Seat Belt Retractor Pawl Holding Unit for Locking Deep Mitigation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Seat belt retractors experience locking deep and overshoot phenomena, leading to increased load on the driver's body and potential injury, due to delays in the emergency locking retractor's operation and residual gas pressure hindering the load limiter's performance.

Innovation Solution

A retractor design featuring a pawl member holding unit with a cam protrusion and rotating member that restricts the pawl member's protrusion and applies force to restore it, combined with an overshoot mitigating module that rotates the torsion bar to prevent load increases, minimizing the impact of gas residual pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the emergency locking retractor operates after the pretensioner, then the locking function is activated, but a delay occurs causing locking deep phenomenon and rapid load decrease

Engineering Contradiction:

Improvelocking function activationVSAvoidoperation delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The pawl member is pre-restricted by the rotating member before the emergency locking retractor operates. The cam protrusion is positioned to advance the rotating member, which applies force to the pawl member in advance, preventing delay in locking activation and avoiding locking deep phenomenon.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The rotating member applies force to the pawl member in advance to prevent its protrusion. This preliminary anti-action counteracts the potential delay in emergency locking retractor operation, ensuring immediate locking response when collision occurs.

Inventive Principle:

Principle #9Preliminary anti-action

2Force

If the gas generator residual pressure remains high, then the pretensioner operation continues, but it hinders the load limiter and emergency locking retractor operations causing overshoot phenomenon

Engineering Contradiction:

Improvepretensioner forceVSAvoidload limiter operation

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The rotating member acts as an intermediary between the cam protrusion and the pawl member. It translates the cam protrusion's movement into controlled force application on the pawl member, enabling precise restriction that prevents overshoot while allowing necessary operations despite residual gas pressure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The cam protrusion changes the positional parameter of the rotating member, which in turn changes the force parameter applied to the pawl member. This parameter transformation allows controlled restriction of the pawl member to prevent overshoot phenomenon caused by residual gas pressure.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the pawl member protrudes outward, then the automatic locking function operates, but it causes locking deep phenomenon and driver injury

Engineering Contradiction:

Improveautomatic locking functionVSAvoiddriver injury

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The rotating member applies a counter-force to the pawl member's protrusion tendency. By applying force in the opposite direction to the pawl member's outward movement, it prevents excessive protrusion that would cause locking deep phenomenon and driver injury.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The pawl member is restricted in advance by the rotating member before collision occurs. This preliminary restriction prevents the pawl member from protruding outward during the locking operation, eliminating the harmful effect of locking deep phenomenon.

Inventive Principle:

Principle #10Preliminary action

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 solution effectively prevents locking deep and overshoot phenomena, reducing the risk of injury by ensuring stable load distribution and reliable operation of the seat belt during collisions, while maintaining a simple and reliable structure.

Implementation Method 1

a cam protrusion which is provided at the other side of a torsion bar that is provided inside a spool, shares a rotation axis with the spool, and rotates together with the spool, the cam protrusion moving in accordance with the rotation of the torsion bar

Methodology Applied

Scientific EffectCam mechanism: Cam

Implementation Method 2

a torsion bar that is provided inside a spool, shares a rotation axis with the spool, and rotates together with the spool

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS10259424B2Pawl member holding unit of retractor for seat belt and retractor for seat belt having the same

Publication Date: 2019.04.16 WOOSHIN SAFETY SYST CO LTD

AI summary

A pawl member holding unit of a retractor for a seat belt includes: a cam protrusion which is provided at the other side of a torsion bar that is provided inside a spool, shares a rotation axis with the spool, and rotates together with the spool, the cam protrusion moving in accordance with the rotation of the torsion bar by an operation of a pretensioner; and a rotating member which rotates about a rotating shaft in accordance with the movement of the cam protrusion, and applies external force in a direction opposite to a direction in which a pawl member, which performs an automatic locking function, protrudes.