Steering Device Slip Ring Stabilizes Torque

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Solution Overview

Problem

Conventional steering lock mechanisms face challenges in maintaining dimensional accuracy and stability of slip torque, leading to increased machining costs due to strict management requirements and sensitivity to fastening margin changes, which affects the slip ring's spring constant and residual stress.

Innovation Solution

A steering apparatus with a cylindrical slip ring interposed between the steering shaft and key lock collar, featuring protruded portions and large- and small-diameter portions to absorb dimensional errors and reduce load changes, allowing for increased dimensional allowance and improved workability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a non-contact portion is formed between the steering shaft and key lock collar to acquire stable slip torque, then slip torque stability is improved, but dimensional accuracy management becomes strict and machining cost rises

Engineering Contradiction:
Improveslip torque stabilityVSAvoiddimensional accuracy management
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

A slip ring is introduced as an intermediary component between the steering shaft and key lock collar. The slip ring includes a large-diameter portion that contacts the steering shaft and a small-diameter portion that contacts the key lock collar, creating a tapered interface that absorbs dimensional variations and stabilizes slip torque without requiring strict dimensional control of the shaft-collaar interface

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The slip ring changes the geometric parameters of the interface by incorporating a tapered structure (large-diameter to small-diameter transition). This parameter change allows the interface to accommodate dimensional variations while maintaining stable slip torque characteristics

Inventive Principle:
Principle #35Parameter changes

2Reliability

If a slip ring is attached to the fitting portion between key lock collar and steering shaft to protect the mechanism, then protection function is improved, but dimensional accuracy management becomes strict and machining cost rises due to sensitivity to fastening margin changes

Engineering Contradiction:
Improvemechanism protectionVSAvoiddimensional accuracy management
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The slip ring serves as a protective intermediary component that absorbs dimensional errors and reduces sensitivity to fastening margin variations. The tapered geometry (large-diameter and small-diameter portions) creates a self-aligning interface that compensates for manufacturing tolerances

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The slip ring provides beforehand cushioning by absorbing dimensional errors and fastening margin variations before they can affect the locking mechanism's operation. The elastic or compliant nature of the slip ring allows it to accommodate variations without transmitting them to the critical locking components

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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

The configuration stabilizes slip torque and enlarges the range of dimensional allowance, reducing machining costs and ensuring stable and smooth rotation without being caught, while maintaining effective locking functionality.

Implementation Method 1

a cylindrical slip ring being interposed between the steering shaft and the key lock collar in radial directions, in which the steering shaft takes a shape to reduce a change in load against displacement (a quantity of deformation in the radial directions)

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP2923900B1Steering device
Publication Date: 2017.05.24 NSK LTD
  • EP2923900B1 patent drawingFigure 1
  • EP2923900B1 patent drawingFigure 2
  • EP2923900B1 patent drawingFigure 3A~3B

AI summary

A steering apparatus includes a key lock collar (5) fitted on a steering shaft (2) and restricted from rotating by a steering lock mechanism when performing a steering lock, and a cylindrical slip ring (7) interposed between the steering shaft (2) and the key lock collar (5) in radial directions. The slip ring (7) includes a plurality of protruded portions (8) protruding outwardly or inwardly in the radial directions and being provided in a circumferential direction, and an axis-directional portion of the steering shaft (2) covered by the slip ring (7) is formed with a large-diameter portion (10a) and a small-diameter portion (10b), thereby further stabilizing slip torque of the key lock collar (5) and enlarging a range of a dimensional allowance.