Remote Pressure Vessel Triggering via Thermal Expansion Lock Release
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Solution Overview
Problem
Existing pressure relief valves in compressed gas reservoirs, especially in vehicles, lack reliable remote triggering mechanisms that are not influenced by aging or settling processes and cannot effectively detect high temperatures from distant locations without being directly exposed to mechanical loads.
Innovation Solution
A remote triggering device with a piezoelectric element and a piston, where the piston is held in a temperature-sensitive locking mechanism that uses thermal expansion to release and generate a voltage signal to trigger the pressure relief valve, featuring a press fit locking mechanism that transitions from a clamping to a clearance fit at a defined temperature, ensuring reliable operation and resistance to external mechanical loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a pressure relief valve is directly exposed to high temperature locations for immediate detection, then the response speed is improved, but the device is subjected to direct mechanical loads and thermal stress that reduce reliability
Solution Approach 1:
The system is divided into two separate components: a remote triggering device located away from the high-temperature compressed gas reservoir that detects temperature remotely, and a pressure relief valve located at the reservoir that responds to triggering signals. This segmentation allows the detection function to be performed in a safer location while maintaining rapid response capability through the triggering mechanism.
Solution Approach 2:
A triggering signal acts as an intermediary between the remote temperature detection and the pressure relief valve activation. The triggering device converts thermal expansion into an electrical signal that remotely activates the pressure relief valve, allowing the valve to respond quickly without being directly exposed to high temperatures or mechanical loads.
2Device complexity
If a simple mechanical fuse design is used for the pressure relief valve, then the device complexity is reduced, but the reliability under varying temperature conditions deteriorates due to aging and settling processes
Solution Approach 1:
The locking mechanism utilizes changes in dimensional parameters of the housing and piston due to thermal expansion. As temperature increases, the dimensions of these components change, automatically altering the locking force. This parameter change provides a temperature-compensated locking mechanism that maintains reliability without complex control systems or aging-sensitive components.
Solution Approach 2:
The housing and piston are designed with different coefficients of thermal expansion so that under increasing temperature, the housing expands more than the piston, causing the press fit to transition from a clamping fit to a clearance fit. This thermal expansion mechanism automatically releases the piston to strike the piezoelectric element at a predetermined temperature, providing reliable operation independent of aging or settling processes.
3Reliability
If the piston is held in the starting position with a strong locking mechanism, then the false triggering is prevented, but the release speed at threshold temperature is reduced
Solution Approach 1:
The locking mechanism is designed so that the thermal expansion of the housing relative to the piston automatically overcomes the locking force at a predetermined temperature. The differential expansion provides a rapid release mechanism that maintains strong locking under normal conditions but enables quick release when the temperature threshold is reached, balancing false triggering prevention with rapid response capability.
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 provides a simple, high-reliability remote triggering mechanism that effectively opens the pressure relief valve at a predetermined temperature, maintaining functional integrity over decades and resisting mechanical loads, enhancing operational safety by allowing remote detection of high temperatures without direct contact.
Implementation Method 1
a piezoelectric element (26)... the piston (22) is applied by the prestressing device (24) against the piezoelectric element (26) and generates there a voltage signal
Implementation Method 2
the holding force generated by it becomes smaller when a limit temperature is exceeded than the force generated by the prestressing device... based on the basic idea of using the thermal expansion of the housing and of the piston as a triggering mechanism
Data Source
AI summary
A remote triggering device comprises a housing, a piezoelectric element, a piston accommodated in the housing, and a prestressing device. The piston is adjustable between a starting position in which the prestressing device is held in a pretensioned state and an actuating position in which the piston is applied by the prestressing device against the piezoelectric element. The piston is held in the starting position by a temperature-sensitive locking mechanism. An assembly comprises a compressed gas reservoir, an electrically-actuated pressure relief valve that is attached to the compressed gas reservoir, and the remote triggering device.