Vehicle Headrest Adjustment Kinematics for Low-Play Positioning
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Solution Overview
Problem
Existing headrest adjustment devices in vehicles suffer from play, leading to reduced accuracy and comfort, as well as potential rattling noises and increased space usage, due to their mechanism design.
Innovation Solution
A headrest adjustment device featuring a drive element coupled to adjusting parts via meshing drive contours with twist adjustment paths, allowing for relative movement between parts, reducing play, and incorporating a motor-driven scissor kinematics for precise adjustment and modular design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional adjustment device mechanism is used, then the headrest can be adjusted, but play occurs leading to reduced accuracy and comfort
Solution Approach 1:
The patent employs a scissor kinematics mechanism with four adjusting parts that dynamically adjust the headrest position. The mechanism uses rotating adjusting parts with drive contours that engage with a drive element, enabling smooth positional changes without play. The dynamic rotation and engagement of meshing contours maintain continuous contact between components, eliminating gaps and ensuring precise adjustment throughout the range of motion.
2Object-affected harmful factors
If a conventional adjustment device mechanism is used, then the headrest can be adjusted, but rattling noises occur reducing comfort
Solution Approach 1:
The scissor kinematics mechanism ensures continuous engagement of drive contours between the drive element and adjusting parts throughout the adjustment range. This dynamic meshing connection eliminates gaps and loose contacts that cause rattling noises. The rotating adjusting parts maintain constant contact with the drive element, ensuring smooth operation without vibration or noise during headrest adjustment.
Solution Approach 2:
The adjustment device is divided into four separate adjusting parts (first, second, third, and fourth adjusting parts) that form a scissor-like structure. Each adjusting part has its own drive contours that engage with the drive element, distributing the adjustment function across multiple segments. This segmentation allows each component to be precisely engineered for smooth operation while the collective arrangement provides stable, noise-free adjustment.
3Reliability
If a spindle drive with spindle oriented in displacement direction is used, then adjustment can be achieved, but the housing must be highly secure increasing complexity
Solution Approach 1:
Instead of orienting the drive element (spindle) in the displacement direction as in conventional designs, this patent inverts the approach by using a drive element that rotates perpendicular to the displacement direction. The scissor kinematics mechanism converts this rotational motion into linear adjustment of the headrest, eliminating the need for a highly secure housing around a longitudinal spindle while maintaining crash safety and adjustment functionality.
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 solution provides improved adjustability, reduced play, and minimized noise, while optimizing the design for compactness and weight reduction, enhancing user comfort and operational efficiency.
Implementation Method 1
the drive element is coupled to each of the adjusting parts via meshing drive contours (the drive contours engage one another)
Implementation Method 2
incorporating a motor-driven scissor kinematics for precise adjustment
Data Source
AI summary
A headrest for a vehicle seat, comprises an adjustment device comprising at least two adjusting parts and a drive element movable along an axis, wherein the drive element is coupled to the adjusting parts via engaging drive contours which are defined for each of the adjusting parts describe at least one adjustment path, the adjustment path of at least one of the adjusting parts having a twist with respect to the axis and extending from the adjustment path of at least one other of the adjusting parts so that an axial movement of the driving member along the axis causes a relative rotation between the adjusting parts.