Fluid Ejection Device Thimble Seal Segmentation
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Solution Overview
Problem
Fluid ejection devices used in aircraft, such as fire extinguishers and emergency hydraulic generators, face challenges with sensitivity to microleaks, complex maintenance requirements, and inefficiencies due to temperature-induced volume variations of the extinguishing agent, leading to overpressure issues and reduced ejection efficiency.
Innovation Solution
A compact fluid ejection device with a cylindrical reservoir divided into two chambers by a piston, featuring a thimble for sealing and a pyrotechnic gas generator for pressurization, which ensures perfect and durable sealing between chambers, preventing fluid loss and heat transfer, and allowing for sequential triggering of multiple reservoirs without excessive pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the reservoir is designed to contain pressurized gas and extinguishing agent, then the device can provide sufficient pressurization for ejection, but the wall thickness must be increased to prevent overpressure, which increases the overall mass
Solution Approach 1:
The reservoir is divided into two separate chambers: a first chamber for pressurized gas and a second chamber for extinguishing agent, separated by a piston. This segmentation allows each chamber to be optimized independently - the gas chamber can be pressurized without requiring the entire reservoir to have increased wall thickness, thus reducing overall mass while maintaining pressurization capability.
Solution Approach 2:
A piston is introduced as an intermediary element between the gas chamber and the extinguishing agent chamber. The piston transmits pressurization force from the gas to the extinguishing agent while maintaining physical separation. This allows the reservoir to achieve high pressurization without requiring the entire structure to be reinforced, reducing weight.
2Reliability
If the reservoir walls are made thicker to ensure safety and prevent overpressure, then the device becomes more secure, but the overall mass increases which penalizes aircraft performances
Solution Approach 1:
By segmenting the reservoir into separate chambers for gas and extinguishing agent, the design allows the gas chamber to handle pressurization safely without requiring the entire reservoir structure to be heavily reinforced. The piston provides a mechanical interface that safely transmits pressure while maintaining separation.
Solution Approach 2:
The piston acts as an intermediary that safely mediates between the pressurized gas and the extinguishing agent. It provides a controlled interface for pressure transmission while preventing direct contact between the two chambers, thereby ensuring safety without requiring excessive wall thickness throughout the entire reservoir.
3Productivity
If the extinguishing agent volume is increased to maintain concentration at target area, then the ejection efficiency improves, but temperature-induced volume variations cause overpressure in the pressurization chamber
Solution Approach 1:
The reservoir is segmented into two independently controllable chambers. The first chamber contains only pressurized gas while the second chamber contains the extinguishing agent. This segmentation isolates the volume variations of the extinguishing agent from the pressurization chamber, preventing temperature-induced overpressure while allowing sufficient extinguishing agent volume for efficient ejection.
Solution Approach 2:
The piston serves as an intermediary that mechanically couples the two chambers while allowing independent volume control. It transmits pressurization force from the gas chamber to the extinguishing agent chamber without transmitting volume expansion forces, thereby preventing overpressure while maintaining ejection efficiency.
4Productivity
If a separation means such as membrane or piston is used to limit heat transfers, then the extinguishing agent efficiency is improved, but the sealing becomes sensitive to microleaks requiring severe monitoring
Solution Approach 1:
The piston is positioned as an intermediary element between the gas chamber and extinguishing agent chamber. It provides a robust mechanical seal that effectively limits heat transfer while its design and positioning reduce sensitivity to microleaks compared to thin membranes, improving reliability while maintaining thermal insulation for ejection efficiency.
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 device maintains reliability and efficiency across a wide temperature range, reduces bulk and weight, and enables maximum concentration of the extinguishing agent at the target area, while minimizing maintenance and safety risks.
Implementation Method 1
a pyrotechnic gas generator (7) positioned in said first enclosure (A)
Implementation Method 2
said thimble (50) consisting of a diametrically expandable flexible material
Implementation Method 3
The purpose of this separation means is to limit heat transfers between the generated gas and the extinguishing agent
Data Source
AI summary
A compact device for ejecting a fluid including two chambers separated by a separating element of piston type. One of the chambers contains the fluid intended to be ejected, the other chamber is a pressurization chamber, the pressurization of which can cause translational movement of the separating element and ejection of the fluid. The pressurization chamber includes a thimble capable of sealably separating the inside of the pressurization chamber from the side walls of the reservoir. Thus, a seal between two chambers is perfect and durable without degrading slidability of the piston.