Motor Vehicle Subframe Truss Stiffening Element

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Solution Overview

Problem

Existing subframes for motor vehicles face challenges in efficiently absorbing forces during driving and crashes, are heavy, and have limited access for maintenance, with existing stiffening elements being cumbersome and expensive to produce.

Innovation Solution

A subframe with a truss structure stiffening element that allows for adjustable force absorption, easy access to the engine compartment, and reduced weight, featuring predetermined kinks on longitudinal struts for deformation control and removable attachment points for easy maintenance, produced from a sheet metal blank with a high free area for assembly access.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If a flat single-shell stiffening element is used, then good encapsulation of the engine compartment is achieved, but access to the engine compartment from below is difficult and the stiffening element is relatively heavy

Engineering Contradiction:
Improveencapsulation areaVSAvoidaccessibility
Core Design Contradiction:
Area of stationary objectVSEase of operation

Solution Approach 1:

The stiffening element is divided into multiple shell segments (first shell, second shell, third shell, fourth shell) that are arranged to form a truss structure. This segmentation creates free areas between the shells, improving accessibility to the engine compartment from below while maintaining encapsulation through the coordinated arrangement of all shells together.

Inventive Principle:
Principle #1Segmentation

2Stability of the object's composition

If a flat single-shell stiffening element is used, then structural continuity is maintained, but the stiffening element is relatively heavy

Engineering Contradiction:
Improvestructural continuityVSAvoidstiffening element weight
Core Design Contradiction:
Stability of the object's compositionVSWeight of stationary object

Solution Approach 1:

The stiffening element is segmented into multiple shells forming a truss structure with free areas between them. This segmentation reduces material usage and weight while the interconnected arrangement of shells maintains overall structural continuity and stiffness.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The stiffening element uses a composite shell structure where multiple shells are arranged to form a truss configuration. This composite approach provides equivalent or superior structural performance to a solid single-shell element while significantly reducing weight through the spaces between shells.

Inventive Principle:
Principle #40Composite materials

3Area of stationary object

If large wall surfaces are used in the stiffening element, then structural coverage is improved, but the element is prone to booming

Engineering Contradiction:
Improvestructural coverageVSAvoidbooming susceptibility
Core Design Contradiction:
Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The stiffening element is segmented into multiple shells arranged in a truss structure, creating a framework rather than large continuous surfaces. This segmentation maintains structural coverage through the distributed arrangement of shells while eliminating the large wall surfaces that are prone to booming.

Inventive Principle:
Principle #1Segmentation

4Ease of operation

If a truss structure with multiple shells is used, then accessibility and weight are improved, but structural rigidity must be maintained

Engineering Contradiction:
ImproveaccessibilityVSAvoidstructural rigidity
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The stiffening element is segmented into multiple shells forming a truss structure with free areas between them, improving accessibility. The triangular and rectangular configurations of the shell arrangement provide structural rigidity equivalent to solid structures while allowing access through the spaces between shells.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The stiffening element transitions from a two-dimensional flat plate to a three-dimensional truss structure with shells arranged in multiple layers and orientations. This dimensional change creates free areas for accessibility while the spatial configuration of shells maintains structural rigidity through geometric stability.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 subframe offers improved energy absorption during crashes, adjustable deceleration, and cost-effective production with enhanced maintenance accessibility, while maintaining structural rigidity and crash performance.

Implementation Method 1

In the event of a crash, part of the deformation energy can be absorbed by deformation of the subframe

Methodology Applied
Scientific EffectDeformation: Deformation

Implementation Method 2

the subframe according to the invention offers improved energy absorption capacity, particularly in the area of the longitudinal struts

Methodology Applied
Scientific EffectEnergy absorption: Absorption (physical)

Implementation Method 3

Predetermined kinks on the longitudinal struts prevent the subframe from blocking

Methodology Applied
Scientific EffectBuckling:

Implementation Method 4

The course of the force absorption and thus the deceleration course of the vehicle during a deformation of the same can be adjusted well by their design

Methodology Applied
Scientific EffectControlled deformation: Deformation

Data Source

PatentEP2477875B2Support frame for a motor vehicle
Publication Date: 2019.03.06 VOLKSWAGEN AG
  • EP2477875B2 patent drawingFigure 1~2
  • EP2477875B2 patent drawingFigure 3
  • EP2477875B2 patent drawingFigure 4~5

AI summary

The invention relates to a support frame for a motor vehicle, comprising two longitudinal beams (11) and a transverse beam (12) and a single-shell stiffening element (13), which extends between the longitudinal beams (11) of the support frame. The stiffening element (13) has two longitudinal braces (20) and two transverse braces (21), which form a substantially rectangular outer frame. Several inner braces (22) are arranged inside the outer frame in a latticed manner. A predetermined buckling point (26) is formed on each of the longitudinal braces (20) of the stiffening element (13). A support frame is thereby created that can be produced at low cost, has a low component weight, and has favorable mechanical properties both in regard to the absorption of forces during driving operation and in the event of a crash.