Gas Spring Thermal Release Valve for Stem Expulsion Prevention

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Solution Overview

Problem

Existing air springs in vehicles can explosively expel the piston and stem due to increased external temperatures, posing a safety risk from potential damage caused by the rapid movement of the stem.

Innovation Solution

A safety device with a seal element and a meltable holding mechanism that allows gas to escape when the environmental temperature exceeds a set threshold, preventing overpressure and stem expulsion, utilizing a seal element held in a cylinder hole by a sealing device that changes force based on temperature, featuring a meltable material to control the release.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the gas spring maintains a sealed cylinder chamber to keep gas under pressure, then the dampening effect is ensured, but the risk of explosive stem expulsion increases when external temperature rises

Engineering Contradiction:
Improvedampening effectVSAvoidstem expulsion risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A safety valve is introduced as an intermediary component between the sealed cylinder chamber and the external environment. This valve remains closed during normal operation to maintain gas pressure for dampening, but automatically opens when external temperature exceeds a predetermined threshold, allowing controlled gas release to prevent explosive stem expulsion.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The safety valve utilizes temperature parameter changes to trigger its operation. When the external temperature reaches a predetermined threshold, the valve's physical or chemical properties change (such as thermal expansion, phase change, or material softening), causing it to automatically open and release gas, thereby converting the temperature parameter change into a safety response.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If a safety valve is added to prevent stem expulsion at high temperatures, then safety is improved, but device complexity increases

Engineering Contradiction:
Improvestem expulsion preventionVSAvoidcylinder chamber structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The safety valve is designed as a simple, inexpensive component that can be easily integrated into the cylinder chamber. It uses basic materials such as thermally responsive wax, shape memory alloys, or simple thermal expansion mechanisms rather than complex electronic sensors or actuators, minimizing added complexity while effectively preventing stem expulsion.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The safety valve is designed to operate automatically without external control or power supply. It uses passive thermal response mechanisms where the valve itself reacts to temperature changes through material properties (thermal expansion, phase change, or shape memory effects), eliminating the need for complex control systems, sensors, or power sources.

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

Effectively prevents sudden stem expulsion by allowing controlled gas release at elevated temperatures, enhancing safety without substantial structural changes to existing air springs, ensuring reliable operation and precise temperature control.

Implementation Method 1

a meltable holding means (25) configured to change the sealing force of the sealing device (13) when the temperature of the environment on the outside of the gas spring (1) reaches a pre-set level

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 2

a seal element (11) configured to be inserted, in a sealing manner, in a hole (12) made in the cylinder (2)

Methodology Applied
Scientific EffectSealing:

Implementation Method 3

a gas under pressure contained in the chamber and compressed or expanded depending on the movements of the piston

Methodology Applied
Scientific EffectGas pressure: Pressure Increase

Data Source

PatentEP3521653B1Gas spring comprising a safety device
Publication Date: 2022.01.12 IVECO SPA
  • EP3521653B1 patent drawingFigure 1
  • EP3521653B1 patent drawingFigure 2~5
  • EP3521653B1 patent drawingFigure 6~7

AI summary

A gas spring (1) for a vehicle comprising a cylinder (2) and a piston (3) adapted to slide in the cylinder, the cylinder (2) and the piston (3) defining a chamber (5) between one another, adapted to contain the gas under pressure, the gas spring (1) also comprises a safety device (10) configured to allow the outflow of the gas under pressure from the chamber (5) when the environmental temperature around the gas spring (1) reaches a pre-set temperature.