Window Balance Sash Support Bracket for Spring Force Compensation
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Solution Overview
Problem
Moving coil, constant force window balance assemblies with curl springs fail to provide sufficient counter-balance or holding force when the curl spring is retracted to a minimum length, leading to inability to retain the window sash in open or closed positions.
Innovation Solution
Incorporation of a sash support bracket that supplements the counter-balance force provided by the curl spring, which is fastened to the jamb wall and selectively engages the carrier, ensuring the window sash remains in position and providing feedback through audible and tactile responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the curl spring is retracted to minimum length, then the window balance assembly is compact, but the spring force drops below the rated constant force value
Solution Approach 1:
The sash support bracket acts as a counterweight mechanism by engaging the carrier and providing additional upward force through its connection to the jamb. When the curl spring is fully retracted and cannot provide sufficient force, the bracket's mechanical engagement with the carrier creates a lever arm that generates compensating upward force to maintain the sash in the fully open position.
Solution Approach 2:
The sash support bracket serves as an intermediary component between the curl spring system and the sash carrier. It mediates the force transmission by receiving force from the curl spring mounting system and transferring it to the carrier, while also providing mechanical advantage through its bracket geometry to compensate for insufficient spring force at minimum retraction.
2Adaptability or versatility
If the curl spring provides constant force over extended range, then the window sash can be retained at any position, but the spring must maintain minimum force even when fully retracted
Solution Approach 1:
The system transitions from a static spring force model to a dynamic force compensation model. The sash support bracket introduces a mechanical advantage system that dynamically adjusts the effective force based on the carrier position. When the carrier is in the fully open position and the spring is fully retracted, the bracket's geometry provides maximum mechanical advantage to compensate for the reduced spring force, ensuring reliable sash retention across the entire range of motion.
3Force
If a sash support bracket is added to supplement counter-balance force, then the holding force is improved, but the device complexity increases
Solution Approach 1:
The sash support bracket is designed to perform multiple functions: it provides structural support for the curl spring mounting, acts as a force amplification mechanism through its lever arm geometry, and serves as a positional stop for the carrier. By integrating these functions into a single component rather than adding separate elements, the design minimizes complexity while achieving the required force supplementation.
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 sash support bracket effectively prevents the window sash from drifting downward under gravity, ensuring stability and usability even when the curl spring's force is below the rated value, enhancing the functionality of the window balance assembly.
Implementation Method 1
a curl spring which produces a constant force or tension of a recommended or rated value as it is linearly extended (i.e., uncurled) and retracted (i.e., curled)
Implementation Method 2
prevent the sash from drifting downward under the force of gravity
Data Source
AI summary
A moving coil, constant force, curl spring window balance assembly for installation in a hung window assembly comprising a sash is disclosed. The window balance assembly can include a carrier, a mounting bracket, a curl spring and a sash support bracket. The sash support bracket can be positioned intermediate the carrier and the mounting bracket. The sash support bracket can selectively engage at least one of the carrier or the mounting bracket. The sash support bracket is operable to supplement the counter-balance or holding force provided by the curl spring of the window balance assembly against the weight of the sash when the sash is in a raised position.