Auto-Return Headrest Mechanism for Fold-Forward Seat Backs
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Solution Overview
Problem
Existing seat assemblies do not efficiently automate the movement of headrests between upright and folded positions in response to the pivoting of the seat back, leading to user inconvenience and potential safety hazards.
Innovation Solution
A seat assembly with a pivotally attached headrest and integrated actuator mechanism that automatically adjusts the headrest to an upright position when the seat back is returned to an in-use position, utilizing a cam and pawl system to tension cables for smooth operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a pivoting headrest mechanism is added to allow folding, then headrest adaptability is improved, but device complexity increases due to additional mechanisms required for both folding and returning
Solution Approach 1:
The patent combines the folding mechanism and return mechanism into a single integrated system. The cam-pawl mechanism serves dual functions: the cam converts seat back movement into headrest folding motion, while the same cam-pawl assembly automatically returns the headrest to upright position when the seat back is returned. This merging eliminates the need for separate mechanisms for folding and returning, reducing overall device complexity while maintaining adaptability.
Solution Approach 2:
The cam component performs multiple functions within the mechanism. It acts as both the actuator for forward folding (converting seat back pivot motion to headrest tilt motion) and the driver for automatic return (storing and releasing energy to restore headrest position). The pawl serves as both a locking element during folding and a release element during return. This multi-functionality reduces the number of separate components needed, addressing the complexity issue.
2Device complexity
If manual adjustment is required for headrest return, then device complexity is reduced, but ease of operation deteriorates due to additional manual steps
Solution Approach 1:
The mechanism is designed to automatically return the headrest to its upright position without requiring manual intervention. The cam-pawl system self-activates when the seat back is returned to its normal position, using the stored mechanical energy to propel the headrest back. This self-service capability eliminates the need for users to manually adjust the headrest, significantly improving ease of operation while the integrated design keeps complexity manageable.
Solution Approach 2:
The mechanism performs preliminary action by automatically returning the headrest to the upright position before the user would need to use it again. When the seat back is returned to its in-use position, the cam-pawl mechanism proactively restores the headrest, ensuring it is ready for immediate use without requiring the user to take any action. This preliminary action enhances operational convenience.
3Ease of operation
If an automatic return mechanism is integrated, then ease of operation is improved, but device complexity increases due to additional components
Solution Approach 1:
The patent merges the return mechanism with the existing folding mechanism components. The cam and pawl that enable folding also drive the automatic return function. By combining these functions into a single integrated system rather than adding a separate return mechanism, the patent achieves automatic headrest return while minimizing the increase in device complexity. The cables and actuators serve dual purposes in both folding and returning operations.
4Reliability
If separate mechanisms are used for folding and returning, then reliability is improved through redundancy, but device complexity increases
Solution Approach 1:
The cam-pawl mechanism is designed as a universal system that handles both folding and returning operations with the same core components. The cam converts motion in both directions, and the pawl engages and disengages to control the headrest position during both folding and returning. This multi-functional design achieves positioning reliability for both operations without the complexity of completely separate mechanisms, as the same robust components are used for both critical functions.
Data Source
AI summary
An assembly comprises a seat bottom and a seat back pivotally attached to the seat bottom. The seat back is pivotal between a fold-forward position and an in-use position. A headrest is pivotally attached to the seat back by a tilt mechanism and is pivotal between a folded position and an upright position via the tilt mechanism. The tilt mechanism pivots the headrest forward to the folded position in response to the seat back being pivoted to the fold-forward position. A headrest-return mechanism is operably coupled to the seat back and to the headrest, wherein the headrest-return mechanism actuates the headrest such that the headrest is pivoted from the folded position to the upright position in response to the seat back being pivoted from the fold-forward position to the in-use position.