Mechanical stretching device for movable seat unit and seat unit
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Solution Overview
Problem
Existing mechanical stretching devices for movable seat units often result in the footrest mechanism rubbing the ground and having a short stretched length, leading to discomfort due to inadequate support for legs and feet in relaxing and lying states, and suffer from structural instability and noise issues with conventional chute structures.
Innovation Solution
A mechanical stretching device with a footrest extension mechanism comprising multiple connecting rods and footrest elements, allowing flexible extension and retraction, and a linkage support with a transmission structure for motor-driven operation, which adjusts the angle and height to create a 'zero gravity' position with improved comfort and support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the footrest mechanism is extended to provide longer stretch length, then leg and foot support is improved, but the mechanism may rub the ground causing noise and wear
Solution Approach 1:
The footrest mechanism transitions from a single-plane horizontal movement to a two-dimensional trajectory combining horizontal extension and vertical elevation. The linkage structure lifts the footrest upward while extending it forward, ensuring the footrest pads remain elevated above the ground throughout the stretching motion, thereby eliminating ground contact, noise, and wear while achieving extended stretch length for improved leg and foot support
2Device complexity
If conventional chute structures are used for footrest movement, then the structure is simple, but structural instability and noise occur
Solution Approach 1:
The invention replaces the conventional chute-based mechanical guidance system with a linkage mechanism that uses rotational joints and geometric constraints to guide footrest motion. This substitution eliminates the sliding contact inherent in chute structures that causes noise and wear, while providing smoother, more reliable movement through pinned connections and triangular linkage geometry that maintains structural stability throughout the range of motion
3Ease of operation
If the footrest mechanism is designed for extended reach, then comfort in lying state is improved, but structural wear increases
Solution Approach 1:
The invention replaces sliding chute mechanisms with a linkage system using rotational joints and pinned connections that eliminate continuous sliding friction. The triangular linkage geometry distributes mechanical loads across multiple members and joints, reducing stress concentration and wear on individual components. This allows the footrest to achieve extended reach for improved lying state comfort while maintaining structural durability through reduced wear and more evenly distributed mechanical stresses
Data Source
AI summary
The present disclosure relates to a mechanical stretching device for a movable seat unit, and a movable seat unit thereof. The mechanical stretching device includes: a linkage support that comprises a support structure configured to support the mechanical stretching device on ground and a linkage structure attachable to a seating portion of the seat unit; a back mechanism that is pivotally connected to the linkage support and is configured to attach to a backrest of the seat unit; and a leg stretching structure including a footrest element, and the leg stretching structure is pivotally connected to the linkage support, and the footrest element is attached to a footrest of the seat unit. The mechanical stretching device is configured to implement a sequential conversion or a reverse sequential conversion of the seat unit from a sitting state to a relaxing state and to a lying state.