Side Action Flush Lock for Casement Windows
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Solution Overview
Problem
Existing casement window locks protrude significantly from the window frame due to internal driving mechanisms, and there is a lack of designs that achieve low profile flush mounting with over-center security to prevent back driving.
Innovation Solution
A casement window lock with a flush-mounted design that incorporates a longitudinal slot for a fork component, a restrictor arm, and multiple pivoting points forming an over-center linkage, allowing the handle to rotate and move the fork component horizontally within the slot, while maintaining a low profile and preventing back driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a traditional internal driving mechanism is used in the lock handle, then the locking function is achieved, but the lock handle protrudes significantly (20-25 mm) from the window frame
Solution Approach 1:
The patent changes the dimensional arrangement by positioning the pivot point laterally at the edge of the lock body rather than internally. This allows the handle to rotate in a plane perpendicular to the fork component, reducing the protrusion depth while maintaining the locking mechanism's functionality through a different spatial configuration.
Solution Approach 2:
The patent introduces a restrictor arm as an intermediary component that connects the handle to the fork component. This restrictor arm with its lateral pivot point acts as a mediator that transfers the rotational motion of the handle to the fork component while enabling a more compact overall structure with reduced protrusion.
2Length of stationary object
If the lock handle is reduced to low profile flush mounting (8 mm), then aesthetics and frame integration are improved, but the mechanism to prevent back driving becomes more complex
Solution Approach 1:
The patent employs an over-center linkage mechanism that dynamically changes the position of the fork component relative to the lock bar during operation. The linkage transitions from one stable position to another through an unstable intermediate state, creating automatic engagement that prevents back driving while maintaining a compact flush-mounted structure.
Solution Approach 2:
The over-center linkage is designed to preemptively prevent back driving by creating an mechanical barrier before reverse motion can occur. The geometry of the linkage ensures that once the locked position is achieved, any attempt to reverse the motion is blocked by the over-center configuration, providing inherent security against forced opening.
3Length of stationary object
If the handle rotates in a plane perpendicular to the fork component, then the profile is reduced, but the motion transmission mechanism becomes more complex
Solution Approach 1:
The patent resolves the motion transmission complexity by changing the rotational plane of the handle to be perpendicular to the fork component rather than parallel. This dimensional change allows the use of a simple lateral pivot point at the edge of the lock body, converting a potentially complex internal transmission into a straightforward rotational motion that directly actuates the restrictor arm and fork component.
Data Source
AI summary
A low profile actuating window lock for casement windows having a longitudinal slot in a sidewall of the casing for the lock, wherein a fork component translates within the slot in a direction perpendicular to an axis of rotation of the handle and the handle rotates along a plane perpendicular to the fork component, the handle pivotable about a restrictor arm that pivots relative to the casing, allowing the handle to rotate fully from the locked position to the unlocked position with low clearance from the window frame. The pivot points of the handle and restrictor arm configuration allow for an over center linkage that prevents back driving the casement window lock.