Helical Synchronization Gear Layout for Stable Foldable Hinges
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional foldable electronic devices with spur tooth synchronization gears suffer from poor transmission stability, leading to instability and potential gear breakage.
Innovation Solution
The rotating mechanism employs helical gears with increased contact ratios and opposite helical directions to enhance transmission stability, and incorporates a damping member for improved rotation stability and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spur tooth synchronization gears are used, then the structure is simple, but the transmission stability is poor
Solution Approach 1:
The patent changes the fundamental parameter of gear tooth geometry from spur teeth to helical teeth. This parameter change transforms the engagement mode from line contact to gradual contact along the helix angle, significantly improving transmission stability and reducing impact loads while maintaining structural feasibility
Solution Approach 2:
The synchronization gear employs a composite structure combining multiple helical gears (first helical gear, second helical gear, and intermediate helical gear) with opposite helical directions. This composite gear system achieves superior transmission stability by distributing loads across multiple engagement points and canceling axial forces through the opposite helix configuration
2Strength
If conventional synchronization gears are used, then the manufacturing is simple, but gear breakage risk is high
Solution Approach 1:
The helical tooth geometry parameter change increases the contact ratio and distributes mechanical stresses more evenly across the tooth surface. This reduces peak stresses at the tooth root, preventing fatigue failure and breakage while enhancing overall gear strength and durability
Solution Approach 2:
The intermediate helical gear acts as a mediator between the first and second helical gears, providing additional support and load distribution. This intermediate element reduces the burden on each individual gear, decreasing the risk of breakage through shared stress distribution
3Reliability
If helical gears with opposite helical directions are used, then transmission stability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs asymmetric helical tooth configurations with opposite helical directions on different gears. This asymmetric design, while requiring precise manufacturing, creates self-balancing axial forces that cancel each other out, reducing the need for extremely high precision in individual gear components while maintaining overall system stability
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
This application provides a rotating mechanism and a foldable electronic device. The rotating mechanism includes a fixed base, a first synchronization swing arm, a second synchronization swing arm, and a synchronization gear. A first gear, an intermediate gear, and a second gear of the synchronization gear are all helical gears, the first gear, the intermediate gear, and the second gear are disposed side by side and in parallel, and the intermediate gear is located between the first gear and the second gear and engages with the first gear and the second gear. The first synchronization swing arm is fastened to the first gear, and the second synchronization swing arm is fastened to the second gear. The synchronization gear is mounted in the fixed base and is rotatably connected to the fixed base, the first synchronization swing arm and the second synchronization swing arm are respectively located on two opposite sides of the fixed base in a width direction, a rotation direction of the first synchronization swing arm is opposite to a rotation direction of the second synchronization swing arm, and a rotation direction of the first gear is opposite to a rotation direction of the second gear. The rotating mechanism provided in this application can resolve a technical problem of poor transmission stability of a rotating mechanism in the conventional technology.