Coaxial Contra-Rotating Hinge Mechanism Without Gear Backlash
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Solution Overview
Problem
Existing foldable mobile terminals with flexible screens face issues such as tooth gaps in gear engagement structures and the need for dual-axis configurations, which increase complexity, quality risks, and costs.
Innovation Solution
A coaxial contra-rotating connecting mechanism with a cam assembly and elastic component, allowing uniaxial contra-rotation, and a four-bar mechanism with guide arc slide rails and sheet metal parts to provide synchronous rotation without gaps, using a simple folding structure that adapts to flexible screen bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gear meshing structure is used for synchronous rotation, then the contra-rotating function is achieved, but tooth gap problems occur and dual-axis configuration is required
Solution Approach 1:
The patent extracts and eliminates the gear meshing structure from the synchronous rotation mechanism. Instead of using gears with teeth that create gaps, the invention uses a cam assembly with cam surfaces that directly engage with connecting parts, removing the problematic gear teeth entirely while maintaining the synchronous contra-rotating function through a simplified uniaxial configuration
Solution Approach 2:
The patent replaces the traditional gear meshing mechanical system with a cam-based mechanical system. The cam assembly with its specially shaped cam surfaces substitutes for the gear teeth engagement, providing smooth continuous contact without gaps and achieving synchronous rotation through the geometric properties of the cam profiles rather than through gear tooth interlocking
2Reliability
If an avoidance rotation structure is added to adapt to flexible screen folding, then the flexible screen protection is improved, but the structure becomes more complex and quality risks increase
Solution Approach 1:
The patent merges the avoidance rotation function directly into the basic hinge structure. The connecting arms are designed with specific geometric shapes that inherently provide the avoidance rotation capability needed for flexible screen protection, eliminating the need for separate avoidance rotation mechanisms and simplifying the overall hinge structure
Solution Approach 2:
The patent employs curved cam surfaces and arc-shaped guide rails in the hinge mechanism. These curved geometric elements enable smooth rotational motion that naturally adapts to the folding movements of the flexible screen, providing protection through the geometric properties of the components rather than through complex mechanical additions
3Device complexity
If a cam assembly with sliding motion is used, then uniaxial contra-rotation is achieved and tooth gap problems are avoided, but positioning precision must be maintained
Solution Approach 1:
The patent introduces elastic components as intermediaries between the cam assembly and the connecting parts. These elastic elements provide continuous contact and force, ensuring that the cam surfaces remain firmly engaged with the connecting parts throughout the rotation cycle, which maintains positioning precision while accommodating minor manufacturing variations
Solution Approach 2:
The patent employs threaded locking structures that allow for adjustment of positioning parameters. By enabling fine-tuning of the cam assembly position and orientation, the system can compensate for manufacturing tolerances and achieve the required positioning precision through parameter adjustment rather than relying solely on high-precision 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 mechanism achieves high synchronous stability, reduces space requirements, improves structural strength, and lowers costs while ensuring smooth operation and precise positioning, suitable for devices like notebook computers and tablets.
Implementation Method 1
The coaxial contra-rotating connecting mechanism is further provided with an elastic component and/or a threaded locking structure to compress the first connecting part, the cam assembly and the second connecting part
Implementation Method 2
a cam assembly which can slide rather than rotating relative to the connecting shaft is provided on the connecting shaft
Implementation Method 3
the first connecting part and the second connecting part match the cam assembly at two ends of the am assembly so that the first connecting part and the second connecting part are positioned in the axial direction
Data Source
AI summary
A coaxial contra-rotating connecting mechanism includes a left rotating connecting arm, a right rotating connecting arm, and a connecting shaft. The left rotating connecting arm and the right rotating connecting arm are respectively provided with a first connecting part and a second connecting part which are sleeved on the connecting shaft and are rotatably connected to the connecting shaft; a cam assembly which can slide rather than rotating relative to the connecting shaft is provided on the connecting shaft; the cam assembly is located between the first connecting part and the second connecting part; and the first connecting part and the second connecting part are respectively provided with structures matching the cam assembly, so that the left rotating connecting arm and the right rotating connecting arm synchronously rotate in opposite directions.