Steering Device Rotation Restriction Mechanism

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Solution Overview

Problem

Existing steering devices face challenges in maintaining rotation restriction of the inner column during excessive torque loads without compromising the contraction operation of the steering column upon a secondary collision, which can lead to theft and adverse effects on energy absorption performance.

Innovation Solution

A steering device with a rotation restriction mechanism that includes a support shaft, a restriction member, and an urging member, where the restriction member is displaced between an inserted and retracted position to engage with rotation restricted edge portions, securing the inner tube's rotation and allowing contraction during secondary collisions without hindering the steering column's absorption performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a rotation restriction mechanism is provided to restrict rotation of the inner column, then the keylock device function is improved, but the contraction operation of the steering column upon secondary collision is hindered

Engineering Contradiction:

Improvekeylock device functionVSAvoidcontraction operation

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The rotation restriction mechanism is designed to dynamically change its state based on collision conditions. The restriction member can rotate relative to the support shaft, allowing it to engage with rotation restricted edge portions during normal operation to prevent rotation, while being capable of disengaging during secondary collision to allow contraction movement. This dynamic behavior resolves the contradiction between maintaining rotation restriction and enabling collision contraction.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The mechanism changes the engagement parameter between the restriction member and the opening. During normal operation, the restriction member engages with the rotation restricted edge portions to restrict rotation. During secondary collision, the relative movement between the inner tube and outer tube causes the restriction member to disengage from the rotation restricted edge portions, allowing the contraction operation to proceed without hindrance.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the restriction member is fixed to restrict rotation, then rotation restriction is improved, but the steering column cannot absorb energy during secondary collision

Engineering Contradiction:

Improverotation restrictionVSAvoidenergy absorption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The restriction member is designed with rotational freedom relative to the support shaft, enabling it to dynamically adjust its engagement state. During normal operation, it maintains engagement with rotation restricted edge portions to provide rotation restriction. During secondary collision, the inner tube's movement causes the restriction member to rotate and disengage, allowing the steering column to contract and absorb collision energy effectively.

Inventive Principle:

Principle #15Dynamics

3Reliability

If the restriction member engages with rotation restricted edge portions, then rotation of inner tube is prevented, but contraction movement is blocked

Engineering Contradiction:

Improverotation preventionVSAvoidcontraction movement

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The opening is designed with different functional regions: rotation restricted edge portions that engage with the restriction member to prevent rotation, and a driving edge portion that engages with the restriction member to enable contraction movement. This local differentiation of functional qualities allows the mechanism to selectively enable rotation prevention or contraction based on operational conditions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The restriction member can dynamically switch between engaging with rotation restricted edge portions (for rotation prevention) and being driven by the driving edge portion (for contraction movement). The relative movement between the inner tube and outer tube during secondary collision causes this dynamic switching of engagement targets.

Inventive Principle:

Principle #15Dynamics

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 solution effectively restricts rotation of the inner tube under torque loads, preventing theft and ensuring stable shock absorption by allowing the steering column to contract during secondary collisions without affecting its energy absorption capabilities.

Implementation Method 1

an urging member that urges the restriction member toward the inserted position

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The driving edge portion is configured to drive the restriction member toward the retracted position via the driven portion upon the secondary collision

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentUS9381935B2Steering device

Publication Date: 2016.07.05 JTEKT CORP

AI summary

In a steering device, a restriction member urged by an urging member restricts rotation of an inner tube when the restriction member is at an inserted position at which the restriction member is inserted into a second opening of the inner tube through a first opening of an outer tube. When the inner tube moves to contract a steering column upon a secondary collision, a driving edge portion of the second opening drives the restriction member to a position at which the restriction member is retracted from the second opening against the urging member.