Jamb-Mounted Sash Limiter with Hexalobular Security Screw
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Solution Overview
Problem
Current casement window opening limiters are not tamper-resistant and require easy detachment, complicating manufacturing and making them unsuitable for narrower windows, as they depend on the window width and hinge type for mounting, and often compete with the hinge for space.
Innovation Solution
A jamb-mounted sash limiter system that uses a security screw with a hexalobular drive to secure the limiter arm to a stud, allowing rotation and preventing further opening by engaging with a track or screw, ensuring consistent operation across various window widths and hinge types, while allowing maintenance access with a special tool.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sill-mounted limiter is used, then the opening distance can be restricted, but the mounting location must vary with window width and hinge type, complicating manufacturing
Solution Approach 1:
The patent applies universality by designing a jamb-mounted limiter that can be installed at a standard location on all window types regardless of width or hinge configuration. The limiter device is positioned on the jamb rather than the sill, allowing it to serve as a universal mounting solution across different window specifications without requiring customization of mounting location.
2Reliability
If a sill-mounted limiter is used, then opening restriction is achieved, but it competes for space with the hinge or operator on narrow windows
Solution Approach 1:
The patent resolves the space conflict by transitioning from a sill-mounted (horizontal plane) approach to a jamb-mounted (vertical plane) approach. This dimensional change allows the limiter to be positioned on the vertical jamb surface, utilizing unused vertical space that does not interfere with hinge placement or operator access on narrow windows.
3Reliability
If a security screw with hexalobular drive is used, then tamper resistance is improved, but ease of maintenance is reduced
Solution Approach 1:
The patent applies local quality by using different screw types in different locations: security screws with hexalobular drives are used in positions requiring tamper resistance, while standard screws are used in positions requiring frequent maintenance access. This differentiated approach allows the limiter arm to be securely attached where needed while remaining easily serviceable where maintenance is required.
Data Source
AI summary
A sash limiter assembly for limiting the distance a casement window can be opened. In a jamb mounted version, the limiter is mounted in one constant location on the jamb rather than multiple locations on the sill which results in the opening distance being essentially the same for all window widths and all hinge types. In both the jamb mounted version and a sill mounted version, a hexalobular or other security screw can be used to retain a limiting arm to a stud attached to a bracket, or a stud attached to a slider which slides on a track to inhibit unauthorized removal of the limiter arm.