Sliding Door Folding Threshold for Wheelchair Rail Crossing

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Solution Overview

Problem

Existing sliding doors with rails pose challenges for individuals with disabilities and small-wheeled devices due to obstruction and safety issues, requiring separate operations and invasive modifications, and current solutions are difficult to standardize and adapt.

Innovation Solution

A folding threshold system that synchronizes with the sliding door's opening and closing motion, automatically adjusting to cover the rail cavity without separate drives, using the door's kinetic energy for operation, and requiring minimal modifications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a rail is present in sliding doors, then structural support and guidance are provided, but accessibility for wheelchairs and small-wheeled devices is hindered

Engineering Contradiction:
Improvestructural supportVSAvoidaccessibility
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The patent applies the dynamics principle by making the threshold movable rather than fixed. The threshold can dynamically change its position between covering the rail cavity when the door is closed and retracting when the door opens, allowing it to adapt to different operational states and resolve the contradiction between providing structural support and ensuring accessibility.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent introduces a threshold as an intermediary element between the rail structure and the wheelchair/user. This threshold mediates the interaction by covering the cavity to provide support when needed while retracting to allow passage, thus resolving the conflict between structural requirements and accessibility.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If accessory ramps and slides are added to facilitate threshold crossing, then accessibility is improved, but device complexity and operational complexity increase

Engineering Contradiction:
ImproveaccessibilityVSAvoidsystem complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent merges the threshold function with the door assembly itself, integrating the accessibility feature into the existing door structure rather than adding separate autonomous systems. This combination reduces overall system complexity while maintaining accessibility benefits.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The threshold is designed to operate automatically based on the door's position, using the door's own motion to trigger threshold retraction or coverage. This self-service mechanism eliminates the need for separate control systems, motors, or complex coordination between multiple independent components.

Inventive Principle:
Principle #25Self-service

3Ease of operation

If accessory ramps and slides are added to facilitate threshold crossing, then accessibility is improved, but installation invasiveness increases

Engineering Contradiction:
ImproveaccessibilityVSAvoidinstallation invasiveness
Core Design Contradiction:
Ease of operationVSEase of manufacture

Solution Approach 1:

The patent designs a universal threshold solution that can be integrated into various sliding door configurations without requiring extensive custom modifications. The threshold serves multiple functions (covering the cavity, providing support, enabling accessibility) and can be adapted to different door types, reducing installation invasiveness.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Extent of automation

If separate drives are used for threshold coverage, then threshold control is achieved, but operational synchronization and reliability decrease

Engineering Contradiction:
Improvethreshold controlVSAvoidsynchronization reliability
Core Design Contradiction:
Extent of automationVSReliability

Solution Approach 1:

The threshold system uses the door's own motion as the actuating force, eliminating the need for separate motors or control systems. The door's opening and closing movements automatically trigger the threshold to retract or cover the cavity, ensuring perfect synchronization and high reliability without additional control complexity.

Inventive Principle:
Principle #25Self-service

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

Facilitates safe and seamless passage for wheelchairs and similar devices by automatically adapting to the door's motion, maintaining functionality and compliance with architectural barriers without additional complexity.

Implementation Method 1

said folding flap (1) being operated by means of a leverage (7) contained in a unit (8) having a shape preferably similar to said lower profile (3) of said sliding door (5)

Methodology Applied
Scientific EffectGravity: Gravitation

Implementation Method 2

said synchronism being determined as anticipated by a suitable leverage (7) which allows during the closing phase of the sliding door (5) to convert the kinetic energy of said leaf (6) into a mechanical impulse which overturns said flap

Methodology Applied
Scientific EffectKinetic energy conversion: Mechanical Advantage

Data Source

PatentEP4522838B1Adaptive threshold for sliding doors
Publication Date: 2026.01.21 WINGECO SRL
  • EP4522838B1 patent drawingFigure 1
  • EP4522838B1 patent drawingFigure 2
  • EP4522838B1 patent drawingFigure 3

AI summary

The patent consists of a flap which can be employed for covering the cavity corresponding to the lower profile of a sliding window when the sash opens. Said system subsequently allowing automatic withdrawal of said flap in a side-by-side position and not interfering with the sliding of said door during closing: said automatic withdrawal thus taking place in correspondence with the sliding in the opposite direction of the same door. This double synchronized movement with opening and closing of said sliding door favors the crossing of the threshold by users but above all by wheelchairs, trolleys, pushchairs and similar. The system object of the patent proposal is based on a mechanism controlled directly by the sliding of said sliding door which allows the automatic movement of said flap from a first horizontal position covering the frame track to a second lateral position next to the sliding door and vice versa.