Force Limiting Device with Wave-Like Feed Movement

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Solution Overview

Problem

Existing force-limiting devices in motor vehicles, such as those using torsion bars, require additional mass systems to achieve frequency-controlled movement, leading to increased weight and size, limiting the ability to absorb large forces effectively.

Innovation Solution

The implementation of interlocking teeth on moving parts that execute a wave-like feed movement, eliminating the need for a separate mass system, allowing for energy dissipation through alternating engagement and disengagement, and potentially incorporating a planetary gear to adjust force limitation levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a separate mass system is used to achieve frequency-controlled movement, then the force limitation level can be adjusted, but the device weight and size increase

Engineering Contradiction:
Improveforce limitation level adjustmentVSAvoiddevice weight
Core Design Contradiction:
Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The invention merges the mass system function with the force-limiting device structure itself. The housing and moving parts of the force-limiting device serve dual purposes: they both limit force through their structural design and provide the mass necessary for frequency-controlled movement. This eliminates the need for a separate mass system, resolving the contradiction between adaptability and weight.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The force-limiting device structure is designed to perform multiple functions simultaneously. The housing and internal components serve both as the force-limiting mechanism and as the mass system required for frequency control. This multi-functionality allows the device to achieve adjustable force limitation levels without adding extra weight from separate mass components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If a separate mass system is used to achieve frequency-controlled movement, then the force limitation level can be adjusted, but the device size increases

Engineering Contradiction:
Improveforce limitation level adjustmentVSAvoiddevice size
Core Design Contradiction:
Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The invention merges the mass system function with the force-limiting device structure itself. The housing and moving parts of the force-limiting device serve dual purposes: they both limit force through their structural design and provide the mass necessary for frequency-controlled movement. This eliminates the need for a separate mass system, resolving the contradiction between adaptability and weight.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The force-limiting device structure is designed to perform multiple functions simultaneously. The housing and internal components serve both as the force-limiting mechanism and as the mass system required for frequency control. This multi-functionality allows the device to achieve adjustable force limitation levels without adding extra weight from separate mass components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Loss of energy

If the moving part has high mass for energy dissipation, then a large amount of energy can be absorbed, but the device weight increases

Engineering Contradiction:
Improveenergy absorptionVSAvoiddevice weight
Core Design Contradiction:
Loss of energyVSWeight of moving object

Solution Approach 1:

The invention merges the mass system function with the force-limiting device structure itself. The housing and moving parts of the force-limiting device serve dual purposes: they both limit force through their structural design and provide the mass necessary for frequency-controlled movement. This eliminates the need for a separate mass system, resolving the contradiction between adaptability and weight.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The force-limiting device uses its own structural mass for energy dissipation rather than requiring an external mass system. The housing and internal components that are already present for force limitation purposes also serve as the mass that absorbs energy during operation, making the system self-sufficient and eliminating unnecessary weight.

Inventive Principle:
Principle #25Self-service

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

This solution enables a higher level of force limitation with reduced device weight or size, increased energy absorption, and adaptability to different force limitation levels by utilizing the moving part's mass for energy dissipation, while maintaining a compact design.

Implementation Method 1

The energy is dissipated by the parts being alternately decelerated and accelerated

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

the teeth alternately engage and disengage

Methodology Applied
Scientific EffectImpact Force: Impact Force

Implementation Method 3

The energy is dissipated by the parts being alternately decelerated and accelerated, with the frequency being almost independent of the acting force

Methodology Applied
Scientific EffectInertia: Inertia

Implementation Method 4

a mass system that is set in motion at a predetermined frequency

Methodology Applied
Scientific EffectVibration: Vibration

Data Source

PatentEP2342100B1Force limiting device for a motor vehicle
Publication Date: 2016.01.13 AUTOLIV DEV AB
  • EP2342100B1 patent drawingFigure 1a~1d
  • EP2342100B1 patent drawingFigure 2
  • EP2342100B1 patent drawingFigure 3

AI summary

The invention relates to a force limiting device for a motor vehicle, comprising at least two parts (1, 2, 10, 12, 16, 20, 21, 46, 22, 40) controlled in relation to each other by a movement defined according to frequency. The parts (1, 2, 10, 12, 16, 20, 21, 46, 22, 40) moving in relation to each other comprise toothings (3, 4, 13, 15, 24, 25, 26, 27) which engage in each other and the movement controlled according to frequency takes place in such a way that at least one of the parts (1, 10, 21, 22) performs an undulating advancing movement in relation to the other part (2, 12, 16, 20, 40, 46), by which means the toothings (3, 4, 13,1 5, 24, 25, 26, 27) alternately engage and disengage.