Plastic Detent Spring for Window Lock Snap-Action
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Solution Overview
Problem
Conventional all-plastic sash locks require metallic detent springs for strong and long-lasting detent mechanisms, complicating manufacturing and increasing costs due to the need for metallic components.
Innovation Solution
A unique plastic detent spring arrangement using engineering plastic material, such as Celcon®, with a closed, generally rectangular shape and a confinement structure within the lock housing enhances the snap-action effect and secure positioning, eliminating the need for metallic springs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metallic detent springs are used in all-plastic sash locks, then the detent mechanism becomes strong and long-lasting, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the material parameter from metal to plastic (acetal copolymer) for the detent spring, while compensating for the lower inherent strength through geometric optimization of the spring configuration and its interaction with the detent cam surfaces
Solution Approach 2:
The patent replaces expensive metallic springs with inexpensive plastic springs made from acetal copolymer, accepting that the plastic components may have shorter service life but achieving comparable functional performance through proper design
2Ease of operation
If metallic detent springs are used in otherwise all-plastic sash lock devices, then a strong snap-action effect is provided, but the assembly operations are complicated and costs increase
Solution Approach 1:
The patent optimizes the geometric parameters of the plastic detent spring including its thickness, width, and curvature to achieve sufficient snap-action effect without requiring metallic materials
Solution Approach 2:
The patent combines the detent spring function with the plastic housing structure through integrated molding, eliminating separate assembly steps for installing metallic springs and simplifying manufacturing
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
The solution provides a strong and noticeable snap-action feel while ensuring secure operational positioning of the locking cam, maintaining performance equivalent to sash locks with metallic springs but at reduced manufacturing complexity and cost.
Implementation Method 1
a unique form of detent spring comprised of an engineering plastic material, such as Celcon®, and is formed in a closed, preferably generally rectangular shape
Data Source
AI summary
A sash lock mechanism of all-plastic construction incorporating a plastic detent spring arrangement having operating characteristics equal or superior those of conventional metallic springs while providing a more economical manufacture and assembly. The detent spring is of closed rectangular form, with inwardly bowed side elements positioned to act on opposite sides of a detent cam positioned between them, and connected at their ends by integral end and corner elements. The end and corner elements are closely confined against outward movement, causing the inwardly bowed side elements to be significantly more resistant to outward displacement by the detent cam when operating the lock. The arrangement provides a superior “feel” and snap-action effect than expected from all-plastic detent mechanisms for the purposes intended.