Electric Power Steering Travel Stop Assembly

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Solution Overview

Problem

Steering by wire systems without mechanical connections face issues where the steering wheel can easily rotate beyond the end stops when the vehicle is powered down, leading to potential damage or unsafe conditions.

Innovation Solution

An electric power steering column assembly with a travel stop assembly that includes a screw member and a recessed end plate, which engages the steering shaft to inhibit rotation and prevent over-rotation by using threaded engagements and inclined surfaces to securely stop the steering shaft at predetermined angles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If a steer-by-wire system without mechanical connection is used, then the steering system achieves electrical control and feedback capability, but the steering wheel can easily rotate beyond the end stops when the vehicle is powered down

Engineering Contradiction:

Improveelectrical controlVSAvoidsteering wheel position control

Core Design Contradiction:

Extent of automationVSReliability

Solution Approach 1:

A travel stop assembly is introduced as an intermediary mechanical component between the steering shaft and the environment. This assembly includes a travel stop member with a spherical outer surface that engages with a corresponding recess in the steering shaft, providing physical end stops that prevent over-rotation when electrical power is unavailable.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The steering column is segmented into distinct functional components: the steering shaft, the travel stop assembly, and the spherical engagement mechanism. This segmentation allows the travel stop assembly to independently provide mechanical positioning without interfering with the electrical steering control system.

Inventive Principle:

Principle #1Segmentation

2Extent of automation

If no mechanical connection is provided between steering wheel and steering gear, then the system achieves steer-by-wire functionality, but the steering shaft lacks physical constraints and can rotate freely

Engineering Contradiction:

Improvesteer-by-wire functionalityVSAvoidsteering shaft position limitation

Core Design Contradiction:

Extent of automationVSEase of operation

Solution Approach 1:

The travel stop assembly serves as a passive mechanical intermediary that provides physical constraints to the steering shaft. The spherical outer surface of the travel stop member engages with the recess in the steering shaft, creating definite mechanical end stops that guide the steering shaft rotation within safe limits.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The travel stop assembly is pre-configured with the spherical engagement geometry before operation. The spherical outer surface and corresponding recess are designed in advance to provide automatic mechanical positioning and limiting of steering shaft rotation without requiring active control or adjustment during operation.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10160477B2Electric power steering column assembly

Publication Date: 2018.12.25 STEERING SOLUTIONS IP HOLDING CORP

AI summary

An electric power steering column assembly includes a steering shaft and a travel stop assembly. The steering shaft has a first end that is configured to attach to a steering wheel. The steering shaft has a second end that extends through a steering actuator. The travel stop assembly engages the second end of the steering shaft. The travel stop assembly is configured to inhibit rotation of the steering shaft.