Vehicle Headrest Four-Bar Linkage Automatic Adjustment
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Solution Overview
Problem
Existing vehicle headrests lack the capability for automatic adjustment and locking, limiting their adaptability and user convenience.
Innovation Solution
A headrest system featuring a four-bar linkage with adjustable links and a drive unit, allowing for precise movement and locking of the headpiece between positions, utilizing a slotted link mechanism and a spindle nut system for efficient and space-saving adjustment, driven by a motor or other suitable drive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a four-bar linkage mechanism is used for headrest adjustment, then the adjustment precision and position definition are improved, but the device complexity increases
Solution Approach 1:
The patent employs a four-bar linkage mechanism that transforms the rotational movement of a single drive unit into precise linear adjustment of the headrest. The dynamic interaction between the crank, connecting rod, and slider ensures controlled movement along a defined trajectory, achieving precise position definition through mechanical dynamics rather than complex control systems
Solution Approach 2:
The four-bar linkage acts as an intermediary mechanism between the simple rotary drive and the headrest adjustment. This intermediate mechanical system translates simple rotational input into precise linear output movement, resolving the contradiction by using a well-defined mechanical mediator rather than complex control electronics
2Volume of moving object
If an adjusting element movable in slotted links is used, then the space requirement is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The adjusting mechanism is segmented into discrete components: slotted links with precisely defined slots, an adjusting element (slider), and a drive unit. This segmentation allows each component to be manufactured and assembled separately, with the slotted links providing precise geometric constraints that guide the adjusting element's movement, reducing overall space while maintaining precision through modular design
Solution Approach 2:
The patent changes the geometric parameters of the slotted links and adjusting element to optimize the balance between compactness and precision. By carefully designing the slot geometry, length, and orientation, the mechanism achieves accurate headrest positioning within a minimized volume, transforming the trade-off through parameter optimization
3Ease of operation
If automatic adjustment with drive unit is implemented, then the ease of operation is improved, but the device complexity and weight increase
Solution Approach 1:
The patent replaces complex electronic control systems with a purely mechanical four-bar linkage driven by a simple rotary actuator. The mechanical advantage provided by the linkage system allows a small torque from the drive unit to control the headrest adjustment, achieving automatic operation without requiring complex motors or control electronics
Solution Approach 2:
The four-bar linkage mechanism serves multiple functions simultaneously: it provides automatic adjustment through the drive unit, defines precise positioning through its geometric constraints, and enables locking in intermediate positions through the adjustable connecting rod. This multi-functionality reduces the need for separate systems, thereby reducing overall complexity while maintaining ease of operation
Data Source
AI summary
A headrest has a base carrying the headrest on a seat, a head piece forming an abutment for a head, and a four-bar linkage including a first link and at least one second link therebehind in a direction of displacement. Each link is secured at one pivot with the base and at another pivot with the head piece such that the head piece is movable by the four-bar linkage relative to the base between a first end position and a second end position. An adjuster can alter and/or arrest the relative position between one of the links and the head piece, or between one of the links and the base. This adjuster has a first slotted link fixed on one of the first and second links, a second slotted link fixed on the head piece or the base, and a slide block engaged in slots of the first and second slotted links.