Window Balance Shoe and Channel Integration
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Solution Overview
Problem
Existing window balance systems face issues with robustness and reliability due to insufficient connection between the U-shaped channel and the shoe, leading to separation or breakage, especially with heavy window sashes, and the locking mechanism is prone to retraction when surfaces are worn.
Innovation Solution
A window balance system with a locking device that includes a rotatable pawl biased to engage with a cord, providing a more robust connection by directly linking the U-shaped channel to the pivot bar, and a shoe design that enhances engagement with the pivot bar to prevent lateral movement and improve holding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the connection between the U-shaped channel and the shoe is made robust to prevent separation, then the reliability of the window balance system improves, but the device complexity increases
Solution Approach 1:
The patent combines the channel and shoe into a single integrated component, eliminating the need for separate connections and fasteners. This merging of components directly resolves the technical contradiction by providing a robust connection that prevents separation while avoiding the added complexity of multiple connection elements.
Solution Approach 2:
The patent divides the window balance system into distinct functional segments: the channel-shoe assembly, the locking device, and the balance element. This segmentation allows each component to be optimized independently while maintaining overall system reliability without excessive complexity.
2Reliability
If the locking mechanism is designed to prevent retraction when surfaces are worn, then the reliability improves, but the manufacturing precision requirements increase
Solution Approach 1:
The locking device is designed with a pawl that can dynamically adjust its engagement state based on the condition of the cord and pulley surfaces. The pawl's rotational capability allows it to maintain reliable locking even when surfaces wear over time, reducing the need for extremely precise manufacturing tolerances while ensuring long-term reliability.
Solution Approach 2:
The locking mechanism is designed to self-adjust and maintain reliable engagement without requiring external intervention or extremely precise manufacturing. The pawl's geometry and the cord's flexibility allow the system to compensate for surface wear while maintaining locking reliability.
3Strength
If the shoe is designed to directly contact the pivot bar to prevent lateral movement, then the holding strength improves, but the ease of manufacture decreases
Solution Approach 1:
By integrating the shoe directly with the channel as a single component, the patent eliminates the need for separate manufacturing and assembly processes. This merging provides direct contact between the shoe and pivot bar for maximum holding strength while simplifying manufacturing compared to assembling separate parts.
Solution Approach 2:
The shoe is designed to perform multiple functions: guiding the pivot bar, preventing lateral movement, and providing a mounting surface for the balance element. This multi-functionality in a single component achieves high holding strength while reducing the overall manufacturing complexity compared to multiple specialized parts.
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 enhances the holding strength and reliability of the window balance system by preventing undesirable retraction and improving the connection between the channel and the pivot bar, reducing the likelihood of system failure and wear-related issues.
Implementation Method 1
a fixed pulley block coupled to the first end of the U-shaped channel; a movable pulley block movably disposed in the U-shaped channel; and a cord extending between the fixed pulley block and the moveable pulley block
Implementation Method 2
a locking device coupled to the fixed pulley block and configured to engage with the cord and lock a position of the fixed pulley block with respect to the cord; the locking device includes a rotatable pawl that is biased to engage the cord with one or more teeth disposed on the pawl
Implementation Method 3
the actuator arm is biased by a compression spring
Data Source
AI summary
A window balance system includes a U-shaped channel with a first end and an opposite second end, and a balance element supported within the U-shaped channel. The balance element includes a fixed pulley block coupled to the first end of the U-shaped channel, a movable pulley block movably disposed in the U-shaped channel, and a cord extending between the fixed pulley block and the moveable pulley block. The window balance system includes a locking device coupled to the fixed pulley block and configured to engage with the cord and lock a position of the fixed pulley block with respect to the cord. The window balance system also includes a shoe coupled to the second end of the U-shaped channel. The shoe includes an elongate portion and an enlarged portion such that the shoe is substantially T-shaped, and a chamber configured to receive at least a portion of a pivot bar.