Forced-Entry-Resistant Sash Lock with Cam Translation
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Solution Overview
Problem
Existing window locks are inadequate in resisting forced entry from the exterior, particularly in preventing unauthorized manipulation of the cam to unlock the window.
Innovation Solution
A forced-entry-resistant sash lock design featuring a housing, shaft, cam, and separation member, which allows selective rotational and translational movement to engage and disengage with a keeper, incorporating a leaf spring for biasing the cam into locked and unlocked positions, preventing forced rotation and translation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional sash lock with a rotatable cam is used, then the window can be locked in a closed position, but the lock can be easily manipulated from the exterior to unlock the window
Solution Approach 1:
The lock mechanism is divided into separate functional components: a cam for locking, a keeper for engagement, a shaft for operation, and a housing for protection. This segmentation allows each component to be optimized for its specific function while working together to provide secure locking that resists external manipulation.
Solution Approach 2:
The cam is positioned within the housing cavity, with the shaft rotating within the housing to control cam movement. The cam engages the keeper from within the protected interior space, creating a nested arrangement where the locking mechanism operates inside the housing while providing external security.
2Ease of operation
If the cam is made accessible for operation, then the window can be easily locked and unlocked, but the cam becomes vulnerable to external manipulation and forced entry
Solution Approach 1:
The shaft acts as an intermediary element that transmits the user's locking action to the cam while remaining protected within the housing. The shaft rotates within the housing cavity, converting external user input into controlled internal cam movement, thus mediating between ease of operation and protection from manipulation.
Solution Approach 2:
The locking action is transferred from a direct external manipulation of the cam to a rotational movement of the shaft within the housing. This dimensional transformation allows the user to operate the lock easily through shaft rotation while the cam remains protected and controlled within the housing cavity.
3Reliability
If the cam is protected from external access, then forced entry is prevented, but the locking mechanism becomes more complex
Solution Approach 1:
The housing, shaft, cam, and keeper are merged into a single integrated locking system where the housing protects the cam and shaft assembly, which in turn controls the keeper engagement. This merging of components achieves security without requiring multiple separate complex mechanisms.
Solution Approach 2:
The housing serves multiple functions: it protects the cam from external manipulation, provides a mounting structure for the shaft, and defines the interior cavity where the locking mechanism operates. This multi-functionality reduces the need for additional separate components, simplifying the overall design while maintaining security.
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 secures the window by preventing forced entry and unauthorized operation from the outside, ensuring the cam remains locked in a secure position against external manipulation.
Implementation Method 1
incorporating a leaf spring for biasing the cam into locked and unlocked positions
Data Source
AI summary
A forced-entry resistant sash lock includes a housing, a shaft pivotally mounted to the housing, a cam mounted on the shaft using an elongated opening permitting selective rotational and translational movements, and a separation member secured to the shaft. In the unlocked position, upon shaft rotation in a first direction a cam surface on the separation member engages a follower surface on the cam causing co-rotation of the cam into a non-forced entry-resistant locked position, and upon continued rotation the cam surface moves relative to the follower surface causing cam translation into a forced-entry-resistant locked position through movement of the shaft within the elongated opening, until an engagement surface of the separation member engages a contact surface of the cam, preventing forced reverse cam translation. The cam translation causes a cam stop surface to engage a housing stop surface preventing forced cam counter-rotation.