Closed-Loop Wheelchair Restraint Assembly for Heavy Transit Securement
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Solution Overview
Problem
Current wheelchair securement systems, such as retractor and manual belt tie-downs, are inadequate for securing heavier wheelchairs in smaller vehicles due to limitations in strength, space, and installation complexity, leading to increased clutter, misuse, and higher costs.
Innovation Solution
A securement assembly featuring a retractor with a closed-loop restraint webbing that doubles the restraint between the wheelchair and vehicle, reducing clutter and installation complexity while maintaining retractor size and functionality, allowing securement of heavier wheelchairs without the need for multiple tie-downs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If retractor type tie-downs are used to secure wheelchairs, then installation is simplified and clutter is reduced, but the strength and weight capacity are limited to 100-120 kg
Solution Approach 1:
The patent combines the advantages of both retractor-type and manual belt-type tie-downs into a single hybrid device. The retractor mechanism provides automated deployment and retrieval with minimal user effort, while the manual adjustment features (ratchet or over-center buckle) enable strength adjustment and locking capability. This merging allows the system to achieve both ease of operation and high strength capacity for wheelchairs up to 140 kg and beyond.
2Strength
If manual belt type tie-downs are used to increase strength capacity, then wheelchairs up to 140 kg can be secured, but operation becomes more cumbersome and installation more complex
Solution Approach 1:
The retractor mechanism performs the preliminary action of automatically deploying the restraint webbing to the required length, eliminating the need for users to manually measure, cut, or adjust the webbing length. The retractor also automatically reels in the webbing after use. This preliminary automated action significantly reduces operational complexity while the manual adjustment mechanism (ratchet or over-center buckle) provides the necessary strength control and locking capability for heavy wheelchairs.
3Strength
If more than two retractors are used to secure heavier wheelchairs, then weight capacity increases, but clutter on vehicle floor increases and installation cost increases
Solution Approach 1:
The hybrid tie-down device is designed as a universal solution that can secure wheelchairs of varying weights (from standard to heavy-duty up to 140 kg and beyond) using a single device type. The multi-functionality is achieved through the combination of retractor mechanism for automated operation and manual adjustment features for strength control. This eliminates the need to use multiple standard retractors (three or more) for heavy wheelchairs, reducing clutter and installation complexity while maintaining adequate weight capacity.
4Strength
If restraint strength is increased by using thicker restraint material, then weight capacity increases, but retractor size and weight increase making installation more difficult
Solution Approach 1:
The patent merges the retractor mechanism with manual adjustment features (ratchet or over-center buckle) to achieve high restraint strength without requiring excessively thick restraint material or oversized retractors. The manual adjustment mechanism allows the system to optimize the restraint configuration for heavy wheelchairs by enabling the user to tighten and lock the webbing at the optimal tension point, thereby maximizing the effective strength of the existing restraint material and retractor size.
Data Source
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AI summary
The restraint and retractor assembly described and claimed herein are for securing a wheelchair to a support while the wheelchair is in transit. In one embodiment, the system includes at least one securement assembly having a configuration in which a portion of the wheelchair is secured in the vehicle. In this embodiment, the securement assembly includes a retractor secured to the vehicle and a restraint that has both of its ends secured to or near the retractor and a middle segment extends to and from a spool in the retractor, a middle segment is connected to the wheelchair by a connector and passes through an opening in the connector, providing a double length of flexible webbing to secure the wheelchair to the support surface.