Forward Adjustable Ratchet Headrest Mechanism
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Solution Overview
Problem
Existing vehicle headrests lack a reliable mechanism for controlled, multi-position manual adjustment that allows for precise positioning and easy return to the initial design position, often requiring complex mechanisms or limited incremental adjustments.
Innovation Solution
A multi-position manually adjustable headrest featuring a ratchet defined support bracket with a pivotally secured, three-dimensional intermediate component and a biased locking pawl that engages selected ratchet locations, allowing for controlled incremental adjustments and automatic return to the initial position through a combination of arcuate channels, upwardly ramped ratchet portions, and a biasing clock spring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a ratchet mechanism with locking pawl is used for headrest adjustment, then controlled incremental positioning is achieved, but the mechanism complexity increases
Solution Approach 1:
The headrest adjustment mechanism is divided into discrete incremental positions using a ratchet wheel with multiple teeth. Each tooth represents a distinct positioning stop, allowing the headrest to be adjusted to specific predetermined positions rather than continuous adjustment. This segmentation provides precise controlled positioning while keeping the mechanism relatively simple.
Solution Approach 2:
A locking pawl acts as an intermediary component that engages with the ratchet teeth to maintain the headrest at selected positions. The pawl translates the rotational movement of the intermediate component into discrete positional stops by engaging with individual ratchet teeth, providing controlled incremental positioning without requiring complex braking or friction mechanisms.
2Ease of operation
If a manual adjustment mechanism is used for headrest repositioning, then ease of operation is improved, but the control precision deteriorates
Solution Approach 1:
The mechanism allows dynamic manual adjustment in the forward direction through rotation of the intermediate component, which drives the locking pawl along the ratchet teeth. The system transitions from a static locked position to a dynamic adjustment state, then settles into a new static locked position. This dynamic operation enables easy manual repositioning while maintaining precise positioning control through the ratchet-pawl engagement.
Solution Approach 2:
The locking pawl automatically engages with the next ratchet tooth as the intermediate component rotates during manual adjustment, providing self-locking at each incremental position without requiring user intervention to lock or unlock. The biasing spring ensures the pawl remains engaged with the ratchet teeth, automatically maintaining positioning control throughout the adjustment range.
3Adaptability or versatility
If a reset mechanism is added to return headrest to initial position, then adaptability is improved, but the device complexity increases
Solution Approach 1:
The reset mechanism works by reversing the normal adjustment direction. Rotating the intermediate component in the opposite direction causes the locking pawl to disengage from the ratchet teeth and follow the downwardly inclined reset surface back to the initial position. This inversion of the engagement mechanism provides automatic resetting capability without adding separate actuators or complex control systems.
Solution Approach 2:
The downwardly inclined reset surface, which could be seen as a passive feature, is converted into an active reset mechanism. As the intermediate component rotates backward, gravity and the biasing spring work together with the inclined surface to automatically guide the locking pawl back to the initial engagement position, transforming a potential limitation into a beneficial automatic reset function.
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
Enables precise, controlled incremental adjustments between multiple positions and effortless return to the initial design position, enhancing user convenience and durability by guiding pin-supported rivets along arcuate channels and utilizing a locking pawl mechanism that engages and disengages with the ratchet portions.
Implementation Method 1
A biasing clock spring is further supported about a pin support and includes a first end abutting an edge of the support bracket and a second end biasing against a lower rim edge location of the three dimensional component.
Data Source
AI summary
A multi-position and manually adjustable headrest having a support bracket affixed atop a seat back and exhibiting a plurality of ratchet defined portions. An intermediate and three dimensional shaped component is pivotally secured in a biased fashion to the ratchet defined bracket, the intermediate component exhibiting a pivotally supported and biased locking pawl which, depending upon a pivotal location of the intermediate component, engages a selected ratchet portion of said support bracket. A pair of headrest bun supporting plates are pivotally secured at upper ends to spaced apart sides of the intermediate pivotal component, the supporting plates further exhibiting lower arcuate extending channels through which seats pin supports projecting laterally from opposite sides of the ratchet support bracket and travel along the channels during forward displacement of the bun supporting plates, such as resulting from a manual readjustment force applied to a headrest bun. Concurrent rotation of the intermediate component in a controlled fashion occurring relative to its upper pivotal connection to the support plates and lower pivotal connection to the ratchet support bracket such that the pivotally supported locking pawl engages a selected ratchet portion of the support bracket between an initial position and at least one succeeding forward adjustment position.