Hydrogen Tank Valve Thermal Release Using a Shape-Memory Trigger
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Solution Overview
Problem
Existing multifunction valves for high-pressure hydrogen tanks in automotive fuel cell systems lack an effective thermal safety device that can immediately detect dangerous conditions and initiate gas evacuation under pressure.
Innovation Solution
A multifunction valve equipped with a thermal safety device featuring a breakable bulb and a trigger group with a heat-sensitive element made of shape-memory material, which upon detecting a critical temperature, mechanically activates a hammer to break the bulb, allowing immediate gas evacuation through a bypass and evacuation duct.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal safety device with a breakable bulb is used to detect dangerous temperatures, then the safety response time is improved, but the device complexity increases due to the addition of the hammer and trigger group mechanism
Solution Approach 1:
The hammer is pre-positioned in a retracted state by the trigger group, ready to strike the bulb when needed. The trigger group maintains the hammer in a held position during normal operation, and automatically releases it when the heat-sensitive element detects dangerous temperatures, enabling immediate response without requiring complex real-time control mechanisms
Solution Approach 2:
The heat-sensitive element acts as an intermediary between the temperature detection and the mechanical action. It translates thermal conditions into mechanical movement that triggers the trigger group to release the hammer, providing a simple yet effective coupling between thermal detection and safety activation without requiring complex electronic or mechanical control systems
2Reliability
If the hammer is held in the backward position by the stop during normal operation, then false activation is prevented, but the device complexity increases due to the additional stop component
Solution Approach 1:
The stop is integrated into the trigger group assembly, combining the holding function with the release mechanism. The stop works in conjunction with the heat-sensitive element and hammer to form a unified safety trigger system, reducing the need for separate components and simplifying the overall structure while maintaining reliable false activation prevention
Solution Approach 2:
The trigger group automatically maintains the hammer in the retracted position during normal operation and self-activates when dangerous temperatures are detected. The heat-sensitive element directly triggers the release mechanism without requiring external control systems, sensors, or power sources, eliminating the need for complex control logic while ensuring reliable operation
3Adaptability or versatility
If a shape-memory material wire is used in the heat-sensitive element, then the detection range is extended to include remote temperature increases, but the manufacturing precision requirements increase
Solution Approach 1:
The heat-sensitive element utilizes the phase transition temperature of shape-memory material as a critical parameter. By selecting materials with specific transformation temperatures, the device can be tuned to respond to different temperature thresholds. The wire is designed to undergo reversible phase changes at predetermined temperatures, enabling reliable detection of both local and remote thermal conditions without requiring complex calibration or precision manufacturing
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
Enhances safety by ensuring immediate gas discharge in both local and remote temperature increases, providing enhanced protection against hazardous situations.
Implementation Method 1
a heat sensitive element which extends along a rectilinear trigger axis beyond the multifunction valve, which is operatively connected to the stop, and which comprises at least one heat sensitive section consisting of a wire made of a shape-memory material, which tends to shorten above a critical temperature
Implementation Method 2
a thermal safety device operative between the by-pass duct and the evacuation duct, provided with a bulb which is breakable when exposed to a temperature higher than a threshold safety temperature
Implementation Method 3
an auxiliary device adapted to act mechanically on the bulb to break it, comprising a hammer which is movable between an advanced position, in which it impacts against the bulb
Data Source
AI summary
A multifunction valve for a tank containing high-pressure hydrogen of an automotive fuel cell system is provided. The multifunction valve has a thermal safety device, an auxiliary device adapted to act mechanically on a bulb of the thermal safety device to break the bulb, and a trigger group provided with a heat sensitive element consisting at least in part of a wire made of a shape-memory material.