Spherical Coupling for Electric Power Steering Misalignment

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Solution Overview

Problem

Current coupling designs in electric power steering systems for motor vehicles suffer from radial force transmission, misalignment issues, and complex assembly processes, leading to noise amplification and potential incorrect assembly due to the use of multiple flanges with branches.

Innovation Solution

A coupling device featuring two flanges with diametrically opposed spherical heads and a disc-shaped coupling part with corresponding grooves, allowing for greater misalignment and angle acceptance without radial force transmission, and simplified assembly through axial splines and central fixing screws.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If flanges with three or four branches are used to accept misalignment and orientation tolerances, then adaptability is improved, but radial forces are transmitted and noise is amplified

Engineering Contradiction:
Improvemisalignment acceptanceVSAvoidradial forces and noise
Core Design Contradiction:
Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent uses spherical heads on the flange branches that engage with corresponding spherical sockets in the coupling element. This spherical geometry allows the branches to pivot and accommodate misalignment and orientation tolerances while maintaining point contact, thereby avoiding the transmission of radial forces that would occur with rigid flat surface contacts.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Adaptability or versatility

If multiple flanges with branches are used, then misalignment tolerance is accepted, but device complexity increases

Engineering Contradiction:
Improveaxis orientation acceptanceVSAvoidnumber of flanges and branches
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the functions of multiple flanges with branches into a single integrated coupling element. This coupling element has a central body with multiple spherical sockets arranged to accept branches from different orientations, thereby accommodating misalignment and orientation tolerances while reducing the total number of separate components.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of operation

If flexible coupling elements are mounted between flanges, then assembly flexibility is improved, but assembly complexity increases

Engineering Contradiction:
Improveassembly flexibilityVSAvoidassembly operations
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent introduces a coupling element as an intermediary component that features a central body with multiple spherical sockets. This intermediary piece receives branches from multiple flanges simultaneously, acting as a mediator that simplifies the assembly process by providing a single mounting point for multiple connections rather than requiring sequential assembly of multiple flange pairs.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP2532908B1Clutch device between a motor and a gear train assembly in an automotive electric power steering device
Publication Date: 2014.06.11 JTEKT EUROPE SAS
  • EP2532908B1 patent drawingFigure 1~5
  • EP2532908B1 patent drawingFigure 6~10
  • EP2532908B1 patent drawingFigure 11~16

AI summary

The device (8) provides a coupling between the shaft (7) of the electric assist motor (2) and a worm gear (4) constituting the input shaft of the gearbox (3). Two flanges (9, 10), each having two diametrically opposed spherical heads (12, 15), are mounted opposite each other, respectively on the shaft (7) of the electric motor and on the end (17) of the worm gear. Between the two flanges is inserted a disc-shaped coupling piece (11), having on each of its faces two diametrically opposed spherical grooves (18, 20) that house the spherical heads of the two flanges, the grooves (18) of one face being arranged with a diameter perpendicular to the grooves (20) of the other face.