Four-Position Sash Lock Cam Mechanism for Window Control
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Solution Overview
Problem
Existing window hardware for sliding sash windows lacks an integrated solution that effectively prevents sliding and tilting while allowing for ventilation and easy cleaning, with a focus on safety to prevent egress by small children and intruders.
Innovation Solution
An integrated sash lock and tilt latch combination using a single cam mechanism with a detent mechanism, where the cam can be rotated to different positions to lock or unlock the window for sliding and tilting, incorporating a stop member to limit window travel and prevent accidental opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sash lock is mounted to prevent sliding movement, then window security is improved, but the window cannot be opened for cleaning or ventilation
Solution Approach 1:
The cam mechanism is designed to be rotatable between multiple positions (locked, tilted, vented) rather than fixed in a single state. This dynamic element allows the window to transition between security and maintenance modes, resolving the contradiction between preventing sliding movement and enabling opening for cleaning.
Solution Approach 2:
The locking mechanism is segmented into distinct functional positions: a locked position that prevents sliding, a tilted position that allows sash pivoting for cleaning, and a vented position that permits controlled opening. This segmentation enables the single device to provide both security and ease of operation for different purposes.
2Ease of operation
If a tilt latch is added to permit pivoting for cleaning, then ease of operation is improved, but the device complexity increases
Solution Approach 1:
The sash lock and tilt latch functions are merged into a single integrated device. The cam mechanism simultaneously controls both the sliding lock and the tilt latch, eliminating the need for separate components and reducing overall device complexity despite providing multiple functions.
Solution Approach 2:
The single cam-operated device performs multiple functions: it acts as a sash lock to prevent sliding, a tilt latch to enable pivoting, and a vent control to limit opening distance. This multi-functionality achieves ease of operation without proportionally increasing device complexity.
3Ease of operation
If the window is fully opened for ventilation, then ease of operation is improved, but safety is worsened due to risk of child egress
Solution Approach 1:
The vent stop member is positioned to change the parameter of window opening distance, limiting it to a predetermined distance that provides adequate ventilation while preventing full opening that would allow child egress. This parameter control resolves the contradiction between ease of operation and safety.
4Reliability
If multiple separate devices are used for locking and tilting, then reliability is improved, but device complexity increases
Solution Approach 1:
Multiple separate devices (sash lock and tilt latch) are merged into a single integrated cam-operated mechanism. This merging maintains reliability by providing both locking and tilting control while reducing device complexity by eliminating redundant components and simplifying the overall hardware configuration.
Data Source
AI summary
A sash window fastener includes a lock assembly, latch assembly, and stop member. The lock assembly mounts upon the meeting rail, and includes a pivotable cam to engage a keeper on the master frame, and a pivotable arm that acts as a follower. The arm interconnects with the latch within the meeting rail, so cam rotation controls arm positioning—causing translational movement of the latch. The cam can occupy four positions causing four corresponding latch positions: an extended position securing the cam to the keeper, with the latch engaging the master frame to prevent tilting, and contacts a first stop to redundantly lock the window; a first retracted position permitting sliding of the window, but limited by the slightly retracted latch clearing the first stop but contacting a second stop; a second retracted position permitting sliding beyond the second stop, but preventing tilting; and a third retracted position permitting tilting.