Retract Cable Control for Wheelchair Restraint Release
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wheelchair occupants are physically incapable of releasing the restraint belt retractor system in bus or similar vehicles, as the anchor point is out of reach, making it difficult to unhook the securing straps upon arrival at the destination.
Innovation Solution
A control device with a latch portion, cable, displacement portion, and solenoid unit that allows the latch to move between locked and released positions, with a timing circuit to automatically suspend the latch in the released position for a predetermined time, enabling easy operation of the restraint belt retractor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the anchor point is positioned out of reach for wheelchair occupants, then the restraint system provides secure anchoring, but the occupant cannot physically release the retractor
Solution Approach 1:
A cable connects the latch portion (within reach) to the retractor trigger (out of reach), serving as a mechanical intermediary that transmits force over distance. The cable allows the occupant to operate the retractor release from a reachable position while maintaining secure anchoring through the same cable mechanism.
Solution Approach 2:
The manual direct-operation mechanical system is replaced with a remote-operated mechanical system using the cable and latch mechanism. This substitution allows the release function to be actuated from a different location than where the retractor is physically located.
2Ease of operation
If the latch portion is held in the released position continuously, then the wheelchair can be easily detached, but the restraint system cannot provide secure locking during travel
Solution Approach 1:
The latch portion alternates between locked and released positions in periodic cycles. During travel, the latch remains in the locked position providing secure anchoring. At destination, it transitions to the released position allowing detachment. This periodic switching resolves the contradiction between continuous security and ease of detachment.
Solution Approach 2:
The latch portion is designed to be dynamically switchable between two stable states (locked and released) rather than remaining static. The spring element provides dynamic restoration to the locked position, while the cable mechanism enables dynamic transition to the released position when needed.
3Reliability
If a spring element biases the latch toward the locked position, then the restraint system maintains secure locking, but additional components increase device complexity
Solution Approach 1:
The spring element provides self-service by automatically returning the latch portion to the locked position after release, without requiring additional actuators or complex control systems. The spring's elastic energy stores and releases automatically perform the locking function, simplifying the overall system despite adding one component.
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 wheelchair occupants to securely attach or detach the wheelchair by automatically maintaining the restraint belt retractor in a released position for a sufficient time, allowing for easy manipulation of the wheelchair at the destination.
Implementation Method 1
the solenoid unit being operable under a control signal to fix the position of the plunger
Implementation Method 2
a spring element operating between the central segment and latch portion to bias the latch portion toward the first position
Data Source
AI summary
A control device for controlling a restraint belt retractor, comprises a latch portion, a cable with a first end arranged to be joined to the latch portion and a second end arranged to be operatively associated with the restraint belt retractor, the latch portion being movable between a first position in which the cable is arranged to maintain the restraint belt retractor in a locked position and a second position in which the cable is arranged to maintain the restraint belt retractor in a released position, a displacement portion for displacing the latch portion between the first and second positions, the latch portion being biased toward the first position, a suspension portion for suspending the latch portion at or near the second position for a predetermined period of time, thereby to permit operation of the restraint belt retractor in the released position.