Stepped Cam Surface for Vehicle Seat Latch Noise Reduction
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Solution Overview
Problem
Conventional vehicle seat latch mechanisms produce a loud 'popping' noise due to excessive stress, which is caused by the disengagement of cams with a significant gap between the hooking mechanism and the cams, leading to unpleasant occupant experience and inability to reduce noise due to tolerances and dimensions.
Innovation Solution
A latch mechanism with a stepped surface between the cams reduces the clearance between the hooking mechanism and the cams, minimizing noise and preventing excessive movement by ensuring a tighter fit and controlled disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional latch mechanism with single cam engagement is used, then the structure is simple, but it produces loud popping noise under stress
Solution Approach 1:
The single cam engagement surface is segmented into multiple stepped engagement surfaces (first, second, third surfaces) at different heights. This segmentation allows progressive engagement of the cam with the hooking mechanism, distributing the stress across multiple contact points and preventing sudden disengagement that causes popping noise.
Solution Approach 2:
The engagement surface is extended into the vertical dimension by creating stepped surfaces at different heights. This dimensional change transforms a single-plane engagement into a multi-level engagement system, where the cam engages progressively through vertical steps, reducing the likelihood of sudden disengagement and associated noise.
2Manufacturing precision
If larger clearance is provided between hooking mechanism and cams, then assembly tolerances are easier to accommodate, but excessive movement and noise occur under stress
Solution Approach 1:
The stepped engagement surfaces are designed to progressively engage the cam with the hooking mechanism before full load is applied. This preliminary progressive engagement ensures that the components are properly seated and aligned, accommodating tolerances while preventing excessive movement under subsequent stress.
Solution Approach 2:
The engagement surface geometry is changed from a single flat surface to multiple stepped surfaces with different heights and positions. This parameter change creates a progressive engagement sequence that maintains tight clearance under load while still accommodating assembly tolerances through the stepped configuration.
3Device complexity
If single cam engagement is used, then the mechanism is simpler, but it cannot adequately handle high stress loads
Solution Approach 1:
The single cam engagement is segmented into multiple stepped engagement surfaces that distribute the stress load across different contact points. The first, second, and third engagement surfaces engage at different heights and positions, creating a progressive load distribution system that enhances overall stress load capacity.
Solution Approach 2:
Multiple engagement surfaces are merged into a single integrated cam structure. This merging combines the functionality of multiple engagement points into one component, providing enhanced stress load capacity while maintaining relative structural simplicity compared to using separate components.
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4B
AI summary
A latch for a vehicle seat may include a hooking component with a hook engagement surface, a first cam with a first cam engagement surface, and a second cam with a second cam engagement surface. The hooking component may be rotatable about a first axis and the first cam and the second cam may be rotatable about a second axis between an engaged position and an unengaged position. The hook engagement surface may contact at least one of the first cam engagement surface and the second cam engagement surface in the engaged position. One of the hook engagement surface or the first cam engagement surface may include a stepped surface extending incrementally from either the hook engagement surface or the first cam engagement surface.