SMA Wire Trigger for Fuel Cell Thermal Gas Evacuation
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Solution Overview
Problem
High-pressure hydrogen fuel cell systems require a remote trigger device for thermal safety devices that can quickly and reliably detect dangerous conditions and initiate gas evacuation with enhanced operational reliability.
Innovation Solution
A trigger device for a multifunction valve in a fuel cell automotive system, utilizing a heat-sensitive element made of shape-memory material (SMA wire) and an auxiliary device with a hammer mechanism to break a temperature-sensitive bulb, allowing for immediate gas evacuation when the temperature exceeds a threshold, without the need for tensioned SMA wire or additional elastic compensating elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tensioned SMA wire with delay spring device is used to compensate for unwanted elongations, then the trigger device can maintain operational reliability, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent removes the delay spring device from the trigger mechanism, extracting the problematic component that caused complexity. The simplified design uses only the SMA wire and bulb assembly without additional elastic compensating elements, thereby reducing device complexity while maintaining reliability through the inherent properties of the shape memory material.
Solution Approach 2:
The SMA wire is designed to self-compensate for thermal expansion and elongation effects through its shape memory properties. The wire automatically adjusts to temperature changes without requiring external compensation mechanisms, making the system self-regulating and eliminating the need for complex delay spring devices.
2Reliability
If multiple elastic compensating elements are added to the trigger device, then component stress and fatigue are reduced, but the manufacturing complexity and assembly difficulty increase
Solution Approach 1:
The patent eliminates additional elastic compensating elements from the design, removing components that would complicate manufacturing and assembly. The design relies on the inherent properties of the SMA wire and simple mechanical linkages, significantly reducing the number of parts that need to be manufactured and assembled.
Solution Approach 2:
Instead of adding complex compensation mechanisms to protect against stress and fatigue, the patent inverts the approach by designing a system where the SMA wire operates within its optimal stress range through proper pre-tensioning and geometric design. The bulb assembly naturally provides the necessary mechanical advantage to reduce stress concentrations without additional elastic elements.
3Manufacturing precision
If the SMA wire is held taught by a delay spring device, then unwanted elongations are compensated, but vibrations and fatigue stresses increase
Solution Approach 1:
The patent removes the delay spring device that was causing vibrations and fatigue stresses. By eliminating this elastic component, the system experiences reduced mechanical oscillations and lower fatigue loading on the SMA wire, while trigger activation precision is maintained through the direct mechanical coupling of the simplified components.
Solution Approach 2:
The SMA wire's shape memory properties enable it to self-regulate its length and tension in response to temperature changes without generating harmful vibrations. The material's inherent damping characteristics and controlled phase transition reduce fatigue stresses while maintaining precise trigger activation through its natural response to thermal stimuli.
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
The solution ensures high operational reliability and simplicity in manufacturing, reducing stress on components and eliminating the need for tensioned SMA wire, which minimizes vibrations and fatigue, thereby enhancing the safety and efficiency of gas evacuation.
Implementation Method 1
a heat-sensitive element (65) made of a shape-memory material (SMA wire)
Implementation Method 2
a temperature-sensitive bulb (21) which, when intact, is configured and arranged in such a way to prevent the translation of the shutter (17)
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A trigger device (43) for a thermal safety device (15) of a fuel cell automotive system comprises a stop (46), a heat sensitive element (65) consisting of a wire made of a shape-memory material, and a trigger abutment (75). In an intermediate configuration of the trigger device, the distal end (69) of the heat sensitive element (65) is freely slidable by means of the shortening of the heat sensitive element (65); in an activation configuration of the trigger device, in which the temperature (T) perceived by the heat sensitive section of the heat sensitive element (65) is above or equal to the activation temperature (T1), the distal end (69) abuts against the trigger abutment (75), so that the proximal end (67) is adapted to move the stop (46) to bring the thermal safety device (15) into the remote emergency configuration.