Seat Belt Retract Spindle Recessed Insertion

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Solution Overview

Problem

The existing methods for assembling a seatbelt retractor require deformation of the retractor frame or additional components when a load limiter mechanism with a larger diameter is attached, complicating the process and increasing costs.

Innovation Solution

A spindle with a recessed portion on its cylindrical surface is designed to be inserted into a retractor frame with flat plate-shaped side walls, allowing the spindle to be tilted and inserted without deforming the frame, using a recessed portion that brings the deepest portion into contact with the through hole edge, enabling easy incorporation without additional components or steps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the diameter of the circular through hole in the retractor frame is increased to accommodate a spindle with a load limiter mechanism, then the spindle can be inserted from the outer side, but additional components (plate with smaller through hole) are required to support the pinion sliding motion

Engineering Contradiction:

Improvespindle insertion easeVSAvoidnumber of components

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

Instead of inserting the spindle from the outer side through an enlarged through hole (conventional approach), the invention inserts the spindle from the inner side of the retractor frame. The recessed portion on the spindle's cylindrical surface enables this reverse insertion method, allowing the spindle to be tilted and inserted without requiring additional plates or enlarging the through hole, thus maintaining structural simplicity.

Inventive Principle:

Principle #13The other way round (Inversion)

2Productivity

If the circular through hole in the retractor frame is enlarged to allow spindle insertion, then assembly is simplified, but the pinion sliding motion relative to load bearings becomes problematic requiring additional plates

Engineering Contradiction:

Improveassembly speedVSAvoidstructural complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The invention inverts the conventional insertion direction by inserting the spindle from the inner side rather than the outer side. The recessed portion geometry enables this reverse approach, allowing rapid assembly without enlarging the through hole and avoiding the need for additional plates to accommodate pinion sliding, thus maintaining both high productivity and structural simplicity.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The invention introduces a dimensional solution by creating a recessed portion (radial dimension) on the spindle's cylindrical surface. This radial recess allows the spindle to be inserted at an angle (tilted insertion) from the inner side, effectively adding a third dimension to the insertion process and eliminating the need for additional plates while maintaining the original through hole dimensions.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If additional components are added to support pinion sliding in an enlarged through hole configuration, then the pinion can function properly, but the assembly process becomes more complex with additional operational steps

Engineering Contradiction:

Improvepinion sliding supportVSAvoidassembly process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention eliminates the need for additional support components by inverting the insertion approach. The recessed portion enables direct insertion from the inner side, and the pinion sliding function is achieved through the original load bearings without requiring additional plates, thus maintaining reliability while simplifying the assembly process to a single operation.

Inventive Principle:

Principle #13The other way round (Inversion)

4Reliability

If bearings are added to support spindle end portions in an enlarged through hole configuration, then spindle support is improved, but costs increase due to additional components

Engineering Contradiction:

Improvespindle support reliabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention maintains spindle support reliability without additional bearings by inverting the insertion method. The recessed portion enables tilted insertion from the inner side, allowing the original load bearings to adequately support the spindle end portions, thus avoiding additional component costs while maintaining structural integrity.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS9132801B2Seat belt retractor and method for assembling spindle of seat belt retractor

Publication Date: 2015.09.15 AUTOLIV DEV AB

AI summary

A seatbelt retractor and method of incorporating a spindle into a retractor frame. The seatbelt retractor includes a spindle having a recessed portion in a cylindrical surface for retracting a webbing, and a retractor frame including two flat plate-shaped side walls that are provided in parallel via an interval (A) in order to support the spindle, each of the two side walls being provided with a circular through hole having a diameter (C). An element on a first end of the spindle is contained within a range of a distance (D) from a deepest portion of the recessed portion, and an element on a second end of the spindle is contained within a range of a distance (B) from the deepest portion of the recessed portion. The distance (D) is smaller than the height (C), and the distance (B) is smaller than the interval (A).