Integrated Steering Rack Subframe Structure

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Solution Overview

Problem

Existing subframe structures in vehicles experience stress concentration at fastening/fixation sites, which hinders rigidity and strength, and require additional reinforcement members, increasing weight and complexity, particularly in achieving collision safety performance.

Innovation Solution

The subframe structure integrates the steering rack mechanism's outer tubular portion with the subframe, eliminating the need for fastening/fixation sites and enhancing rigidity and strength by forming a unified structure that reduces stress concentration and improves load transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the steering rack is fastened to the subframe using fastening parts, then the steering rack can be securely fixed, but stress concentrates at the fastening sites which reduces rigidity and strength

Engineering Contradiction:

Improverigidity and strength of steering rackVSAvoidstress concentration at fastening sites

Core Design Contradiction:

StrengthVSStress or pressure

Solution Approach 1:

The outer tubular portion of the steering rack and the subframe are integrally formed as a single piece, eliminating the fastening parts that cause stress concentration. This merging of previously separate components resolves the contradiction by providing secure fixation without stress concentration points.

Inventive Principle:

Principle #5Merging (Combining)

2Strength

If reinforcement members such as stiffeners are added to improve rigidity and strength, then collision safety performance improves, but vehicle weight increases

Engineering Contradiction:

Improverigidity and strength for collision safetyVSAvoidvehicle weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The integral formation of the outer tubular portion and subframe creates a unified load-bearing structure that provides the necessary rigidity and strength for collision safety without requiring additional reinforcement members, thereby avoiding weight increase.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated structure serves multiple functions simultaneously: it provides structural support, load transmission, and collision safety reinforcement, eliminating the need for separate reinforcement members that would add weight.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If additional fastening parts and reinforcement members are used, then fixation reliability improves, but device complexity increases

Engineering Contradiction:

Improvefixation reliability of steering rackVSAvoidcomplexity of fastening and reinforcement structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

By integrating the outer tubular portion and subframe into a single component, the invention eliminates multiple fastening parts and reinforcement members, thereby reducing device complexity while maintaining fixation reliability through the integral structure.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS20240109589A1Subframe structure

Publication Date: 2024.04.04 HONDA MOTOR CO LTD

AI summary

In a subframe structure in a vehicle including a steering rack mechanism and a subframe structure body having a plurality of fixation portions fixed to a vehicle body, the steering rack mechanism has an outer tubular portion extending in a vehicle width direction, and the subframe main body and the outer tubular portion are integrally formed.