Reclining Hinge Pin Geometry for Stronger Biasing Member Locking
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Solution Overview
Problem
Existing reclining mechanisms require a large diameter operating shaft to secure strength, making it difficult to mount additional members due to the formation of slotted parts, which limits the design and functionality.
Innovation Solution
A reclining device with a hinge pin featuring a non-circular engagement part and no slit, allowing for reduced diameter and enhanced strength, enabling reliable locking of biasing members and easy mounting of additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a slotted part is formed in the operating shaft to lock the biasing member, then the biasing member can be secured, but the strength of the operating shaft is reduced requiring a larger diameter
Solution Approach 1:
The operating shaft is divided into two distinct parts: a circular main body that maintains structural strength, and a separate non-circular engagement part that provides the locking function. This segmentation allows each part to optimize its shape for its specific function without compromising the other.
Solution Approach 2:
Different cross-sectional shapes are applied to different parts of the operating shaft. The main body has a circular cross-section optimized for strength, while the engagement part has a non-circular cross-section optimized for locking the biasing member. This local differentiation resolves the contradiction between strength and locking reliability.
2Strength
If the diameter of the operating shaft is increased to secure strength, then the strength is improved, but the device size is enlarged and mounting other members becomes difficult
Solution Approach 1:
By separating the strength-critical main body from the function-specific engagement part, the design allows a smaller overall diameter while maintaining both strength and the ability to mount additional members on the non-circular engagement part.
Solution Approach 2:
The non-circular cross-section of the engagement part provides flat surfaces and geometric features that facilitate mounting of additional members, while the circular main body maintains strength. This asymmetric design enables both strength and adaptability.
3Reliability
If a slotted part is formed in the operating shaft, then the biasing member can be locked, but it becomes difficult to mount another member on the end of the operating shaft
Solution Approach 1:
The operating shaft is segmented into a circular main body and a separate non-circular engagement part. This segmentation allows the engagement part to provide locking functionality while preserving the end of the main body for mounting additional members, resolving the contradiction between locking reliability and adaptability.
Solution Approach 2:
The non-circular cross-section is applied locally to the engagement part where locking is needed, while the main body maintains its circular shape for strength and mounting purposes. This localized application of different geometries resolves the contradiction.
Data Source
AI summary
A reclining device includes: a reclining mechanism, which is capable of tilting of a seat back relative to a seat cushion to be locked or unlocked; a hinge pin, which is engaged with the reclining mechanism and configured to cause the reclining mechanism to be in an unlocked state; a first biasing member, one end of which is hooked to a hooking part provided at a seat-cushion-side member; and a second biasing member, one end of which is engaged to a periphery of an engagement part formed at the hinge pin and the other end of which is hooked to the seat-cushion-side member, wherein a vertical cross-section of the engagement part of the hinge pin has a non-circular shape.