Vehicle Seat Headrest Latch Geometry for Precise One-Hand Adjustment
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Solution Overview
Problem
Existing headrest designs for motor vehicle seats suffer from imprecise positioning and rotational issues when adjusting the secondary body with one hand, leading to unfavorable qualitative sensations due to non-complementary locking mechanisms and asymmetrical actuation.
Innovation Solution
The headrest design features lateral locking parts on the latch and a complementary rear end groove, ensuring precise positioning and minimal rotation during adjustment, with the latch fitting snugly into grooves and grooves having complementary shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the locking part is positioned in the middle of the latch for complementary shape fitting, then precise positioning sensation is improved, but rotation occurs during asymmetric one-handed operation
Solution Approach 1:
The latch is divided into multiple locking parts: a first locking part in the middle for precise positioning sensation, and second locking parts at the ends for rotational stability. This segmentation allows each part to fulfill its specific function without interfering with the other.
Solution Approach 2:
The operating direction is made asymmetric by providing different locking mechanisms for forward and backward movements. The inclined rear face allows easy forward movement, while the vertical front face provides blocking for backward movement, creating directional asymmetry in operation.
2Ease of operation
If the groove has inclined rear face and vertical front face for one-way sliding, then forward adjustment is simplified, but backward blocking requires voluntary unlocking
Solution Approach 1:
The locking mechanism transitions from a static complementary shape fit to a dynamic ratchet mechanism. The inclined rear face allows the latch to passively follow the rack during forward movement, while the vertical front face actively blocks backward movement, creating dynamic adaptability to movement direction.
Solution Approach 2:
The spring acts as an intermediary element that provides the blocking force for backward movement. When the user pulls the latch, the spring releases to allow backward movement; otherwise, the spring maintains the blocking position, mediating between the user's action and the locking requirement.
3Length of moving object
If the end groove has vertical faces for blocking forward movement, then stroke limitation is achieved, but positioning sensation becomes imprecise due to non-complementary shapes
Solution Approach 1:
The end groove is segmented into two functional zones: a first portion with an inclined rear face for precise positioning sensation through complementary shape fitting, and a second portion with a vertical front face for blocking forward movement. This segmentation allows both precision and stroke limitation to coexist.
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
Ensures perfect translation and favorable qualitative sensation during one-handed adjustment, with enhanced rigidity and clear separation of intermediate and end-of-stroke locking functions.
Implementation Method 1
said device further comprising a spring means for actuating said latch in locking and a means for actuating said latch in unlocking against said spring means
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
The invention relates to a headrest (1) comprising a secondary body (4) mounted to slide longitudinally on a main body (3) via a locking device comprising a latch (5) mounted to slide vertically on said main body between a locking position - unlocking position - where it cooperates with - moves away from - a rack (6) having a plurality of grooves (22) having a rear face (23) inclined and a front face (24) substantially vertical, said latch having a locking portion of a shape complementary to that of said grooves, so that said latch placed in the locked position fits snugly into the groove (22) in which it is engaged, as well as another locking portion and an additional portion (25) arranged to fit into a rear end groove (30) of the rack (6) when said secondary body is disposed at the end of its forward travel.