Reclining Device Gear Surface Profile for Consistent Operation Force
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Reclining devices with external and internal teeth gears experience increased operation force and variability due to surface roughness, causing deviations in the revolution orbit and inconsistent engagement points between teeth.
Innovation Solution
Designing the external and internal teeth gears with specific surface profiles where one plane is flat and the other is convex, reducing the distance between engagement surfaces and minimizing the impact of surface roughness, resulting in a more stable and consistent operation force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If both external teeth and internal teeth are designed with involute profiles (convex and concave planes), then the gears can engage smoothly, but the surface roughness causes bumps that increase operation force and cause deviation in revolution orbit
Solution Approach 1:
The patent applies different surface profiles to different gears: one gear has a flat tooth plane while the other has a convex tooth plane. This local differentiation eliminates the bump problem caused by two convex surfaces meeting, thereby reducing operation force and preventing revolution orbit deviation while maintaining smooth engagement.
Solution Approach 2:
The invention introduces asymmetry in the tooth profile design where one tooth surface is flat and the other is convex, rather than using symmetric involute profiles on both sides. This asymmetric configuration ensures that the flat surface contacts the convex surface without creating bumps, thus reducing operation force and maintaining consistent revolution orbit.
2Manufacturing precision
If surface roughness is reduced to minimize engagement variability, then engagement points become more consistent, but manufacturing complexity and cost increase
Solution Approach 1:
Instead of requiring high precision across the entire tooth surface, the patent applies a flat profile to one tooth surface and a convex profile to the other. This local quality differentiation ensures that engagement consistency is achieved through the geometric relationship between flat and convex surfaces rather than through high manufacturing precision, thereby reducing manufacturing complexity.
Solution Approach 2:
The invention changes the geometric parameters of the tooth profiles from both convex (involute) to one flat and one convex. This parameter change fundamentally alters the engagement mechanism, making the system less sensitive to surface roughness and manufacturing variations, thus achieving consistent engagement points without increased manufacturing precision requirements.
Data Source
AI summary
The present invention relates to a reclining device that includes an external teeth gear and an internal teeth gear and in which the rotation axis of one of the external teeth gear and the internal teeth gear revolves around the rotation axis of the other. The present invention aims to provide a reclining device of which the operation force is small and the operation force varies little. To achieve the aim, one of (a) the plane of each of the external teeth 31b that engages with the internal teeth 32b and (b) the plane of each of the internal teeth 32b that engages with the external teeth 31b is arranged to be flat, and the other of (a) and (b) is arranged to be convex.