Vehicle Subframe X-Cross Geometry for Torsional Load Management

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Solution Overview

Problem

Existing subframes for vehicles do not effectively manage varying loads and stresses, leading to inadequate fatigue life and structural integrity, particularly under torsional and lateral forces.

Innovation Solution

A subframe design featuring two longitudinal beams with front and rear X-cross arrangements, where connecting members in the front X-cross arrangement are angled differently from those in the rear, creating a gradual reduction in stiffness from the rear to the front, enhanced by plate-like stiffeners and transverse support elements, optimizing the structure for lateral and torsional loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If uniform X-cross arrangements are used throughout the subframe, then manufacturing is simplified, but the subframe cannot effectively manage varying loads and stresses

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidfatigue life
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies different angles to connecting members in different regions of the subframe. The front X-cross arrangement uses connecting members at a first angle while the rear X-cross arrangement uses connecting members at a second angle, optimizing each region for its specific load requirements rather than using a uniform design throughout.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The subframe is divided into distinct sections with different X-cross arrangement configurations. The front and rear portions have different connecting member angles, allowing each segment to be optimized for local stress patterns while maintaining overall structural integrity.

Inventive Principle:
Principle #1Segmentation

2Strength

If the subframe is made stronger to handle torsional and lateral loads, then structural integrity improves, but the complexity of the structure increases

Engineering Contradiction:
Improvestructural strengthVSAvoidstructural complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent changes the geometric parameters of the connecting members by using different angles in different regions. This parameter variation allows the structure to achieve optimal strength characteristics for handling torsional and lateral loads without requiring additional complex components or reinforcement elements.

Inventive Principle:
Principle #35Parameter changes

3Strength

If additional welds are added to strengthen the subframe, then structural strength improves, but the fatigue life at weld locations deteriorates

Engineering Contradiction:
Improvestructural strengthVSAvoidfatigue life at welds
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The optimized connecting member angles create a more efficient stress distribution pattern that reduces concentrated stresses at weld locations. This local optimization of the structural configuration allows the subframe to achieve sufficient strength without requiring excessive welds that would compromise fatigue life.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4596372A1Subframe for vehicle, and vehicle
Publication Date: 2025.08.06 SSAB TECHNOLOGY AB
  • EP4596372A1 patent drawingFigure 1
  • EP4596372A1 patent drawingFigure 2
  • EP4596372A1 patent drawingFigure 3

AI summary

A subframe (100) for a vehicle and a vehicle. The subframe comprises two longitudinal beams (1a, 1b) arranged in the lengthwise direction (X) of the vehicle, a front X-cross arrangement (2) and a rear X-cross arrangement (3). Said X-cross arrangements (2, 3) are arranged between the two longitudinal beams (1a, 1b). Each of the front and rear X-cross arrangements (2, 3) comprises connecting members (4f, 4r) arranged crosswise and diagonally in relation to the lengthwise direction (X) for connecting the longitudinal beams (1a, 1b) such that an X-shape is created. The connecting members (4f, 4r) in the front X-cross arrangement (2) are arranged in another angle compared to the connecting members (4f, 4r) in the rear X-cross arrangement (3), such that the front X-cross arrangement (2) is shorter than the rear X-cross arrangement (3) in the lengthwise direction (X).