a pull arrangement including a housing with a guide structure movably supporting a carrier element which has a park position at one end of the guide structure and a rest position at the other end and a reversing structure is provided at the other end of the guide structure and a tension spring extending around the reversing structure is connected with one end to the carrier element and the opposite end to the housing for moving the carrier element to the end position, the tension spring comprises an area of high spring stiffness where it extends around the reversing structure and an area of low spring stiffness where the spring is connected to the housing away from the reversing structure.