Rear-Leg Retractable Rollers for Stable Chair Mobility
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Solution Overview
Problem
In care organizations, particularly retirement homes, moving seated individuals to position them around a table is challenging due to the difficulty in sliding chairs without significant physical effort, risking tipping, and existing solutions like castors with mechanical locking are not ergonomic or aesthetically compatible with standard furniture.
Innovation Solution
A displacement device with wheels or shoes of low friction, mounted on rear wheels, that can assume a stable retracted or protruding position, featuring a pedal-operated mechanism to manage the chair's movement, ensuring stability and ease of use with automatic return to a safe position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If castors with mechanical locking are used, then the chair can be moved and immobilized, but the device complexity increases and aesthetics are compromised
Solution Approach 1:
The patent extracts the locking mechanism from a complex mechanical system and replaces it with a simple foot-operated pedal that tilts the chair to engage or disengage castors. This simplifies the device while maintaining the ability to move and immobilize the chair.
Solution Approach 2:
The chair automatically engages or disengages castors based on its tilt position, eliminating the need for manual operation of locking mechanisms. The system serves itself through gravitational force when tilted, providing automatic immobilization or movement capability.
2Force
If the chair is tilted to move it, then physical effort is reduced, but the risk of tipping increases
Solution Approach 1:
The patent uses dynamic tilting of the chair to control castor engagement. By tilting the chair forward or backward, the castors automatically engage or disengage, allowing easy movement without excessive physical effort while maintaining stability through controlled positioning.
Solution Approach 2:
The design prevents tipping by ensuring that tilting only occurs within safe limits that engage castors before the chair can tip over. The mechanical geometry is designed so that the chair must be tilted significantly to engage castors, providing a safety margin against accidental tipping.
3Ease of operation
If wheels are used for easy movement, then the chair can be moved effortlessly, but it cannot remain stationary without active locking
Solution Approach 1:
The patent uses a dynamic tilting mechanism to control wheel engagement. When the chair is tilted forward, the wheels engage with the ground for effortless movement. When tilted back to the normal position, the wheels disengage and the chair remains stationary without requiring active locking mechanisms.
Solution Approach 2:
The chair automatically engages or disengages wheels based on its tilt position, eliminating the need for manual locking mechanisms. The system uses gravity and geometry to self-regulate movement and stationary states.
4Ease of operation
If the chair design is modified for mobility, then movement capability is improved, but adaptability to existing furniture decreases
Solution Approach 1:
The patent segments the chair into functional modules: the seat structure remains unchanged to maintain compatibility with existing furniture, while the mobility function is added through separately attachable castors and a tilting mechanism that can be integrated into various chair designs.
Solution Approach 2:
The tilting mechanism and castor system are designed to be universally applicable to different chair types. The pedal and tilting geometry can be adapted to various chair structures, allowing the same basic mechanism to provide mobility enhancement across multiple furniture designs.
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
Reduces physical effort required to move chairs, prevents untimely movements, and maintains ergonomic safety for assistants, while being adaptable to existing furniture without compromising aesthetics.
Implementation Method 1
a roller (22) able to move forward by rolling
Implementation Method 2
act on the operating pedal (32) with his foot so as to tilt the chair (12) forward
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5E
AI summary
The invention relates to an item of furniture (12) including a total of four front (18-1, 18-2) and rear (18-3, 18-4) legs that are provided with moving means. Said rear moving means (20-2) are provided with a stowable controlling means (28) that includes at least one wheel (22), supported on a shaft (30) defining an axis XX' and mounted in a freely rotatable manner. The ends of said shaft have offsets (36), each with a pin (38) secured to the rear legs (18-3, 18-4), thus defining an axis YY' positioned towards the front with respect to the axis XX' so that said movement means can take a stable stowed position and an unstable projected position.