Upper Sash Detent Latch for Double-Hung Window
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Solution Overview
Problem
Double-hung windows often experience the upper sash settling or lowering from its fully raised closed position due to insufficient balance springs or interference from closing and locking the lower sash.
Innovation Solution
A latch mechanism featuring paired spring detents and latches on the side rails and upper corners of the upper sash, utilizing resilient arms and cam portions to securely hold the upper sash in its raised position while allowing for selective lowering, with spring-biased latch bolts ensuring engagement and release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the upper sash is held in its fully raised position using balance springs, then the upper sash can remain closed, but the balance springs may not be strong enough to prevent settling or lowering
Solution Approach 1:
The detent mechanism is divided into multiple spring detents (first and second spring detents) positioned at different locations, with each providing independent latching force. This segmentation distributes the holding force across multiple points rather than relying on a single strong spring, resolving the contradiction by achieving reliable position stability without requiring excessively strong individual balance springs.
Solution Approach 2:
Spring detents act as intermediary elements between the upper sash and the frame, providing a mechanical latching function that supplements the balance spring system. These detents engage with corresponding latches on the upper sash to physically prevent settling, thereby enhancing position stability without increasing balance spring strength.
2Reliability
If a detent arrangement is added to latch the upper sash in its fully raised position, then position stability is improved, but the device complexity increases
Solution Approach 1:
The spring detents are designed to automatically engage with the latches on the upper sash as the sash is raised to its fully opened position. The springs provide automatic resetting action, eliminating the need for manual intervention or complex control mechanisms. This self-service characteristic achieves reliable latching without proportionally increasing device complexity.
Solution Approach 2:
The invention replaces complex mechanical latch systems with simpler spring-based detent mechanisms. The spring detents use elastic deformation and cam surfaces rather than intricate linkages or actuating mechanisms, reducing overall device complexity while maintaining reliable position stability.
3Reliability
If the latch mechanism uses spring-biased latch bolts to engage the spring detents, then engagement reliability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The spring-biased latch bolts provide dynamic engagement capability, allowing the latches to adapt to minor variations in alignment through the elastic deformation of the springs. This dynamic characteristic compensates for manufacturing tolerances and ensures reliable engagement without requiring extremely precise manufacturing, as the springs absorb dimensional variations.
Solution Approach 2:
The spring detents utilize changes in spring compression and cam surface geometry to facilitate engagement. By designing the cam portions with appropriate angles and the springs with suitable force characteristics, the mechanism accommodates manufacturing variations while maintaining reliable latching through parameter optimization rather than requiring tight tolerances.
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
Effectively maintains the upper sash in its fully raised position without obstructing its ability to be lowered, providing a reliable and adjustable solution to prevent unwanted settling.
Implementation Method 1
Each spring detent preferably has a resilient arm positioned to be engaged by the associated latch as the upper sash is moved toward its fully raised position
Implementation Method 2
The resilient arm preferably has a cam portion that is angulated and disposed to be engaged by the associated latch as the upper sash is raised
Implementation Method 3
Each latch preferably includes a spring-biased latch bolt for camming the resilient arm of the spring detent laterally outwardly as the upper sash is raised
Data Source
AI summary
A building window includes a generally rectangular frame having an upper rail and opposed side rails. An upper sash and a lower sash are independently movably mounted in the frame. A pair of opposed spring detents are mounted on the side rails adjacent to the upper rail of the frame. A pair of laterally opposed latches are at upper corners of the upper sash at positions to engage the spring detents as the upper sash is moved to its fully raised position. The latches cooperate with the spring detents to hold the upper sash in its fully raised position and are releasable from the spring detents to permit lowering of the upper sash.