Bendable Combustion Chamber Bottom for Hybrid Inflator Gas Discharge

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Solution Overview

Problem

Existing hybrid inflators for automotive airbag systems have complex constructions with many components and seals, making them costly and prone to faults, and lack an efficient mechanism for controlled discharge of compressed gas into the airbag.

Innovation Solution

A combustion chamber with a sleeve-type design and a bendable bottom that includes an integrated opening device, eliminating the need for movable components, where the combustion chamber bottom bends to open the compressed gas tank membrane, allowing controlled discharge of gas into the airbag module.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a piston-type device with guiding supports and seals is used to open the compressed gas tank, then the opening function can be achieved, but the device complexity increases and manufacturing costs rise

Engineering Contradiction:

Improveopening functionVSAvoidconstruction complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The combustion chamber bottom is merged with the opening device to form an integrated structure. The bottom itself performs the opening function by bending and piercing the membrane, eliminating the need for separate piston, supports, and seals. This merging of functions directly reduces device complexity while maintaining the opening capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The complex piston-type opening mechanism (including piston, guiding supports, and seals) is extracted and removed from the system. Instead, a simplified combustion chamber bottom design is used that inherently performs the opening function through its bending motion, thereby reducing component count and complexity.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If a piston-type device with multiple components is used to open the compressed gas tank, then the opening function can be achieved, but manufacturing efforts and costs increase

Engineering Contradiction:

Improveopening functionVSAvoidmanufacturing effort

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The opening device is merged into the combustion chamber bottom as an integral structure. This single-piece design eliminates the need to manufacture and assemble multiple separate components (piston, supports, seals), significantly reducing manufacturing effort and costs while ensuring reliable operation.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The design uses a simple, inexpensive combustion chamber bottom structure that performs the opening function through controlled bending and piercing. This disposable-like approach replaces expensive, precision-manufactured piston assemblies with a simpler, more cost-effective structure that achieves the same function.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Device complexity

If the combustion chamber bottom is made bendable to open the membrane, then the opening device complexity is reduced, but the structural design becomes more challenging

Engineering Contradiction:

Improveopening device complexityVSAvoidcombustion chamber bottom structure

Core Design Contradiction:

Device complexityVSShape

Solution Approach 1:

The combustion chamber bottom is designed with dynamic characteristics, allowing it to bend and deform during operation to perform the opening function. This dynamic capability enables the bottom to transition from a static structural element to an active opening mechanism, reducing overall device complexity.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The structural parameters of the combustion chamber bottom are optimized to allow controlled bending while maintaining integrity. By adjusting thickness, material properties, and geometric configuration, the bottom achieves the right balance between flexibility for opening and strength for containing combustion pressures.

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

This design simplifies the construction, reduces costs, and enables a controlled and efficient discharge of both cold and hot gases into the airbag, ensuring gentle deployment and weight savings in the hybrid inflator system.

Implementation Method 1

the combustion chamber bottom can be bent in the case of operation

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

a pyrotechnical subassembly, wherein the pyrotechnical subassembly serves for releasing the hybrid inflator and/or heating the gas

Methodology Applied

Scientific EffectPyrotechnical heating: Combustion

Data Source

PatentUS9789845B2Combustion chamber comprising an opening device for a compressed gas tank of a hybrid inflator, hybrid inflator, airbag module, vehicle safety system and method of discharging fluid from an inflator

Publication Date: 2017.10.17 TRW AIRBAG SYSTEMS GMBH

AI summary

The invention relates to a combustion chamber (10) comprising an opening device for a compressed gas tank (21) of a hybrid inflator (20), wherein the combustion chamber (30) comprises a sleeve-type combustion chamber sidewall (34) confining a combustion chamber interior (31) and a combustion chamber bottom (10), wherein the opening device is arranged on a surface (11) of the combustion chamber bottom (10) facing away from the combustion chamber interior (31) and faces away from the combustion chamber interior (31). In accordance with the invention, the combustion chamber bottom (10) is tightly connected to the combustion chamber sidewall (34) so that in the case of operation the combustion chamber bottom (10) is bendable.