Curl Spring Frictional Drop Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing counterbalance systems for window sash require a wide range of counterbalance forces to accommodate varying sash weights, leading to increased manufacturing costs due to the need for multiple force options to prevent 'hop' and 'drop' issues.
Innovation Solution
The use of high friction coefficient bearing surfaces in curl spring holders, which differentiate frictional resistance between uncurling and re-curling motions, allowing a single counterbalance force to effectively balance a wider range of sash weights without causing 'hop' or 'drop', by increasing resistance to uncurling while maintaining ease of raising.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wide range of counterbalance forces is provided to accommodate varying sash weights, then the system can prevent hop and drop issues, but manufacturing costs increase
Solution Approach 1:
The bearing surface is given a higher coefficient of friction than the rest of the holder by using a different material or surface treatment. This localized change in friction characteristics creates asymmetric frictional resistance that prevents hop and drop without requiring multiple counterbalance force options, thereby reducing manufacturing costs while maintaining reliability
Solution Approach 2:
The invention changes the friction parameter of the bearing surface to create asymmetric resistance during spring uncurling and re-curling. By modifying this physical parameter, the system achieves better control over sash movement and prevents hop and drop issues with a single counterbalance force option
2Reliability
If the bearing surface has high friction to increase resistance to uncurling, then drop is prevented, but resistance to re-curling also increases
Solution Approach 1:
The system exploits the dynamic difference between uncurling and re-curling motions. During uncurling, the sash weight and spring force create conditions where high friction prevents drop. During re-curling, the lifting effect changes the contact dynamics, reducing the impact of high friction and maintaining ease of operation
Solution Approach 2:
The invention converts the potentially harmful effect of high friction (which would normally resist both uncurling and re-curling equally) into a beneficial asymmetric resistance. The high friction surface, combined with the dynamic motion differences, creates beneficial resistance during uncurling to prevent drop while maintaining acceptable ease of operation during re-curling
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 solution reduces the number of different counterbalance forces needed, lowering manufacturing costs by ensuring a sash remains balanced across various weights without hopping or dropping.
Implementation Method 1
The moving contact between the bearing surface and the curled up coils produces friction that differs slightly between uncurling and re-curling motion
Data Source
AI summary
Window sash counterbalances using curl springs and holders can increase resistance to sash drop without causing sash hop by using a high coefficient of friction bearing surfaces against which curled up coils of curl springs slide when uncurling or re-curling. The higher friction bearing material produces more frictional resistance to spring uncurling than to spring re-curling and thus resists drop without causing hop. This allows a wider range of sash weights to be counterbalanced by a fewer number of counterbalance forces, saves manufacturing cost.