Tilt-In Window Brake Shoe With Shielded Ribbon Spring
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Solution Overview
Problem
Existing counterbalance systems for tilt-in windows, particularly those with vinyl frames, face issues such as increased friction and contamination due to large brake shoe housings, which lead to sticking and wear, and inadequate engagement with the rear wall of the window track, resulting in inefficient operation and reduced lifespan.
Innovation Solution
A counterbalance system featuring a brake shoe chassis with ribbon spring coils, protected by external and internal barriers, and a cam-based brake mechanism that engages the side and rear walls of the guide track, minimizing contamination and wear while ensuring secure locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If multiple smaller spring coils are ganged together to provide needed counterbalance force for heavier window sashes, then the counterbalance force is sufficient, but the brake shoe housing must be large enough to accommodate the springs, increasing friction and causing the brake shoe to stick in place
Solution Approach 1:
The patent places the spring coils inside a nested housing structure that is integrated into the brake shoe assembly. The housing contains the springs in a compact arrangement, allowing multiple spring coils to be accommodated without significantly increasing the external dimensions of the brake shoe. This nesting approach maintains sufficient counterbalance force while minimizing the brake shoe's surface area and friction with the guide track.
2Volume of moving object
If the brake shoe housing is made large to accommodate multiple spring coils, then the springs can be properly housed, but the brake shoe generates greater friction and is more likely to stick in place
Solution Approach 1:
The spring coils are nested within a compact housing structure that is part of the brake shoe assembly. This nested arrangement allows multiple spring coils to be contained within a minimized volume, reducing the brake shoe's external dimensions and consequently its friction contact area with the guide track, while still providing sufficient housing space for the springs.
3Volume of moving object
If the brake shoe housing is made large to accommodate spring coils, then the springs can be retained, but the brake shoe has large surface area that accumulates contamination from construction byproducts
Solution Approach 1:
The spring coils are nested within a compact housing structure that minimizes the brake shoe's external surface area. This reduced surface area decreases the amount of contamination that can accumulate on the brake shoe from construction byproducts such as sawdust and drywall dust, while still providing adequate internal space for the spring coils.
4Force
If a single large spring coil is used for heavier window sashes, then the counterbalance force is sufficient, but the space restrictions in modern tilt-in window assemblies prevent the use of larger springs
Solution Approach 1:
The patent combines multiple smaller spring coils into a single brake shoe assembly, merging their individual counterbalance forces to achieve the total required force for heavier window sashes. This merging approach allows the necessary counterbalance force to be generated within the limited space available in modern tilt-in window assemblies, as the combined effect of multiple small springs achieves the same force output as a single large spring would require.
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 system reduces friction and wear, prevents contamination, and enhances the locking mechanism by engaging three surfaces of the guide track, resulting in smoother operation and extended lifespan of the window components.
Implementation Method 1
Spring coils are constant force springs, made from wound lengths of metal ribbon. The spring coils supply the counterbalance force needed to suspend the weight of the window sash.
Implementation Method 2
The shoe, therefore, locks the tilt post in place and prevents the base of the sash from moving up or down in the window frame once the sash is tilted open.
Data Source
AI summary
A counterbalance system for a window sash that engages a guide track in a vinyl tilt-in window. At least one ribbon spring coil is used to create the counterbalance force. The ribbon spring coils are held in a brake shoe chassis that travels within the guide track of the window. A first protective barrier is attached to the brake shoe chassis. The first protective barrier travels externally of the guide track and shields the slot opening adjacent the spring placement area. A second protective barrier is attached to the brake shoe chassis inside the guide track. The second protective barrier shields the spring placements areas from contamination within the guide track. A brake mechanism is also attached to the brake shoe chassis. The brake mechanism uses a cam to spread arms against the side walls of the guide track when the window sash is tilted. This provides contact against three inside walls of the guide track, therein creating a lock.