Insert-Molded Torsion Bar Hinge With No Free Play
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Solution Overview
Problem
Existing torsion hinges require multiple parts, assembly steps, and additional operations, leading to issues like free play, neutral angle tolerance, and cosmetic exposure, necessitating a compact design without sleeves or bushings and eliminating riveting and forming operations.
Innovation Solution
An insert molded torsion bar hinge design where the torsion bar is embedded within the hinged elements, formed in a single injection molding process, eliminating the need for separate parts and ensuring consistent performance by setting the neutral angle during molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional torsion hinges use multiple separate parts (hinge leaves, torsion bars, sleeves, bushings), then assembly flexibility is improved, but device complexity and assembly steps increase
Solution Approach 1:
The patent combines multiple separate components (hinge leaves, torsion bars, sleeves, bushings) into a single integrated molded hinge assembly. The hinge leaves are molded with integrated torsion bar receptacles and mounting features, eliminating the need for separate sleeves and bushings, thus reducing part count while maintaining assembly flexibility through the molded-in design.
Solution Approach 2:
The molded hinge leaves serve multiple functions simultaneously: they provide structural support, contain integrated torsion bar receptacles, include mounting features for attachment, and incorporate neutral angle setting mechanisms. This multi-functionality eliminates the need for separate dedicated components for each function.
2Manufacturing precision
If traditional torsion hinges require separate stamping and forming operations, then manufacturing precision can be maintained, but productivity decreases
Solution Approach 1:
The hinge leaves are pre-formed with integrated torsion bar receptacles and mounting features during the molding process itself, before final assembly. The neutral angle is also pre-set during molding, eliminating the need for subsequent forming operations and riveting steps, thus maintaining precision while significantly improving productivity.
3Strength
If traditional torsion hinges use riveting and forming operations, then structural strength is improved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces mechanical assembly operations (riveting, forming, crimping) with a molded-in integration approach. The hinge leaves are molded with built-in receptacles and attachment features that mechanically interlock with the torsion bars during molding, providing structural strength equivalent to or exceeding traditional methods while eliminating complex manufacturing operations.
4Force
If traditional torsion hinges have visible coil springs, then torsional spring torque is provided, but cosmetic appearance deteriorates
Solution Approach 1:
The torsion bars are nested within recesses or channels formed directly into the hinge leaves during molding. This nesting conceals the torsional spring elements from external view while maintaining their functional ability to provide torsional spring torque, thus achieving both cosmetic appearance and mechanical function.
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 compact, consistent, and functional torsion hinge with no free play, reducing assembly complexity and ensuring uniform torsional spring torque across products.
Implementation Method 1
formed in a single injection molding process
Implementation Method 2
torsion bar provides torsional spring torque for the hinged device
Data Source
AI summary
One aspect is an insert molded torsion bar hinge including a cylindrical metal torsion bar with a main bar body, a portion of which extends along a torsion bar axis, a first contoured bar end and a second contoured bar end on opposite ends of the main bar body. A first hinged element of molded plastic and with a first knuckle, is molded directly over and encompasses the first contoured bar end such that the first contoured bar end is fixed within and not rotatable relative to the first hinged element. The first knuckle is molded directly over and encompassing a portion of the main bar body. A second hinged element of molded plastic and with a second knuckle is molded directly over and encompasses the second contoured bar end such that the second contoured bar end is fixed within and not rotatable relative to the second hinged element. The second knuckle is molded directly over and encompassing a portion of the main bar body. The first and second hinged elements rotate and produce a torsional spring torque.