Support Leg Rebound Locking for Child Seat Rotation Control

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Solution Overview

Problem

Child safety seats in vehicles can rotate about a lateral axis during collisions, leading to potential injuries due to uncontrolled rebound and rotation, especially in rear-end collisions, which existing mechanisms like Isofix and top tethers do not adequately address.

Innovation Solution

A child safety seat with a pivotally connected support leg and a locking mechanism that allows inward pivoting during impact but limits outward swing during the rebound phase, using a pawl and biasing member to control the support leg's movement and prevent it from returning to its initial position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a support leg is used to prevent rotation of the child safety seat about the lateral axis, then the stability of the seat is improved, but the support leg may swing uncontrolled during the rebound phase causing harmful effects

Engineering Contradiction:

Improveseat stabilityVSAvoiduncontrolled rebound swing

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The locking mechanism dynamically changes the support leg's state from movable (during impact) to fixed (during rebound). The pawl and ratchet arrangement allows the leg to pivot inward during collision but prevents outward swing during rebound, adapting the leg's degrees of freedom based on the collision phase.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The locking mechanism converts the harmful uncontrolled rebound swing into a beneficial controlled position. By allowing the support leg to pivot inward during impact and then locking it in place, the mechanism transforms the potentially harmful rebound motion into a stable, controlled configuration that prevents head and neck injuries.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If a locking mechanism is added to control the support leg during rebound, then the safety is improved, but the device complexity increases

Engineering Contradiction:

ImprovesafetyVSAvoidmechanism complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The locking mechanism is self-activating through the force of the rebound itself. The pawl and ratchet arrangement automatically engages when the support leg attempts to swing outward during rebound, requiring no external control systems, sensors, or additional power sources. The mechanism uses the rebound force itself to trigger the locking action.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The locking function is extracted as a separate, dedicated mechanism (pawl and ratchet) that can be independently analyzed and optimized. This modular approach allows the locking function to be added without fundamentally redesigning the entire support leg system, maintaining relative simplicity while achieving enhanced safety.

Inventive Principle:

Principle #2Taking out (Extraction)

3Loss of energy

If the support leg is allowed to pivot freely during impact, then the energy absorption is improved, but the rebound phase causes uncontrolled movement leading to injuries

Engineering Contradiction:

Improveimpact energy absorptionVSAvoidrebound injury risk

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The system dynamically transitions from a free-pivoting state during impact (allowing energy absorption) to a locked state during rebound (preventing injury). The pawl and ratchet mechanism enables this dynamic behavior by being disengaged during inward swing but engaging during outward swing, automatically adapting to the collision phase.

Inventive Principle:

Principle #15Dynamics

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

Reduces the risk of head and neck injuries by controlling the support leg's angle upon rebound, ensuring it lands in a position that cushions the child's head against the headrest, and potentially reducing the size and complexity of the seat.

Implementation Method 1

a biasing member which biases the pawl towards its disengaged position

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

during an accident where the leg swings inward, is activated by a forward acceleration of the seat

Methodology Applied

Scientific EffectInertia: Inertia

Data Source

PatentUS20260061901A1Support leg rebound lock

Publication Date: 2026.03.05 BRITAX ROMER KINDERSICHERHEIT GMBH

AI summary

The present disclosure relates to a foot prop or support leg for a child safety seat, a child safety seat, a seat base comprising such a foot prop and a child safety seat comprising such a foot prop or such a seat base. In one aspect, a support leg pivotally is connected with respect to a forward facing portion of the child safety seat so as to swing inward toward the seat and outward away from the seat, being characterised in that it further comprises a releasable locking means activated responsive to a forward acceleration of the seat to impose a limit to an extent of outward swing of the leg.