Folding Headrest Mechanism with Torsion Spring and Cam Lock
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Solution Overview
Problem
Existing folding headrests for automobile passenger seats lack an efficient mechanism for easy folding and locking, often requiring significant force and not allowing for sufficient reduction in height to prevent contact with the dashboard or driver's seat during folding.
Innovation Solution
A folding headrest mechanism supported by a mounting rod bar beam, utilizing a preloaded torsion spring, a cam with a notch, and a locking lever with a tooth, along with a pushrod and L-shaped lever, allows for easy folding and locking by overcoming restorative forces with a user-applied normal force, reducing the headrest's height and preventing forward rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional folding mechanism is used, then the headrest can be folded, but it requires significant force and is difficult to operate
Solution Approach 1:
The patent introduces a pushrod as an intermediary component between the button and the locking lever. When the button is pressed, it activates the pushrod which then transmits force to the locking lever, causing it to pivot and disengage from the cam's notch. This intermediary mechanism amplifies the user's input force and directs it efficiently to unlock the headrest, resolving the contradiction between ease of operation and force required.
Solution Approach 2:
The first torsion spring provides self-service by automatically returning the locking lever to its locked position with the cam's notch after folding operation, and by preloading the housing for rotation. This eliminates the need for additional actuators or complex control systems, making the mechanism self-regulating and easy to operate while minimizing the force user needs to apply.
2Length of moving object
If the headrest is folded completely, then the height is reduced to prevent contact with dashboard, but the locking mechanism may not engage properly
Solution Approach 1:
The cam is designed with a notch that is positioned and shaped to engage with the locking lever's tooth at the precise moment when the headrest reaches its fully folded position. The second torsion spring pre-positions the locking lever so that when the headrest folds, the tooth naturally aligns with and engages the notch without requiring additional adjustment or force, ensuring reliable locking at the correct height position.
Solution Approach 2:
The patent replaces complex mechanical linkages with a cam-and-follower mechanism. The cam's notched profile directly controls the locking lever's position through its rotation, substituting for traditional multi-component locking systems. This simplified mechanism ensures that the locking action is inherently tied to the folding motion, guaranteeing reliable engagement when the headrest reaches its folded position.
3Device complexity
If a simple folding mechanism is used, then the device complexity is low, but it does not provide sufficient height reduction
Solution Approach 1:
The patent utilizes rotational motion in a different dimension - the headrest rotates horizontally around a shaft rather than simply folding linearly. The cam mechanism converts this rotational motion into the vertical height reduction needed. This dimensional approach allows for significant height reduction while maintaining a relatively simple mechanism structure, as the cam's profile directly controls the folding angle and final position.
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
Enables easy and efficient folding of the headrest, reducing the risk of contact with the dashboard or driver's seat, while allowing for rapid folding and secure locking in the upright position, enhancing user convenience and safety.
Implementation Method 1
the housing is preloaded for rotation with respect to the shaft by a first torsion spring
Implementation Method 2
a coil spring between the housing and the locking lever resiliently biases the locking lever toward the cam
Data Source
AI summary
A folding headrest is disclosed, supported by a mounting rod bar beam, comprising a headrest shell connected to a housing, wherein the housing is pivotably supported on a shaft fixed to the mounting rod, wherein the housing is preloaded for rotation with respect to the shaft by a first torsion spring, an actuating button connected to in sliding communication with the headrest shell, the button in contact with a pushrod, wherein the pushrod passes within into the housing, a force direction-changing L-shaped lever pivot arm pivotably connected to pivotably disposed on the housing, wherein the longitudinal axis of the pushrod is substantially orthogonal to a plane containing the axis of rotation of the force direction-changing lever, a locking lever pivotably connected to pivotably disposed on the housing.