Webbing Retractor Gas Venting Guide Wall

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Solution Overview

Problem

In webbing retractors with both pretensioner and acceleration detecting mechanisms on the same side of the spool, the exhaust gas from the pretensioner mechanism can interfere with the acceleration detecting mechanism, causing operational issues.

Innovation Solution

A guide wall or blocking wall is strategically placed to direct the exhaust gas away from the acceleration detecting mechanism, preventing interference and ensuring proper operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If both the pretensioner mechanism and the acceleration detecting mechanism are disposed at the same side of the spool, then the device complexity is reduced, but the exhaust gas from the pretensioner mechanism interferes with the acceleration detecting mechanism

Engineering Contradiction:

Improvearrangement of mechanismsVSAvoidgas interference

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The housing is divided into multiple chambers: a first chamber for the acceleration detecting mechanism and a second chamber for the pretensioner mechanism. This spatial segmentation isolates the harmful exhaust gas from the acceleration detecting mechanism while maintaining a compact overall structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A partition wall with a gas blocking portion is introduced as an intermediary structure between the two mechanisms. This partition wall allows the acceleration detecting mechanism to function normally by blocking the harmful exhaust gas from reaching it, while permitting necessary mechanical interactions through the gas blocking portion.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Stability of the object's composition

If the pretensioner mechanism and acceleration detecting mechanism are placed on opposite sides of the frame, then the balance of placement is improved, but the device complexity and space requirements increase

Engineering Contradiction:

Improvebalance of placementVSAvoidarrangement of mechanisms

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

Both the acceleration detecting mechanism and the pretensioner mechanism are combined within the same housing structure, specifically within the same retractor assembly. This merging approach maintains spatial balance within a compact unit while using internal partitioning to manage gas interference, rather than requiring separate opposite-side placements.

Inventive Principle:

Principle #5Merging (Combining)

3Productivity

If mechanisms are compactly arranged to reduce space, then the productivity and space utilization are improved, but the exhaust gas cannot be properly directed away from sensitive components

Engineering Contradiction:

Improvespace utilizationVSAvoidgas interference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The partition wall extends in the axial direction of the spool, utilizing the third dimension (axial direction) to create effective separation between mechanisms. This dimensional approach allows compact radial arrangement while providing sufficient gas blocking capability through the extended partition structure.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The first and second chambers are nested within the same housing, with the partition wall creating internal separation. This nested arrangement allows both mechanisms to coexist in a compact space while maintaining the necessary isolation to prevent gas interference.

Inventive Principle:

Principle #7Nested doll (Nesting)

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 the exhaust gas from affecting the acceleration detecting mechanism, maintaining the integrity and accuracy of the webbing retractor's operation during emergencies.

Implementation Method 1

a pretensioner mechanism which rotates a take-up shaft in a take-up direction by gas pressure

Methodology Applied

Scientific EffectGas pressure: Pressure Increase

Implementation Method 2

a guide wall guiding exhausting direction of the gas exhausted from the pretensioner mechanism in a predetermined direction

Methodology Applied

Scientific EffectGas flow guidance: Fluid Spray

Data Source

PatentUS7624940B2Webbing retractor

Publication Date: 2009.12.01 KK TOKAI RIKA DENKI SEISAKUSHO

AI summary

A webbing retractor which can prevent gas, which is for rotating a take-up shaft in a take-up direction, from affecting other structural parts. In the webbing retractor, when a pretensioner mechanism operates, gas for operation within a cylinder is exhausted toward a pinion via a gas venting hole formed in a flange portion of a piston. Because a blocking wall is provided between the pinion and an acceleration sensor, exhausted gas passes between the pinion and the blocking wall, and is exhausted to an outer side of the webbing retractor from an upper end side of a cover plate or the like. In this way, blowing-out of the exhausted gas onto the acceleration sensor is blocked, and the exhausted gas can be prevented from affecting the acceleration sensor.