ISOFIX Two-Lock Mechanism Preventing Connector Retraction

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Solution Overview

Problem

Existing ISOFIX retaining mechanisms for child safety seats do not effectively prevent the retraction of the ISOFIX connector after it is pulled out, which can lead to improper connection with the car interface.

Innovation Solution

An ISOFIX two-lock mechanism comprising a base, bracket, stopper, and limiting rod, where the stopper moves upward under the limiting rod's action and returns downward due to a spring mechanism, preventing the limiting rod from retracting by abutting against the stopper, and a button assembly with an inhaul cable and sliding block to facilitate controlled retraction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single-lock ISOFIX retaining mechanism is used, then the device complexity is reduced, but the reliability of preventing ISOFIX connector retraction is insufficient

Engineering Contradiction:
Improveprevention of ISOFIX connector retractionVSAvoidmechanism structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The retaining mechanism is divided into two independent locking systems: a first locking mechanism (stopper and guide rail) that locks the ISOFIX connector in the extended position, and a second locking mechanism (retaining component with retaining rod) that provides additional retention. This segmentation allows each mechanism to perform its specific function, ensuring reliable prevention of retraction while maintaining clear functional separation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The retaining component is rotatably arranged on the bottom surface of the base, with the retaining rod extending downward to engage with the ISOFIX connector. The elastic element is arranged between the retaining rotary block and the bottom surface, creating a nested structure where multiple components work together in a compact arrangement, achieving reliable retention without excessive complexity.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Ease of operation

If the ISOFIX connector is allowed to move freely during installation, then the ease of operation is improved, but the reliability of connection to car interface deteriorates

Engineering Contradiction:
Improveinstallation processVSAvoidconnection to car interface
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The first locking mechanism (stopper on guide rail) is designed to automatically engage when the ISOFIX connector is pulled out to the extended position. The stopper moves along the guide rail and abuts against the connecting end, preliminarily securing the connector before final connection to the car interface. This preliminary locking action ensures the connector remains in the correct position during the connection process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The second locking mechanism (retaining component) provides preliminary anti-action by preventing retraction of the ISOFIX connector. The retaining rod engages with the connector and, under the action of the elastic element, creates a counter-force that opposes any retraction movement. This preliminary prevention of retraction ensures the connector maintains its extended position for reliable connection.

Inventive Principle:
Principle #9Preliminary anti-action

3Reliability

If the stopping rod is used to prevent retraction, then the device complexity is reduced, but the reliability of preventing retraction deteriorates

Engineering Contradiction:
Improveprevention of retractionVSAvoidlocking mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The retaining component is designed to be rotatable on the bottom surface of the base, allowing it to dynamically adjust its position. The retaining rod can move between engaged and disengaged states, providing dynamic retention control. This dynamic design enhances reliability by allowing the mechanism to adapt to different operational states while maintaining a relatively simple overall structure.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The elastic element automatically applies force to the retaining rod, creating a self-service locking action. When the ISOFIX connector is extended, the elastic element pushes the retaining rod into engagement with the connector, automatically preventing retraction without requiring additional actuation mechanisms. This self-service feature enhances reliability while minimizing added complexity.

Inventive Principle:
Principle #25Self-service

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 mechanism securely prevents the ISOFIX assembly from retracting, ensuring smooth connection to the car interface and allowing controlled retraction when needed.

Implementation Method 1

the stopper return spring elastically deforms

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

the button return spring abuts against the limiting portion

Methodology Applied
Scientific EffectElastic force: Elasticity

Data Source

PatentEP3825171B1Isofix two-lock mechanism for retaining
Publication Date: 2022.11.16 NINGBO BABY FIRST BABY PROD CO LTD
  • EP3825171B1 patent drawingFigure 1
  • EP3825171B1 patent drawingFigure 2
  • EP3825171B1 patent drawingFigure 3

AI summary

An ISOFIX two-lock mechanism for retaining, comprising a base (1) and an ISOFIX assembly (2); a bracket (16) is provided at the upper end of the base (1), the bracket (16) being provided with a channel (17), the channel (17) being provided with a stopper (18) therein, a stopper bevel (22) being provided at the lower end of the stopper (18), a stopper return spring (21) being connected between the stopper (18) and the bracket (16); and the ISOFIX assembly (2) comprises a limiting rod (13), when the limiting rod (13) moves into abutment against the stopper bevel (22), the stopper (18) moving upward along the channel (17), and the stopper return spring (21) elastically deforming; and when the limiting rod (13) moves further and away from the abutment against the stopper (18), the stopper (18) moving downward under the action of the stopper return spring (21) until a plane of the stopper (18) abuts against the limiting rod (13).