Window Opening Limit Device Automatic Reset Mechanism
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Solution Overview
Problem
Window opening limit devices (WOLDs) fail to automatically reset when a window is closed, and they do not meet the enhanced safety and security requirements set by recent building codes, such as ASTM International's Standard F2090-10, which necessitates automatic reset, resistance to inadvertent egress or intrusion forces, and easy disengagement by a disabled user using a single hand.
Innovation Solution
A window opening limit device featuring a slider, a button that moves between retracted and projected positions, and a spring that biases the button toward the projected position, allowing automatic reset when the window is closed, with a bezel and return spring for additional functionality, ensuring engagement and disengagement mechanisms that meet safety and security standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a window opening limit device is installed to prevent inadvertent egress or intrusion, then safety and security are improved, but the device fails to automatically reset when the window is closed, requiring manual intervention
Solution Approach 1:
The device automatically resets itself when the window is closed by utilizing the window's movement to trigger the reset mechanism. The button is spring-biased to return to its projected position automatically, eliminating the need for manual intervention and enabling the device to serve itself.
Solution Approach 2:
The button is pre-positioned in a projected state that engages with the window sash to limit opening. When the window closes, the mechanism is preliminarily set to automatically return the button to its limiting position, preparing the safety function for the next opening cycle without user action.
2Ease of operation
If the button is spring-biased toward the projected position to enable automatic reset, then ease of operation is improved, but the device may inadvertently disengage under force, compromising safety
Solution Approach 1:
The button is designed to be dynamically responsive, spring-biased to project automatically when the window closes, yet mechanically engaged to resist displacement under force during operation. This dynamic behavior allows automatic reset while maintaining security during the window opening cycle.
Solution Approach 2:
The button's positional parameter changes automatically through the spring bias mechanism, transitioning from retracted to projected position based on window state. This parameter change enables automatic reset while the mechanical engagement maintains resistance to unauthorized displacement.
3Reliability
If the button projects beyond the front surface to engage the window sash, then the limiting function is effective, but the device complexity increases with additional components like bezel and return spring
Solution Approach 1:
The button, slider, and spring mechanism are merged into an integrated assembly where the slider houses the button and the spring is contained within the same structure. This merging reduces the number of separate components while maintaining the projected engagement function for effective window limiting.
Solution Approach 2:
The button is nested within the slider assembly, and the spring is nested within the housing structure. This nesting arrangement allows multiple functional components to occupy the same space, reducing overall device complexity while maintaining the projected engagement capability.
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 device effectively limits window opening while ensuring automatic reset and easy disengagement, meeting enhanced safety and security standards by allowing the window to open fully and then automatically resetting when closed, preventing inadvertent egress or intrusion.
Implementation Method 1
a projecting spring for biasing the button toward the projected position
Implementation Method 2
a return spring for biasing the slider toward the first position
Data Source
AI summary
A method of operating a window having a sash and a window opening limit device includes moving the sash from a closed position to a limited position. When in the limited position, the window opening limit device is in a projected position, and the sash is engaged with the window opening limit device. Moving the window opening limit device to a retracted position disengages the sash and the window opening limit device. The sash may then be moved from the limited position to an open range. When the sash is returned to the closed position, the window opening limit device automatically returns to the projected position, and the sash is disengaged with the window opening limit device.