Gearbox Inertia Mass Ejection for Bulkhead Safety

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Solution Overview

Problem

Conventional inertia assemblies for motor vehicle gearbox control devices are bulky, heavy, and fail to meet safety standards during a frontal impact, causing bulkhead perforation and potential contact with the steering column, which compromises road safety and passenger protection.

Innovation Solution

An inertia assembly with an integral inertia mass capable of pivoting on the gearbox casing, featuring fusible zones and guiding means that allow the inertia mass to be ejected during an impact, preventing bulkhead perforation and steering column contact, while reducing mass through the use of a plastic body and cast iron arm, designed to break and redirect the inertia mass upon exceeding a specific force threshold.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional one-piece cast iron inertia assembly is used, then the inertia mass is sufficient for gear shifting, but the assembly becomes bulky and causes bulkhead perforation during impact

Engineering Contradiction:

Improvegear shifting performanceVSAvoidbulkhead perforation and steering column contact during impact

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The inertia assembly is divided into two separate blocks: a plastic body and a cast iron inertia mass. This segmentation allows the inertia mass to be ejected from the plastic body during impact through fusible zones, preventing bulkhead perforation while maintaining sufficient inertia for gear shifting operations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inertia mass is extracted as a separate ejectionable component from the body structure. During normal operation, it remains contained within the body to provide inertia; during impact, it is ejected through fusible zones to eliminate the harmful effect of bulkhead perforation and steering column contact.

Inventive Principle:

Principle #2Taking out (Extraction)

2Strength

If a conventional one-piece cast iron inertia assembly is used, then the structural integrity is maintained, but the mass is significant and increases vehicle weight

Engineering Contradiction:

Improvestructural integrityVSAvoidinertia assembly mass

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The inertia assembly uses a composite structure combining plastic material for the body and cast iron for the inertia mass. This composite approach reduces the overall mass compared to a conventional one-piece cast iron assembly while maintaining the necessary structural integrity and inertial properties through the strategic use of materials with different density and strength characteristics.

Inventive Principle:

Principle #40Composite materials

3Reliability

If the inertia mass is retained securely in the body, then the inertia assembly functions properly during gear shifting, but the inertia mass cannot be ejected during impact to prevent bulkhead perforation

Engineering Contradiction:

Improveinertia assembly function during gear shiftingVSAvoidbulkhead perforation during impact

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The retaining means (partitions) are designed with fusible zones that change their mechanical properties based on applied force parameters. During normal gear shifting, the partitions maintain sufficient strength to retain the inertia mass securely. During impact, when force exceeds a threshold, the fusible zones break, allowing the inertia mass to be ejected and preventing bulkhead perforation.

Inventive Principle:

Principle #35Parameter changes

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

Enhances vehicle and passenger safety by preventing bulkhead perforation and steering column contact during impacts, while achieving a mass reduction through the strategic design and material selection of the inertia assembly.

Implementation Method 1

the ejection means comprise fusible zones capable of breaking beyond a determined maximum force, applied thereto during an impact on the vehicle

Methodology Applied

Scientific EffectImpact force: Impact Force

Implementation Method 2

The weight constitutes the inertia mass of the inertia assembly making it possible to obtain a reduction in the vibrations felt at the level of the control device of the gearbox

Methodology Applied

Scientific EffectInertia: Inertia

Data Source

PatentEP1746310B1Inertial mass assembly for shifting device of a gear box

Publication Date: 2008.01.16 PEUGEOT CITROEN AUTOMOBILES SA

AI summary

In an inertia unit (1) comprising an inertial mass (2) firmly connected to a supporting body (3) which can pivot about an axis of rotation (XX') and is fixed to a gearbox casing, the supporting body is designed to eject the inertial mass in the case of impact. An independent claim is included for a gearbox comprising a gear changing lever in combination with the inertia unit.