Steering Shaft Anti-Pull Stake for Low-Drag Telescope Motion

Solution Overview

Problem

The existing steering column assemblies with angled stakes create interference conditions that increase stroke efforts and drag, making it desirable to inhibit this interference without affecting the stroke efforts.

Innovation Solution

A steering shaft assembly with an outer shaft having an internally splined portion with fine teeth and an inner shaft that telescopes within it, featuring a stake that axially extends into the outer shaft to resist axial separation loads while minimizing axial distortion, thereby preventing interference without increasing stroke efforts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If angled stakes are used to prevent shaft removal, then the shafts are secured against separation, but interference conditions increase stroke efforts and drag

Engineering Contradiction:

Improveshaft connection stabilityVSAvoidstroke effort

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The stake is divided into multiple segments or teeth that can independently engage with corresponding features on the shaft. This segmentation allows the stake to provide anti-pull functionality through distributed engagement points rather than a single rigid angled stake, reducing interference and stroke effort while maintaining connection stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of using angled stakes that protrude outward to prevent removal, the invention uses stakes that extend axially inward and engage with splined portions. This inverted approach achieves the same anti-pull function while eliminating the interference conditions created by outward-protruding angled stakes, thereby reducing drag and stroke effort.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If stakes are used to prevent shaft separation, then the shafts are secured, but interference conditions create drag

Engineering Contradiction:

Improveshaft connection stabilityVSAvoiddrag

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The stake is divided into multiple segments or teeth that can independently engage with corresponding features on the shaft. This segmentation allows the stake to provide anti-pull functionality through distributed engagement points rather than a single rigid angled stake, reducing interference and stroke effort while maintaining connection stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of using angled stakes that protrude outward to prevent removal, the invention uses stakes that extend axially inward and engage with splined portions. This inverted approach achieves the same anti-pull function while eliminating the interference conditions created by outward-protruding angled stakes, thereby reducing drag and stroke effort.

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If a stake extends into the outer shaft to resist axial separation, then the shafts are secured against pulling apart, but axial distortion may occur

Engineering Contradiction:

Improveshaft connection stabilityVSAvoidshaft structural integrity

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The stake is divided into multiple segments or teeth that distribute the axial separation load across multiple engagement points rather than concentrating stress at a single location. This segmentation reduces localized axial distortion while maintaining the overall anti-pull function, preserving both connection stability and shaft structural integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The stake design incorporates flexibility or dynamic engagement characteristics that allow it to accommodate minor axial movements and distortions without failing. This dynamic approach enables the stake to maintain engagement and resist axial separation while tolerating the natural flexibility and minor distortions of the shaft structure under load.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11421728B2Steering shaft assembly having anti-pull apart feature

Publication Date: 2022.08.23 STEERING SOLUTIONS IP HOLDING CORP

AI summary

A method of manufacturing a steering shaft assembly includes inserting an inner shaft into an outer shaft along a longitudinal axis. The method further includes placing the inner shaft and the outer shaft into a tool having a staking tool provided with a staking feature; aligning a stake with a base of a tooth of the plurality of fine teeth of the outer shaft; and pressing the stake axially into an outer shaft first end to a predetermined depth using the staking feature.