Seat Belt Retractor Layout for Compact Tensioner Integration

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Solution Overview

Problem

Seatbelt retractors require a large installation space due to their external dimensions, which is problematic for integration into vehicle seats, especially when the seatbelt must withstand tensile forces and accommodate additional components like drive units and sensors.

Innovation Solution

A belt retractor design with a straight linear section extending parallel to the belt spool axis, incorporating a support rib and a frame with housing shells, allowing for a compact and efficient arrangement of components, including an irreversible belt tensioner and electric motor, within limited vehicle seat space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the seatbelt retractor is designed to withstand tensile forces with sufficient thickness and length, then the strength and reliability are improved, but the installation space requirement increases

Engineering Contradiction:
Improvetensile force resistanceVSAvoidinstallation space
Core Design Contradiction:
StrengthVSVolume of moving object

Solution Approach 1:

The tube is configured with a straight linear section extending parallel to the axis of rotation of the belt spool, utilizing the longitudinal dimension along the axis rather than expanding radially outward. This dimensional reorientation allows the tube to achieve sufficient length for strength while maintaining compact radial dimensions for installation space constraints.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The tube is arranged to extend through and alongside other components such as the gearbox and electric motor, effectively nesting the tube within the existing component layout. This allows the tube to achieve its required length without increasing the overall external dimensions of the retractor assembly.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If additional components such as drive unit, electric motor, and sensors are added to the belt retractor, then the functionality and reliability are improved, but the external dimensions and installation space requirement increase

Engineering Contradiction:
Improverestraint functionalityVSAvoidinstallation space
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The tube is designed to serve multiple functions simultaneously: it provides structural support for the belt spool, guides the seatbelt webbing, and extends alongside the drive unit and electric motor components. By merging these functions into a single integrated structure, the retractor achieves enhanced functionality without proportionally increasing installation space.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The linear section of the tube serves as both a structural support element and a space-efficient arrangement that accommodates multiple components (gearbox, electric motor, sensors) in its vicinity. This multi-functional design allows the tube to contribute to both mechanical strength and component integration.

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

3Productivity

If the belt spool is designed with sufficient width to retract the required amount of webbing, then the productivity is improved, but the installation space requirement increases

Engineering Contradiction:
Improvewebbing retraction capacityVSAvoidinstallation space
Core Design Contradiction:
ProductivityVSVolume of moving object

Solution Approach 1:

The tube extends parallel to the axis of rotation of the belt spool rather than radially outward from it. This orientation allows the tube to accommodate the longitudinal dimension of the belt spool's webbing capacity while maintaining compact radial dimensions, effectively decoupling the productivity dimension from the installation space dimension.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP4480761B1Belt retractor
Publication Date: 2026.03.25 AUTOLIV DEV AB
  • EP4480761B1 patent drawingFigure 1
  • EP4480761B1 patent drawingFigure 2
  • EP4480761B1 patent drawingFigure 3

AI summary

The invention relates to a belt retractor (40) with a belt spool (14), a safety belt (12) that can be wound onto it to form a belt roll, a pyrotechnic belt tensioner (24) with a drive unit guided in a tube (32) that can be driven to a drive movement, and at least one further assembly arranged coaxially to the axis of rotation of the belt spool (14) and in series with the belt spool (14), a safety belt (12) that can be wound onto it to form a belt roll, and at least one further assembly, wherein the tube (32) has a straight linear section (33) which extends parallel to the axis of rotation of the belt spool (14) and the longitudinal axis of the assembly and is arranged on the side of the belt spool (14) and the further assembly, wherein the linear section (33) is dimensioned in length such thatthat it extends over the length of the belt spool (14) in the direction of the axis of rotation of the belt spool (14) and over the length of the further assembly in the direction of the longitudinal axis.