Seatbelt Restraint with Under-Seat Loop to Prevent Submarining
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Solution Overview
Problem
Three-point seat belts are ineffective in preventing submarining, a dangerous phenomenon where occupants slide out from under the belt during collisions, particularly affecting children and small adults, and existing solutions like five and six-point harness systems are cumbersome and costly.
Innovation Solution
A seat belt restraint system featuring a single, continuous belt with two releasably engageable buckle portions, anchored to an inertia reel mechanism, with a belt guide that passes beneath the seat to wrap around the legs and deploy pretensioning to prevent sliding, integrated with a standard three-point belt for enhanced security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a three-point seat belt is used, then the belt is simple and convenient for everyday use, but it allows occupants to submarine out during collisions
Solution Approach 1:
The seat belt system is divided into two separate belts: a standard three-point seat belt for normal use and a additional loop belt that passes under the seat and around the occupant's legs. This segmentation allows the simple three-point belt to maintain ease of operation while the loop belt provides enhanced submarining prevention through independent leg anchoring.
2Reliability
If five or six point harness systems are used, then submarining is prevented, but the system becomes cumbersome and uncomfortable for everyday use
Solution Approach 1:
The invention extracts only the essential anti-submarining function from complex five or six-point harness systems by implementing a simple loop belt that passes under the seat and around the legs. This extracted minimal configuration provides the necessary leg anchoring to prevent submarining without the excessive complexity and discomfort of full multi-point harnesses.
3Reliability
If connector members are added to prevent submarining, then restraint effectiveness is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The invention merges the anti-submarining function directly into the existing seat structure by routing the loop belt under the seat base and anchoring it to the seat frame. This integration eliminates the need for separate connector members and complex mechanical assemblies, achieving effective leg restraint through a simple continuous belt configuration that utilizes the seat structure itself as part of the restraint system.
4Reliability
If connector members are added to prevent submarining, then restraint effectiveness is improved, but the volume and flexibility of the system increase
Solution Approach 1:
The invention uses a flexible continuous loop belt that can be routed under the seat and around the occupant's legs without requiring rigid connector members or large mechanical assemblies. The flexible belt configuration adapts to the available space within the seat structure, providing effective leg anchoring with minimal volume requirements and maintaining the compact integration needed for existing vehicle seats.
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 system effectively reduces the likelihood of submarining by securely wrapping the belt around the wearer's legs and torso, providing a cost-effective and flexible solution suitable for retrofitting vehicles, while minimizing abdominal injuries and enhancing overall restraint during collisions.
Implementation Method 1
anchored to an inertia reel mechanism
Data Source
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AI summary
Part of a seat belt, anchored at the top of the seat, adopts a conventional sash/belt arrangement (2a, 2c). The other end of the belt, however, passes under the seat base and protrudes up on the opposite side of the seat base to the above anchorage point. This other end carries a buckle to receive a conventional tongue which slides along the belt. Thus, in use, the belt encircles user's thighs (22) and the seat squab. In an accident a pretensioner activates which tightens the belt, somewhat raising and curling seat squab and user's legs (22), so preventing "submarining" (ie sliding of the user out from under the belt). Alternatively an existing lap/sash belt may be augmented by an extra belt passing from the seat top, across the chest, and around one thigh of the wearer.