Vehicle Headrest Torque Limiter for Stepless Angle Adjustment
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Solution Overview
Problem
Existing vehicle headrests are complex, costly, and lack fine adjustment capabilities, particularly in terms of forward inclination and side support, with existing mechanisms requiring multiple parts and limiting stepless adjustments.
Innovation Solution
A headrest design utilizing a coil spring type torque limiter with a stationary plate, attachment shaft, and a base plate that can be turned forward and rearward, featuring a release mechanism for coil spring tension control, allowing for stepless angular adjustments and a retracting position to avoid obstructing the driver's view when not in use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ratchet mechanism with engagement teeth is used to prevent rearward movement, then safety against rearward forces is improved, but the adjustment becomes stepwise and fine adjustments cannot be made
Solution Approach 1:
The patent changes the fundamental parameter of the torque limiting mechanism from a discrete ratchet system to a continuous coil spring system. The coil spring's torque characteristic varies continuously with rotation angle, enabling stepless fine adjustments while still providing reliable resistance to rearward forces through the spring's inherent elastic properties
2Ease of operation
If a coil spring with inner diameter smaller than shaft diameter is used, then stepless fine adjustment and simple structure are achieved, but rearward turning is restricted
Solution Approach 1:
The patent inverts the conventional approach by making the coil spring's inner diameter smaller than the shaft diameter. This inversion causes the spring to engage the shaft surface, creating friction that restricts rearward turning while allowing easy forward adjustment through the release mechanism that loosens the spring
3Reliability
If existing headrest mechanisms are used, then safety and support are provided, but the structure becomes complex and costly with many members and parts
Solution Approach 1:
The patent merges multiple functions into the single coil spring component: it provides torque limitation for safety, enables stepless adjustment, and acts as the primary mechanical element for both forward and rearward movement control. This consolidation eliminates the need for separate ratchet mechanisms, engagement teeth, and multiple locking components found in conventional designs
Solution Approach 2:
The coil spring serves itself by using its own elastic deformation and friction characteristics to provide both the adjustment mechanism and the safety function. The spring's natural properties enable it to restrict rearward movement while allowing easy forward adjustment, eliminating the need for additional safety mechanisms or complex control systems
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 provides fine, adjustable support for passengers with reduced parts and cost, ensuring safety against rearward forces while allowing easy forward adjustments and preventing neck fatigue, with enhanced safety during collisions or emergency braking.
Implementation Method 1
a coil spring wound about the attachment shaft, two ends of the coil spring being, respectively, a fixed end and a free end and an inner diameter of the coil spring being smaller than an outer diameter of the attachment shaft
Implementation Method 2
if the shaft or the coil spring is turned in a direction in which the coil spring tightens, the coil spring tightens down on the shaft and turning is restricted (or movement is very heavy), whereas, if, on the other hand, the shaft or coil spring is turned in the opposite direction, then the coil spring will turn freely (or very lightly), sliding over the shaft
Data Source
AI summary
A headrest for vehicles including a stationary plate secured to the seat back of a vehicle; an attachment shaft supported by the stationary plate; a coil spring wound on the attachment shaft and having a fixed end and a free end with its inner diameter being smaller than the outer diameter of the attachment shaft; and a headrest base plate attached to the stationary plate so as to turn forward and rearward. The fixed end of the coil spring is fixed to the base plate so as to secure the attachment shaft to the base plate or the fixed end of the coil is fixed to the stationary plate so as to secure the attachment shaft to the base plate, and the winding direction of the coil spring is set in a direction that tightens the spring when the base plate is turned rearward, thus restricting this rearward turning.