Retractable Motor Vehicle Key with Tapered Insert Clearance

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Solution Overview

Problem

Retractable motor vehicle keys with large clearance at the end of the bit exhibit premature wear of the opening/closing mechanism and give a fragile impression due to induced friction, affecting usability.

Innovation Solution

The key design incorporates a sector of evolution with a narrowing point that reduces the second clearance to 0.05 millimeters, ensuring the first clearance of 0.2 millimeters remains effective for deployment without blocking rotation, by making the upper and lower movement zones non-parallel and introducing a narrowing point at the locking end or inclined surface within the evolution sector.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the insert is allowed to have large clearance when deployed, then the deployment mechanism can operate smoothly without blocking, but the opening/closing mechanism experiences premature wear due to induced friction

Engineering Contradiction:

Improvedeployment smoothnessVSAvoidmechanism durability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The invention applies different clearance characteristics to different zones of the insert's movement path. The first zone (from rest position to near end of travel) maintains larger clearance (0.1-0.3mm) for smooth operation, while the second zone (near end of travel) reduces clearance to 0.01-0.05mm to minimize friction and wear. This local differentiation resolves the contradiction between deployment smoothness and mechanism durability.

Inventive Principle:

Principle #3Local quality

2Reliability

If the clearance at the end of the bit is reduced, then wear is minimized, but the deployment mechanism may block rotation

Engineering Contradiction:

Improvemechanism durabilityVSAvoiddeployment smoothness

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The invention segments the insert's evolution sector into two distinct zones with different clearance characteristics. The first zone allows larger clearance for smooth deployment, while the second zone (near the end) provides minimal clearance to reduce wear. This segmentation enables both smooth operation and reduced wear by providing appropriate clearance characteristics in different parts of the movement path.

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If uniform clearance is maintained throughout the evolution sector, then manufacturing is simplified, but lateral friction increases causing premature wear

Engineering Contradiction:

Improveclearance uniformityVSAvoidmechanism durability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention implements non-uniform clearance distribution within the evolution sector by defining two zones with different clearance values. The first zone has larger clearance (0.1-0.3mm) and the second zone has minimal clearance (0.01-0.05mm). This local quality differentiation reduces lateral friction and wear in the critical end region while maintaining manufacturability through defined geometric parameters.

Inventive Principle:

Principle #3Local quality

4Device complexity

If the evolution sector is made parallel, then the structure is simpler, but the key gives a fragile impression due to excessive clearance

Engineering Contradiction:

Improveevolution sector structureVSAvoiduser perception of robustness

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The invention creates a narrowing point within the evolution sector where the clearance progressively reduces toward the end of the insert. This produces a tapered or converging geometry rather than parallel walls, which provides visual feedback to the user that the key is firmly engaged and reduces the fragile impression, while maintaining reasonable structural complexity.

Inventive Principle:

Principle #3Local quality

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

This design reduces wear and enhances the key's perceived robustness by minimizing lateral clearance, improving mechanical efficiency and user experience.

Implementation Method 1

an elastic return element 23 fixed by a first end 23a to the insert 5.7 and by a second end 23b to an element locked in rotation relative to the housing 3, to urge the insert 5.7 to pivot towards the position of use when the push button 19 is actuated

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

This return element 23 is a helical torsion spring

Methodology Applied

Scientific EffectTorsion Spring: Torsion Spring

Data Source

PatentEP2935729B1Key having a retractable insert with limited clearance

Publication Date: 2017.02.15 VALEO SECURITE HABITACLE

AI summary

The present invention relates to a motor vehicle key, comprising: - a housing; - an insert (5; 7), - a mechanism for deploying the insert; - an upper rim (44) of a top area (43) of the support (5), and a lower rim (45) of a bottom area (42) of the support (5), the upper rim (44) and the lower rim (45) extending between a rotation end (46) of the key (1) and a blocking end (47), the top area (43) and the bottom area (42) forming a movement sector of the support (5); - a first clearance (31) between the rotation end (46) and the support (5); characterised in that the movement sector of the support (5) comprises at least one narrowing point having, with said support (5), a second clearance (32) smaller than the first clearance (31).