Vehicle Headrest Latch Assembly for Reliable Height Unlocking
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Solution Overview
Problem
Existing motor-vehicle headrests face challenges in ensuring functional reliability and operating convenience for locking and unlocking the height position of the head contact part, particularly due to complex and unreliable latch mechanisms.
Innovation Solution
A headrest design featuring a latch mechanism with a U-shaped spring and actuation elements that allow for uniform movement of spring arms, facilitating easy engagement and disengagement with engagement notches on the support rod, ensuring reliable locking and unlocking with minimal effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex latch mechanism with multiple components is used, then the headrest height position can be locked, but the functional reliability and operating convenience deteriorate due to complexity
Solution Approach 1:
The latch mechanism is segmented into distinct functional components: a spring element with engagement protrusion, a separate actuator with release surface, and engagement notches on the support rod. This segmentation allows each component to be optimized independently while maintaining overall reliability and reducing complexity through clear functional separation.
Solution Approach 2:
The actuator is extracted as a separate movable component from the spring element. This allows the actuator to be independently controlled and moved between latching and unlatching positions, simplifying the overall mechanism by separating the locking function (spring) from the control function (actuator).
2Reliability
If a complex latch mechanism with multiple components is used, then the headrest height position can be locked, but the ease of operation worsens due to complexity
Solution Approach 1:
The spring element automatically engages with the engagement notch when the actuator is in the latching position, without requiring manual intervention. The biasing force of the spring ensures automatic locking, improving ease of operation while maintaining reliability.
Solution Approach 2:
Instead of requiring active force to maintain locking, the mechanism uses passive spring biasing to maintain the latched state. The actuator only needs to be moved to the unlatching position to release the lock, inverting the traditional approach where continuous force is needed to maintain the locked state.
3Reliability
If the spring is biased strongly toward the rod, then engagement reliability improves, but the effort required to unlatch increases
Solution Approach 1:
The actuator serves as an intermediary between the user and the spring element. It provides a release surface that allows the user to apply force to move the spring element against the biasing force, thereby reducing the direct force requirement on the user while maintaining engagement reliability through the spring's strong biasing.
Solution Approach 2:
The actuator introduces a new dimension of movement (lateral movement between latching and unlatching positions) that is perpendicular to the vertical movement of the headrest. This dimensional change allows the unlatching operation to be performed with minimal force in a different direction, reducing the effort required while maintaining strong engagement.
4Reliability
If the actuator is designed with large movement range, then engagement/disengagement reliability improves, but the device complexity increases
Solution Approach 1:
The actuator is designed as a flexible, elongate element that can bend and move laterally between latching and unlatching positions. This flexible design allows for a large movement range without requiring complex mechanical linkages, joints, or actuators, thereby maintaining simplicity while ensuring reliable engagement and disengagement.
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
The design enhances the functional reliability and ease of operation by allowing for precise control over the headrest's height adjustment, ensuring secure locking and effortless unlocking, improving overall user experience.
Implementation Method 1
a spring carried on the other of the parts has a pair of legs flanking the rod, elastically deflectable toward and away from the rod, and biased elastically toward the rod
Data Source
AI summary
A headrest assembly securable to a motor-vehicle seat back part has a movable headrest and a rod fixed in the seat back and having a plurality of vertically spaced catch formations. A spring carried on the headrest has a pair of legs flanking the rod, elastically deflectable toward and away from the rod, and biased elastically toward the rod, and a crosspiece connecting the legs and fittable with one of the catch formations. An actuator shiftable in the slide relative to the spring has respective actuating formations engageable with the spring legs. The actuator is movable between a latching position in which the actuating formations are generally disengaged from the respective legs and the crosspiece engages the rod and an unlatching position in which the actuating formations engage the respective legs and press them into the released position.