Self-locking Belt Retractor Spring-Loaded Control Disc

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Solution Overview

Problem

Conventional self-locking belt retractors experience unintentional blocking when the belt webbing is pulled out quickly, leading to a long unlocking path due to the interaction of belt-sensitive and vehicle-sensitive locking systems, requiring significant belt retraction and retraction to unlock the belt shaft.

Innovation Solution

A self-locking belt retractor design where the control disc is initially rotated slightly with the belt shaft at the start of the unlocking process, releasing sensors and allowing the inertia element to swing back, using a spring-loaded coupling mechanism to minimize disruption, and ensuring equal spring forces for locking and unlocking, allowing the belt shaft to be unlocked without further retraction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the belt webbing is pulled out quickly, then the belt-sensitive and vehicle-sensitive blocking systems respond, but the belt shaft is unintentionally blocked requiring a long unlocking path

Engineering Contradiction:
Improveblocking system responseVSAvoidunlocking path
Core Design Contradiction:
ReliabilityVSLength of moving object

Solution Approach 1:

The control disk is pre-loaded by a spring force in the unlocking direction. When unlocking is initiated, this pre-loaded spring force immediately acts to rotate the control disk and release the locking element, providing a head start in the unlocking process and reducing the total unlocking path required.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The spring force on the control disk is pre-loaded in the opposite direction (unlocking direction) rather than the locking direction. This inversion allows the control disk to be quickly released and rotated in the unlocking direction when the blocking system activates, enabling faster and shorter unlocking path.

Inventive Principle:
Principle #13The other way round (Inversion)

2Strength

If the locking element is engaged in the toothing of the housing, then the belt shaft is securely locked, but significant belt retraction is required to unlock the belt shaft

Engineering Contradiction:
Improvelocking engagementVSAvoidunlocking time
Core Design Contradiction:
StrengthVSLoss of time

Solution Approach 1:

The spring force on the control disk is pre-loaded in the unlocking direction, so when unlocking is needed, the control disk can be quickly rotated by this pre-existing spring force, significantly reducing the time and belt retraction needed to unlock the belt shaft while maintaining secure locking engagement.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The control disk is designed to be rotatable relative to the belt shaft under spring force, creating a dynamic system that can quickly transition from locked to unlocked state. This dynamic capability allows the control disk to rotate and disengage the locking element rapidly, reducing unlocking time and belt retraction distance.

Inventive Principle:
Principle #15Dynamics

3Reliability

If the control disc is stopped by the blocking lever, then the locking element is engaged in the toothing, but the modulation process requires full engagement resulting in long unlocking path

Engineering Contradiction:
Improvelocking engagementVSAvoidmodulation path
Core Design Contradiction:
ReliabilityVSLength of moving object

Solution Approach 1:

The spring force on the control disk is pre-loaded in the unlocking direction, providing an initial rotational impulse when the blocking lever engages. This preliminary spring action reduces the distance the control disk needs to travel during the modulation process, shortening the overall unlocking path while ensuring reliable locking engagement.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The spring force parameter on the control disk is optimized to provide sufficient force to rotate the control disk through the modulation process but not so much as to compromise locking engagement. This parameter optimization allows the control disk to complete the modulation process with minimal travel distance, reducing the unlocking path while maintaining reliable locking.

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

Enables the shortest possible unlocking path by releasing sensors and spring-loaded mechanisms, allowing the belt shaft to be unlocked with minimal movement, reducing the need for extensive belt retraction and improving the efficiency of the unlocking process.

Implementation Method 1

a belt shaft (10) which is rotatably mounted in a housing frame (5) and is prestressed by a winding spring (15) in the winding direction of the belt webbing (2)

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 2

a spring-loaded inertia element (13) that senses the acceleration of the belt webbing (2)

Methodology Applied
Scientific EffectInertia: Inertia

Implementation Method 3

The coupling should take place via a spring element (41), so that the coupling and decoupling can take place with as little disruption as possible to the blocking movement

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP2195209B1Self-locking belt retractor
Publication Date: 2016.03.30 AUTOLIV DEV AB
  • EP2195209B1 patent drawingFigure 1
  • EP2195209B1 patent drawingFigure 2~3
  • EP2195209B1 patent drawingFigure 4~5

AI summary

The invention relates to a self-locking belt retractor for seat belts having a belt shaft mounted in a rotary fashion in a housing frame and pre-tensed in the winding direction of the seat belt by a winding spring, a control disc (11) rotating with the belt shaft for controlling a locking member (21) displaceably disposed on the belt shaft until engagement in a housing tooth set (25), wherein the control disc (11) may be placed into relative rotation relative to the belt shaft by means of a spring-loaded inertia element (13) sensing the acceleration of the seat belt and/or a vehicle-sensitive acceleration sensor (30), wherein the locking member (21) is coupled to the control disc (11) when in the displaced state.