Cam Hinge Assembly With Surface Contact for Uniform Wear
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Solution Overview
Problem
Existing hinge assemblies in portable electronic devices, such as notebook computers, 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 with a first and second flat surface and a curved surface, allowing surface contact between the curved surfaces during rotation, which promotes uniform wear and stable opening and closing forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a concave cam or cam on the rotating shaft is used 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 transitions from point contact to line contact by extending the contact area along the axial direction of the rotating shaft. The cam surface is designed with a specific profile that creates a line contact zone rather than a single point, effectively adding a dimensional aspect to the contact interface. This dimensional change distributes the contact stress along the axial direction, reducing wear at any single point while maintaining the torque control function.
Solution Approach 2:
The cam surface is designed with curved profiles that create a line contact geometry. The specific curvature of the cam surface works with the corresponding cam follower to establish a line contact zone. This curved geometry allows the contact area to be extended along the axial direction, transforming point contact into line contact and thereby improving wear distribution and reliability.
2Power
If a pair of cams with climbing surfaces fitted to each other is used, then torque can be generated, but the climbing surfaces still experience single-point wearing when scrutinized from multiple cross-sections
Solution Approach 1:
The patent extends the contact area from a single point to a line by utilizing the axial dimension. The cam surfaces are designed with profiles that maintain contact along a line parallel to the rotating shaft axis. This dimensional extension ensures that when viewed from multiple cross-sections, the contact is distributed along the axial direction rather than concentrated at a single point, achieving uniform wear across all cross-sections.
Solution Approach 2:
The cam surface is effectively segmented along the axial direction, creating multiple contact zones distributed along the shaft axis. Each cross-section of the cam has its own contact point, but collectively these form a continuous line contact. This segmentation approach distributes the wear across multiple locations along the axial direction, preventing single-point wear while maintaining torque generation capability.
3Device complexity
If single-point contact is used between cams, then the structure can be simple, but the opening and closing angle cannot be stable due to fast and uneven wearing
Solution Approach 1:
The patent extends the contact interface from a point to a line by utilizing the axial dimension of the rotating shaft. This line contact geometry, achieved through specific cam surface profiling, distributes the mechanical interaction along the axial direction. The result is that wear is spread out rather than concentrated, maintaining stable cam geometry and thus stable opening and closing angles over time, 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 ensures slow and uniform wear of the cams, achieving stable opening and closing angles and forces by maintaining surface contact between the curved surfaces, thereby enhancing the durability and functionality of the hinge assembly.
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
Implementation Method 2
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
AI summary
A hinge assembly, including a rotating shaft and a pair of cams, is provided. The cams are sleeved on the rotating shaft so as to be rotatable relative to each other. The pair of cams respectively has a first flat surface and a second flat surface facing each other, and a curved surface adjacent to the first flat surface and the second flat surface. The first flat surface of one of the cams passes by the curved surface to move from one flat surface to the other flat surface of the other cam, so as to enable the pair of cams to move relatively away or closer along an axial direction of the rotating shaft. The curved surfaces of the cams are in surface contact when the first flat surface passes by the curved surface. A portable electronic device is also provided.