Hydrogen Tank Valve Thermal Trigger for Rapid Gas Evacuation
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Solution Overview
Problem
Existing multifunction valves for high-pressure hydrogen tanks in automotive fuel cell systems do not adequately address the need for immediate detection and evacuation of gas under pressure in hazardous conditions, particularly when temperature thresholds are exceeded.
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 critical temperatures, mechanically activates the evacuation of gas through a by-pass and evacuation ducts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal safety device with a breakable bulb is used to detect temperature thresholds, then the safety detection capability is improved, but the response time may be delayed because the bulb requires direct exposure to high temperatures to break
Solution Approach 1:
A heat-sensitive element made of shape-memory material acts as an intermediary between the thermal environment and the breakable bulb. This element detects temperature increases remotely and transmits the thermal signal mechanically through elongation, triggering the bulb to break without requiring direct exposure to extreme temperatures, thus improving response time while maintaining safety detection capability
Solution Approach 2:
The heat-sensitive element is pre-positioned to detect temperature changes before they reach critical levels at the bulb location. By detecting thermal conditions in advance and transmitting the signal through its elongation property, the system prepares for potential failure modes proactively, enabling earlier response to hazardous conditions
2Speed
If a shape-memory material element is used to transmit thermal signals mechanically, then the response speed is improved, but the device complexity increases due to additional components
Solution Approach 1:
The heat-sensitive element made of shape-memory material serves dual functions: it acts as both the temperature sensor and the mechanical actuator. When exposed to temperature changes, it automatically elongates or contracts, directly triggering the release mechanism without requiring external power sources, control electronics, or additional actuating components, thus achieving fast response while minimizing device complexity
Solution Approach 2:
The system exploits the inherent parameter change (dimensional change) of shape-memory materials in response to temperature variations. This physical property transformation is directly coupled to the mechanical release mechanism, converting a material parameter change into a functional action without requiring complex conversion mechanisms, thereby maintaining simplicity while achieving rapid response
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
Ensures immediate and effective gas evacuation in both local and remote temperature increases, enhancing safety by promptly responding to potential hazards.
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
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
An OTV valve (1) for a high-pressure hydrogen tank of an automotive fuel cell system comprises a thermal safety device (15), an auxiliary device (27) adapted to act mechanically on a bulb (21) of the thermal safety device (15) to break it, and a trigger group (43) provided with a heat sensitive element (65) consisting at least in part of a wire made of a shape-memory material.