Casement Window Hinge Guide Arm Reduces Sash Sag

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Solution Overview

Problem

Casement window hinges face issues with sash sag due to the offset between the support point and the center of gravity, leading to deformation and difficulty in closing the window, especially under wind loads and with aging materials.

Innovation Solution

A casement window hinge design featuring a thickened thermoplastic guide arm that supports the sash against the track when closed, using a wood screw for stabilization, and an eccentric pivot mechanism to correct sash sag, with a snap-fit assembly for rapid installation and a low-friction interface to prevent accidental sash fall.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional thin guide arm is used, then the hinge structure is lightweight and simple, but the sash sags over time due to insufficient support against the track

Engineering Contradiction:

Improvesash support stabilityVSAvoidguide arm structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The guide arm incorporates a localized thickened portion at the critical support area where it contacts the track and sash. This local reinforcement provides enhanced support stability without requiring the entire guide arm to be excessively thick or complex, thus resolving the contradiction between reliability and device complexity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The guide arm is made from a composite material structure that combines a base material with reinforcing elements or layers. This composite construction allows the guide arm to achieve the necessary strength and stability to prevent sash sag while maintaining a relatively simple overall structure, addressing both reliability and complexity concerns.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the guide arm is made thicker to support the sash, then sash sag is reduced, but the manufacturing complexity and material usage increase

Engineering Contradiction:

Improvesash sag resistanceVSAvoidguide arm fabrication

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of making the entire guide arm uniformly thick, the invention applies thickness only locally at the specific area where support is needed. This localized approach reduces overall material usage and manufacturing complexity while still providing sufficient sash sag resistance, thus resolving the contradiction between reliability and ease of manufacture.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The guide arm design incorporates controlled parameter changes in thickness along its length, with specific dimensional specifications at critical locations. These parameter variations allow optimization of both strength and manufacturability, enabling sash sag resistance without excessive material consumption or manufacturing difficulty.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If traditional attachment methods are used, then assembly is straightforward, but the hinge joints loosen over time allowing increased sash tilt and sag

Engineering Contradiction:

Improvehinge joint stabilityVSAvoidattachment mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The attachment mechanism incorporates dynamic adjustment capabilities, allowing the hinge joints to be tightened or adjusted during operation to compensate for loosening over time. This dynamic feature maintains hinge joint stability without requiring an overly complex attachment mechanism, resolving the contradiction between reliability and device complexity.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The attachment system includes feedback mechanisms that allow detection and adjustment of joint looseness. This feedback capability enables maintenance of stable hinge joints over time without requiring excessive complexity in the attachment mechanism, thus addressing both reliability and device complexity concerns.

Inventive Principle:

Principle #23Feedback

4Reliability

If the guide arm is made from stronger materials to resist buckling, then sash sag is reduced, but the weight and cost increase

Engineering Contradiction:

Improveguide arm buckling resistanceVSAvoidguide arm weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The guide arm uses stronger materials or reinforced structures only at specific locations where buckling resistance is critical, rather than throughout the entire component. This localized reinforcement provides necessary buckling resistance while minimizing weight increase, resolving the contradiction between reliability and weight.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The guide arm employs composite material construction that combines lightweight materials with reinforcing elements. This approach provides buckling resistance and structural reliability while keeping the overall weight low, thus resolving the contradiction between reliability and weight.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS9080356B2Casement window hinge with reduced sash-sag

Publication Date: 2015.07.14 LASEE JACK C

AI summary

A casement window hinge protects against sash sag by providing a guide arm that substantially fills the space between the sash and the window frame when the window is closed. This space-filling guide arm may be produced with lightweight thermoplastic material whose pivoting connection to the sash arm may be strengthened through a wood screw providing an axis for the pivot that may be stabilized within the sash into which the screw is driven.