Foldable Hinge Cam Assembly for Auto-Opening With Stable Damping
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Solution Overview
Problem
Conventional rotary shaft assemblies in foldable electronic devices are designed primarily for manual folding and unfolding, leading to difficulty in use due to varying friction forces during rotation, affecting the user experience.
Innovation Solution
A rotary shaft assembly with a connecting shaft, cam groups, and an elastic member, featuring inclined sliding surfaces that allow for automatic switching between open and closed states, ensuring consistent damping force and ease of use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If an uneven concave-convex structure is designed on the contact surface of two cams to provide damping force during manual folding, then damping force is provided, but friction force varies with rotation angle making the assembly difficult to use
Solution Approach 1:
The patent introduces a dynamic adjustment mechanism where the contact surface between the two cams is made adjustable rather than fixed. The second cam can rotate relative to the first cam around the connecting shaft axis, allowing the contact surface to dynamically adapt to different rotation angles. This dynamic adjustment ensures that the damping force remains consistent throughout the folding process, eliminating the varying friction force problem of conventional fixed uneven structures.
Solution Approach 2:
The patent changes the parameter of the contact surface orientation by allowing the second cam to rotate. This parameter change enables the contact surface to maintain an optimal orientation relative to the direction of motion at different rotation angles, ensuring consistent damping force and friction force throughout the folding range, thereby improving ease of use.
2Force
If axial pressure is applied to cause the two cams to extrude each other for damping, then damping effect is achieved, but the structure becomes complex and difficult to control
Solution Approach 1:
The patent uses the elastic recovery force of the bent plate as a natural, self-regulating mechanism. The bent plate is pre-bent to store elastic energy, and as the cams rotate, this elastic force automatically provides the necessary axial pressure for damping without requiring additional complex pressure application mechanisms. This approach simplifies the structure while maintaining effective damping control.
Solution Approach 2:
The bent plate structure serves itself by using its own elastic recovery force to provide the damping pressure. The system does not require external control mechanisms or additional components to apply axial pressure; the elastic deformation and recovery of the bent plate automatically generates the necessary force, reducing 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 assembly enables automatic switching from a closed to an open state, enhancing convenience and reducing effort required during use, while maintaining stability and control over the rotation process.
Implementation Method 1
an elastic member, configured to apply elastic force to the first cam through deformation of the elastic member, so that the first cam and the second cam are in mutual contact and extrusion
Implementation Method 2
surfaces on which the two cams are in contact are in mutual friction... each of the at least one protruding part always slides on the sliding surface of a corresponding recessed part
Data Source
Figure 1~2b
Figure 3a
Figure 3b~5
AI summary
This application provides a rotary shaft assembly, a hinge apparatus, and a foldable electronic device. A cam group of the rotary shaft assembly includes a first cam and a second cam, and the first cam and the second cam are in mutual contact and extrusion, and can rotate relative to each other. A protruding part is disposed on the first cam, a recessed part is disposed on the second cam, and the recessed part has a sliding surface. When the first cam rotates relative to the second cam, the protruding part always slides on the sliding surface of a corresponding recessed part. The sliding surface is inclined relative to a plane perpendicular to an axis of a connecting shaft, and extends, from a first end to a second end, toward a direction away from the first cam in a direction of the axis of the connecting shaft. When the foldable electronic device is in a closed state, the protruding part abuts against the first end of the corresponding sliding surface. When the foldable electronic device is in an open state, each protruding part abuts against the second end of the corresponding sliding surface. The rotary shaft assembly provided in this application can rotate automatically, so that the foldable electronic device can automatically pup up from the closed state to the open state, which makes it more convenient and effort-saving.