Portable Device Hinge Cam Assembly for Uniform Wear Control
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Solution Overview
Problem
Existing hinge assemblies in portable electronic devices suffer from unstable and uneven wear due to single-point contact between cams, leading to inconsistent opening and closing angles and forces.
Innovation Solution
A hinge assembly design featuring a rotating shaft with a pair of cams, each having flat surfaces and curved surfaces that maintain surface contact during rotation, ensuring uniform wear and stable opening and closing forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a concave cam or cam is used on the rotating shaft to generate different torques by different stroke positions, then the opening and closing force can be controlled, but the wearing situation becomes unstable due to single-point contact
Solution Approach 1:
The patent applies curvature by designing the climbing surface of the cam as an arc-shaped curved surface rather than a flat or concave surface. This curved surface ensures that the contact point between the cam and the cam follower traces an arc path, transforming single-point contact into continuous surface contact along the arc, thereby distributing wear uniformly and improving reliability while maintaining torque control functionality
2Reliability
If a pair of cams with fitted climbing surfaces is used, then the design intends to even out the wearing, but gaps are found between the climbing surfaces when dissected into multiple cross-sections, causing single-point wearing
Solution Approach 1:
The patent resolves the fitting precision issue by designing the climbing surface as a three-dimensional arc-shaped curved surface that maintains continuous surface contact when the cam rotates. The arc geometry ensures that at any cross-sectional view, the contact occurs along a curved path rather than at discrete points or with gaps, achieving uniform wear distribution without requiring extremely tight manufacturing tolerances for surface fitting
3Device complexity
If single-point contact is used between the cam and cam follower, then the structure is simple, but the wearing is fast and uneven, unable to achieve stable opening and closing angle and force
Solution Approach 1:
The patent maintains relatively simple cam structure while improving reliability by curving the climbing surface into an arc shape. This curved surface design transforms the contact mechanism from single-point to continuous surface contact along the arc path, distributing the mechanical stress and wear across a larger area, thereby achieving stable opening and closing angles and forces without significantly increasing structural complexity
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 design achieves slow and uniform wear between the cams, resulting in stable opening and closing angles and forces, enhancing the durability and functionality of portable electronic devices.
Implementation Method 1
The curved surfaces of the pair of cams are in surface contact when the first flat surface passes by the curved surface... enabling their wearing to be slow and uniformed
Data Source
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AI summary
A hinge assembly (200), including a rotating shaft (22) and a pair of cams (25, 26), is provided. The cams (25, 26) are sleeved on the rotating shaft (22) so as to be rotatable relative to each other. The pair of cams (25, 26) respectively has a first flat surface (251, 253, 261, 263) and a second flat surface (252, 254, 262, 264) facing each other, and a curved surface (C1, C2, C3, C4, C5, C6, C7, C8) adjacent to the first flat surface (251, 253, 261, 263) and the second flat surface (252, 254, 262, 264). The first flat surface (251, 253, 261, 263) of one of the cams (25, 26) passes by the curved surface (C1, C2, C3, C4, C5, C6, C7, C8) to move from one flat surface to the other flat surface of the other cam (25, 26), so as to enable the pair of cams (25, 26) to move relatively away or closer along an axial direction of the rotating shaft (22). The curved surfaces (C1, C2, C3, C4, C5, C6, C7, C8) of the cams (25, 26) are in surface contact when the first flat surface (251, 253, 261, 263) passes by the curved surface (C1, C2, C3, C4, C5, C6, C7, C8). A portable electronic device (100) is also provided.