Curl Spring Window Balance Shoe with Mounting Bracket
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Solution Overview
Problem
Existing counterbalance systems for vertically movable window sashes lack convenience and reliability in assembly and disassembly, particularly in shipping and installation, and do not effectively utilize the curl spring mechanism for enhanced locking and friction.
Innovation Solution
A mounting bracket system that remains assembled during shipping with a shoe cassette containing a curl spring, automatically disengaging when secured to a sash jamb channel, and features interchangeable shoe cassettes with tilt lock cams and locking pads for increased friction and versatility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the mounting bracket is assembled with the shoe cassette during shipping, then shipping space is saved and assembly is simplified, but the mounting bracket cannot be automatically disengaged from the shoe cassette during installation
Solution Approach 1:
The mounting bracket is designed with a mounting plate and a bracket body that can separate from each other. The mounting plate remains attached to the shoe cassette during shipping, while the bracket body can be detached and repositioned during installation to engage with the jamb channel, enabling both simplified shipping and convenient installation.
Solution Approach 2:
The mounting bracket incorporates a spring-loaded mechanism that allows the bracket body to be held in a retracted position during shipping and then automatically extend or be easily positioned during installation to engage with the jamb channel, providing dynamic adaptability between shipping and installation states.
2Adaptability or versatility
If the shoe cassettes are made with identical unhanded halves, then installation flexibility on either side of the window sash is improved, but the locking mechanism must be redesigned to ensure proper engagement
Solution Approach 1:
While the shoe cassette halves are identical in overall shape for versatility, the locking cam and locking pad are designed with asymmetric engagement features that ensure proper orientation and engagement regardless of which side the cassette is installed on, maintaining simplicity while enabling bidirectional installation.
Solution Approach 2:
The identical shoe cassette halves serve multiple functions: they provide the structural body of the shoe, contain the curl spring mechanism, and interface with both the mounting bracket and the jamb channel in the same manner regardless of installation side, simplifying inventory while maintaining installation flexibility.
3Reliability
If locking pads are added to the shoes to increase locking friction, then the locking reliability is improved, but the manufacturing cost and complexity increase
Solution Approach 1:
Instead of adding complex locking pads throughout the shoe structure, a simple friction pad is placed locally at the specific contact point where the shoe engages with the jamb channel. This localized approach provides the necessary friction enhancement while keeping the overall manufacturing process simple and cost-effective.
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
Enables convenient and reliable assembly of counterbalance systems, enhances locking friction, and allows for flexible installation of shoe cassettes on either side of the window sash, improving the overall performance and usability of the counterbalance mechanism.
Implementation Method 1
The mounting bracket is robust enough, and well enough braced and interlocked at the top 12 of shoe body 11, to hold itself and curl spring 30 in place in an assembled cassette 10 during shipment
Implementation Method 2
lower regions of shoe bodies 11a and 11b to expand or splay apart in response to rotation of locking cam 20
Implementation Method 3
The improved system also allows locking pads to be inexpensively installed on the shoes to exert increased locking friction when a sash tilts and shoe cams lock the shoes in their channels
Data Source
AI summary
A curl spring sash shoe cassette improves upon the suggestions of U.S. Pat. Nos. 5,353,548 and 5,463,793 by providing a mounting bracket that holds an uncurled length of the curl spring and is securely mounted on top of the shoe cassette to maintain an assembly of the shoe body, the curl spring, and the mount during shipment to a window manufacturer. The mount can receive two mounting screws to resist torque caused by curl springs and sash weight. The shoe is also improved to facilitate removal and reinsertion of sash pins into the tilt lock cams of the shoes and ensure that shoe body halves do not rotate relative to each other when sash tilting splays the body halves apart to lock them in a shoe channel.