Vehicle Seat Headrest Linkage for Stable Rear-Impact Protection
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Solution Overview
Problem
Existing headrests for motor vehicles lack stability in their protective position during rear impacts, which can lead to inadequate protection for passengers' heads and necks.
Innovation Solution
The headrest incorporates a third connecting rod and two resilient devices, with the second connecting rod pivotably mounted on one element and slidably mounted relative to another, to enhance stability by urging the mobile part into a protective position, utilizing helical springs and toothed sections for precise movement control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a headrest uses a mobile part that can displace towards the head of the occupant during rear impact, then protection of the passenger's head and neck is improved, but the stability of the mobile part in the protective position deteriorates
Solution Approach 1:
The patent applies local quality by making the connecting rods asymmetric in structure and function. The first connecting rod has a pivotable connection on the fixed part, while the second connecting rod has a pivotable connection on the mobile part. This asymmetric local configuration allows each rod to perform its specific function - the first rod provides stable anchoring while the second rod enables controlled displacement and stability in the protective position through its pivotable connection on the mobile part.
Solution Approach 2:
The patent introduces a third dimension of stability by adding the third connecting rod that connects the first and second connecting rods. This creates a triangular rigid structure that prevents unwanted movements of the mobile part in directions other than the intended displacement path. The third connecting rod constrains the system in the lateral dimension, ensuring the mobile part remains stable when displaced to the protective position while still allowing controlled movement along the primary axis.
2Device complexity
If the headrest uses only two connecting rods, then the structure remains simple, but the stability and control of the mobile part in protective position deteriorates
Solution Approach 1:
The patent segments the connecting mechanism into three distinct connecting rods, each with specific functions. The first connecting rod connects the fixed part to the mobile part with a pivotable connection on the fixed part. The second connecting rod connects the fixed part to the mobile part with a pivotable connection on the mobile part. The third connecting rod connects the first and second connecting rods. This segmentation allows each rod to be optimized for its specific role while working together to provide overall system stability.
Solution Approach 2:
The third connecting rod adds a new dimension to the structural stability by creating a triangular configuration. This third element transforms the system from a potentially unstable two-rod arrangement into a rigid triangular structure that resists deformation. The third connecting rod provides lateral constraint and ensures that the mobile part maintains its position securely when displaced, without requiring excessive complexity in the individual rod designs.
3Reliability
If resilient devices are added to urge the mobile part towards the protective position, then the reliability of protection is improved, but the device complexity increases
Solution Approach 1:
The resilient devices are pretensioned in the normal position of the mobile part, performing preliminary action by pre-storing energy. This pretensioning ensures that when the retaining device releases the mobile part during a rear impact, the resilient devices immediately urge the mobile part towards the protective position without requiring additional activation mechanisms. The energy is already stored and ready to act, improving reliability while minimizing the need for complex control systems.
Solution Approach 2:
The resilient devices automatically perform the function of urging the mobile part towards the protective position without requiring external control or additional actuators. Once the retaining device releases the mobile part, the pretensioned resilient devices self-actuate to move the mobile part to the protective position. This self-service mechanism improves reliability by eliminating dependencies on complex control systems while keeping the device complexity relatively low.
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 improved headrest design ensures the mobile part remains stable and effectively displaces to protect the passenger's head and neck during rear impacts, preventing injuries by maintaining the protective position securely.
Implementation Method 1
first and second resilient devices acting respectively on the first and second connecting rods to urge said mobile part towards the protective position, said first and second resilient devices being pretensioned when the mobile part is in the normal position
Implementation Method 2
the first resilient device comprising at least one first helical spring mounted between said first and third connecting rods; the second resilient device comprising at least one second helical spring mounted between said second and third connecting rods
Data Source
AI summary
Headrest (150) comprising a fixed part (111), a mobile part (112) opposite the fixed part, first (114) and second (115) connecting rods, each connecting rod comprising two branches, connecting the fixed part to the mobile part and two resilient devices acting on the first and second connecting rods to distance the mobile part from the fixed part. The first and second connecting rods respectively slide on the mobile and fixed parts and a third connecting rod (113) is provided to connect the fixed and mobile parts.