Stroller Frame Folding and Locking Mechanism for One-Step Collapse

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Solution Overview

Problem

Conventional strollers require complicated operations to fold the frame, backrest, and seat portion, making them inconvenient to use.

Innovation Solution

A frame locking mechanism with a planar linkage mechanism that allows the handle, front foot, and rear foot to pivotally connect, enabling the frame and seat portion to fold in linkage, and a backrest unlocking mechanism that uses an unlock driving mechanism to disengage the backrest locking member.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a stroller is designed to be convertible between pushchair and pram modes, then versatility is improved, but device complexity increases due to multiple folding mechanisms and locking systems

Engineering Contradiction:
Improveconvertibility between pushchair and pram modesVSAvoidmultiple folding mechanisms and locking systems
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The stroller frame is designed with a universal folding mechanism that serves multiple functions: it enables conversion between pushchair and pram modes, provides standardized folding behavior across different configurations, and simplifies the overall system by using a single mechanism type throughout the structure

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The frame is divided into multiple modular components (first frame member, second frame member, backrest, seat unit) that can independently fold and lock, allowing the stroller to be converted between modes by simple relative movements of these segmented parts

Inventive Principle:
Principle #1Segmentation

2Volume of moving object

If the frame members are designed to fold relative to each other, then compactness is improved, but reliability decreases due to potential unintended folding or unlocking

Engineering Contradiction:
Improvecompactness when foldedVSAvoidstability against unintended folding or unlocking
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The locking mechanism is designed to automatically engage and lock the frame members in their folded position through the folding motion itself, preventing unintended unfolding. The detent feature and cam surface are pre-positioned to ensure automatic locking occurs as part of the folding action

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

A cam surface acts as an intermediary between the first and second frame members, mediating the folding motion and providing controlled engagement with the detent feature to ensure reliable locking without requiring additional complex mechanisms

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If the backrest is unlocked to enable folding, then ease of operation is improved, but safety decreases due to risk of unintended unlocking

Engineering Contradiction:
Improveease of backrest foldingVSAvoidsafety against unintended unlocking
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The locking mechanism provides tactile and positional feedback to indicate when the backrest is securely locked or unlocked, allowing the user to verify the state without visual inspection. The mechanism only allows unlocking when intentionally activated through the release button

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The unlocking function is extracted as a separate, intentional action requiring activation of a release button, distinct from the normal folding motion. This separates the safety-critical unlocking function from the routine folding operation, preventing accidental unlocking

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP4087768B1Frame folding mechanism, frame locking mechanism, backrest unlocking mechanism and stroller
Publication Date: 2026.04.22 WONDERLAND SWITZERLAND AG
  • EP4087768B1 patent drawingFigure 1
  • EP4087768B1 patent drawingFigure 2
  • EP4087768B1 patent drawingFigure 3

AI summary

The invention provides a frame folding mechanism (101), a frame locking mechanism (102), a backrest unlocking mechanism (103) and a stroller (100). A handle (11), a front foot (12), a seat portion (2) and a linking member (3) of the frame folding mechanism (101) form a planar linkage mechanism. The handle (11) and the front foot (12) can be driven to rotate and fold toward a rear foot (13), so as to drive the seat portion (2) to rotate and fold. The frame locking mechanism (102) can drive a sliding member (6) and a frame expansion locking member (7) to slide by an unlock driving mechanism (8), such that the frame expansion locking member (7) disengages from a handle locking hole (114) and a front foot locking hole (123) to unlock a frame (1). The backrest unlocking mechanism (103) has a backrest locking member (9). The unlock driving mechanism (8) can drive the backrest locking member (9) to slide, such that the backrest locking member (9) disengages from a backrest portion (4) to unlock the backrest portion (4).