Torque Transmission Joint With Backup Engagement for Steering Continuity

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Solution Overview

Problem

Conventional torque transmission joints in electric power steering devices face issues with maintaining continuous torque transmission between end section transmission members when the torque transmission function of the intermediate transmission member deteriorates.

Innovation Solution

The torque transmission joint incorporates an intermediate transmission member with an intermediate concave-convex section and a pair of end section transmission members, featuring preliminary engagement sections that adjust their engagement based on the condition of the intermediate transmission member's function, allowing for continuous torque transmission by altering the engagement gaps between the members.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the torque transmission function of the intermediate transmission member deteriorates, then the torque transmission between end section transmission members is interrupted, but adding preliminary engagement sections increases device complexity

Engineering Contradiction:
Improvecontinuous torque transmissionVSAvoidjoint structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The preliminary engagement sections are designed to engage before the main concave-convex sections, creating a backup torque transmission path. When the intermediate transmission member's function deteriorates, the preliminary engagement sections continue to transmit torque, ensuring continuous operation without requiring complex alternative transmission systems.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The preliminary engagement sections act as an intermediary torque transmission path between the end section transmission members. This intermediary path engages through the elastic member and maintains torque transmission even when the primary path through the intermediate transmission member's concave-convex sections fails.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the engagement between end section transmission members is maintained through the intermediate transmission member, then misalignment tolerance is reduced, but allowing pivotal displacement increases misalignment tolerance

Engineering Contradiction:
Improvemisalignment toleranceVSAvoidtorque transmission continuity
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The joint allows dynamic adjustment of the engagement state between end section transmission members. The elastic member enables the preliminary engagement sections to maintain contact while accommodating pivotal displacements and misalignments, providing both adaptability and reliable torque transmission continuity.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The engagement force and gap parameters between the preliminary engagement sections are designed to change based on the operational state. When misalignment occurs, the elastic member deforms to maintain engagement, automatically adjusting the transmission parameters to preserve both misalignment tolerance and torque transmission reliability.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3660346B1Torque transmission joint and electric power steering device
Publication Date: 2022.04.13 NSK LTD
  • EP3660346B1 patent drawingFigure 1
  • EP3660346B1 patent drawingFigure 2
  • EP3660346B1 patent drawingFigure 3

AI summary

Provided is a torque transmission joint that makes it possible to transmitting torque continuously between a pair of end section transmission members even when the torque transmission function of an intermediate transmission member is deteriorated. The torque transmission joint includes an intermediate transmission member 19, and a first transmission member 17 and a second transmission member 18 that are arranged with one each on both side sections in the axial direction of the intermediate transmission member 19, with the outer side sections in the radial direction of each engaging with the inside section in the radial direction of the intermediate transmission member 19. The first transmission member 17 and the second transmission member 18 have a first preliminary engagement section 63 and a second preliminary engagement section 66 at the end sections in the axial direction on sides close to each other. The first preliminary engagement section 63 and the second preliminary engagement section 66 engage with each other with a circumferential gap interposed therebetween that does not disappear when torque transmission is performed between the first transmission member 17 and the second transmission member 18 via the intermediate transmission member 19.