Rod-Shaped Knee Protector for Vehicle Dash Panel Assembly

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Solution Overview

Problem

In motor vehicle collisions, existing switch panel arrangements can intrude excessively when an unbelted occupant is involved, potentially detuning the knee airbag system due to excessive yielding.

Innovation Solution

A dash panel assembly with a transversely extending cross member and rod-shaped knee protectors fastened to it, featuring a force-absorbing section that absorbs loads along its axis, preventing transverse forces and maintaining the knee airbag system's effectiveness by minimizing panel intrusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the dash panel is designed to yield in the event of a collision, then energy absorption is improved, but the panel intrudes excessively into the occupant space when an unbelted occupant is involved

Engineering Contradiction:

Improveenergy absorptionVSAvoidpanel intrusion

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The knee protector is divided into distinct functional sections: a force-absorbing section with deformation capability for energy absorption, and a support section with higher stiffness for maintaining structural integrity and preventing excessive panel intrusion. This segmentation allows different parts of the same component to fulfill conflicting requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the knee protector have different mechanical properties: the force-absorbing section is designed to deform and absorb energy, while the support section maintains higher stiffness to prevent excessive intrusion. This local differentiation of material or structural properties resolves the contradiction between energy absorption and intrusion prevention.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If the knee protector is designed to be stiff to prevent panel intrusion, then occupant protection is improved, but transverse forces are transmitted to the airbag system causing detuning

Engineering Contradiction:

Improvepanel intrusion preventionVSAvoidairbag system performance

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The knee protector is segmented into a force-absorbing section that handles axial loads and a support section that provides transverse stability. This segmentation allows the structure to be stiff where needed for intrusion prevention while remaining compliant in the axial direction to avoid transmitting harmful transverse forces to the airbag system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of making the entire knee protector stiff to prevent intrusion, the invention inverts the approach by making only the necessary support section stiff while allowing the force-absorbing section to be compliant. This selective stiffness distribution prevents both excessive intrusion and airbag detuning.

Inventive Principle:

Principle #13The other way round (Inversion)

3Loss of energy

If deformation means are provided in the knee protector, then energy absorption is improved, but the component complexity increases

Engineering Contradiction:

Improveenergy absorptionVSAvoidknee protector structure

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The force-absorbing section and support section are merged into a single integrated knee protector component, eliminating the need for separate deformation elements and simplifying the overall structure while maintaining energy absorption capabilities through the designed force-absorbing section.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The knee protector utilizes changes in geometric parameters along its length to create different functional zones: the force-absorbing section has parameters optimized for deformation and energy absorption, while the support section has parameters optimized for stiffness and stability, achieving complex functionality through parameter variation rather than structural complexity.

Inventive Principle:

Principle #35Parameter changes

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 solution effectively reduces the intrusion of the dash panel during collisions with unbelted occupants, ensuring the knee airbag system remains functional by absorbing forces along the axis of the knee protector, thereby maintaining its integrity and functionality.

Implementation Method 1

each having a force absorbing section (21) which is designed to absorb forces essentially in the direction of travel

Methodology Applied

Scientific EffectDeformation: Deformation

Data Source

PatentEP2020342B1Instrument panel assembly for a motor vehicle

Publication Date: 2012.01.25 DR ING H C F PORSCHE AG

Figure 1
Figure 2~3
Figure 4

AI summary

The arrangement has a cross beam (13) extending transverse to a vehicle longitudinal direction, and held at two firm lateral installation structures (3, 4). A knee bolster (12) has a fastening section for fastening the knee bolster to the cross beam. The fastening section has a force receiving section extending in the direction of the knee of a passenger. The force receiving section is a rod-shaped carrying element, which is loaded lengthwise to an axis. The fastening section has an internal contour that is formed at a connecting element (23) of the cross beam.