Dual-Locking Reel Assembly with Multi-Tooth Dog for Seatbelt Restraint
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Solution Overview
Problem
Existing reel assemblies for passenger restraint systems lack separate locking mechanisms that can be independently triggered and released for different incident types, and they fail to maintain a minimum holding force of 22.2 kN (5,000 pound force) with 90% of the webbing on the spool during extended periods.
Innovation Solution
A dual locking mechanism reel assembly with a first locking mechanism triggered by major incidents and a second by minor incidents, where the first mechanism remains locked until a reset button is accessed, and the second is reset by counter tension, utilizing a double-toothed locking dog to distribute load and prevent shearing failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single locking mechanism is used in the reel assembly, then the structure is simple, but it cannot provide separate locking for major and minor incidents, causing nuisance locking during non-critical events
Solution Approach 1:
The locking mechanism is segmented into two independent subsystems: a first locking mechanism with a first locking dog for major incidents, and a second locking mechanism with a second locking dog for minor incidents. Each locking dog can be independently triggered and reset, allowing the system to respond differently to major versus minor incidents without causing nuisance locking.
Solution Approach 2:
The locking dogs are designed with different reset characteristics: the first locking dog requires manual intervention via a reset button after major incidents, while the second locking dog can be automatically reset through counter-tension application. This dynamic differentiation allows appropriate response levels for different incident severities.
2Strength
If a single tooth locking dog is used, then the structure is simple, but it cannot maintain the required holding force of 22.2 kN with 90% webbing on the spool without shearing failures
Solution Approach 1:
The locking dog is divided into multiple teeth (first tooth and second tooth) instead of a single tooth design. This segmentation distributes the load across multiple engagement points, preventing shearing failures and enabling the locking dog to maintain the required holding force of 22.2 kN with 90% webbing on the spool.
Solution Approach 2:
The multiple tooth design provides redundant load paths before failure occurs. If one tooth experiences excessive stress, the other teeth continue to provide holding force, preventing catastrophic failure and ensuring the system maintains its strength requirement under extended loading conditions.
3Reliability
If the locking mechanism is designed for high holding force, then safety is improved, but the reset process becomes more complex and time-consuming
Solution Approach 1:
The reset process is segmented into two independent pathways: manual reset via a push button for the first locking dog after major incidents, and automatic reset through counter-tension application for the second locking dog after minor incidents. This segmentation allows the system to maintain high reliability while providing appropriate ease of operation for different incident types.
Solution Approach 2:
The second locking dog is designed to reset automatically through counter-tension application without requiring manual intervention, allowing the system to service itself for minor incidents. This self-service capability maintains safety reliability while simplifying the reset process for non-critical events.
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
The dual locking mechanism effectively restrains occupants during both major and minor incidents while maintaining a holding force of 22.2 kN (5,000 pound force) with 90% of the webbing on the spool, reducing the risk of shearing failures and allowing for efficient reset after incidents.
Implementation Method 1
When a strap is rapidly pulled from the reel, an inertia mass turns with respect to the reel. This causes the inertia mass to move forward axially and trip a dog which locks the reel.
Implementation Method 2
a double-toothed locking dog to distribute load and prevent shearing failures
Data Source
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AI summary
Disclosed is an improved reel assembly for use in conjunction with an occupant restraint system. The assembly employs a dual locking arrangement whereby an occupant can be restrained during both major and minor incidents. After a minor incident, the reel assembly can be conveniently unlocked, without the need for accessing the push button, by applying counter tension to the webbing. After a major incident, the reel assembly remains locked until the occupant disengages the reel via a push button. When the reel assembly experiences the force of a major incident, rotation of the webbing shaft may be first partially arrested by the engagement of a first of two locking teeth on a locking dog with a first of two engagement surfaces on a geared end plate and subsequently completely arrested by the combined engagements of the first and second locking teeth with their respective first and second engagement surfaces.