Pyrotechnic Gas Generator for Constant Liquid Delivery
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Solution Overview
Problem
Conventional fire extinguisher devices with pyrotechnic gas generators face challenges in maintaining consistent pressure and delivery rate due to the decreasing combustion surface area of pyrotechnic charges, leading to inefficient liquid delivery and the need for oversized structures to compensate for pressure drops.
Innovation Solution
The method involves using pyrotechnic charges with inhibited combustion surfaces to generate a quasi-constant combustion gas flow, ensuring almost constant pressurization and delivery rate of the liquid, achieved through specific charge geometries and combustion inhibition techniques, such as varnishing parts of the charge to control the combustion surface and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If pyrotechnic charges with decreasing combustion surface area are used, then the device structure can be simplified, but the liquid delivery rate becomes inconsistent and decreases over time
Solution Approach 1:
The pyrotechnic charge is designed with non-uniform combustion characteristics by creating zones with different combustion speeds. The charge contains a fast-burning zone and a slow-burning zone, where the fast-burning zone compensates for the decreasing surface area by maintaining higher combustion intensity, thereby sustaining consistent gas generation and liquid delivery rate throughout the discharge process
Solution Approach 2:
The invention changes the combustion parameters of the pyrotechnic charge by controlling the distribution of oxidizer and fuel, as well as the porosity and density of different zones within the charge. This allows the combustion speed to be modulated spatially, ensuring that the gas generation rate remains constant even as the combustion surface area decreases
2Productivity
If higher initial pressure is provided to compensate for pressure drop, then the delivery rate consistency is improved, but the device weight and size increase
Solution Approach 1:
The pyrotechnic charge is designed to self-regulate its combustion process through internal zone differentiation. The fast-burning and slow-burning zones work in conjunction to automatically maintain constant pressure without requiring external control mechanisms or oversized pressure vessels, thereby avoiding the weight penalty associated with over-engineered containment structures
3Duration of action of moving object
If pyrotechnic charges with large dimensions are used to extend operating time, then the duration of action is improved, but the combustion surface area decreases rapidly leading to pressure drop
Solution Approach 1:
The pyrotechnic charge is segmented into functional zones with different combustion characteristics. The charge is divided into a fast-burning zone that provides initial high pressure and a slow-burning zone that sustains pressure over time. This segmentation allows the system to maintain adequate operating time while preventing rapid pressure decay that would occur with uniform large-dimension charges
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
This approach maintains a consistent liquid delivery rate and pressure, reducing the need for oversized structures and ensuring efficient and effective extinguishing agent dispersion, while also simplifying the device design by avoiding complex nozzle systems.
Implementation Method 1
the combustion of at least one pyrotechnic charge to generate combustion gases, the pressurization of said liquid under the action of said combustion gases
Data Source
Figure 1~1C
Figure 2~3.1
AI summary
The present invention mainly concerns a method for delivering a liquid (L) contained in a tank (1), said tank (1) having at least one port (2) for delivering said liquid (L) sealed by a seal (3) that can be retracted when a threshold pressure is applied to said liquid (L), comprising: the combustion of at least one pyrotechnic charge (7) in order to generate combustion gases, the pressurisation of said liquid (L) under the action of said combustion gases, and the retraction of said retractable seal (3) from said at least one delivery port (2) and the delivery of said pressurised liquid (L), characterised in that the flow of generated combustion gases during the delivery of said liquid (L) provides almost constant pressurisation of said liquid (L) and therefore the delivery of said liquid (L) at an almost constant flow rate; the pressure of said liquid (L) during the delivery of said liquid varying by a maximum of only +/- 30 %, advantageously by a maximum of only +/- 20 %, and very advantageously by a maximum of only +/- 10 %, relative to the initial of same at the time when said seal or seals (3) is/are retracted; and in that it is implemented in a device (100; 101; 102) comprising said tank (1) and at least one pyrotechnic gas generator (15; 16; 17) containing said at least one pyrotechnic charge (7; 7'; 70; 700; 700'); said at least one pyrotechnic gas generator (15; 16; 17) being connected to said tank (1) and a movable member (4) for separating the generated combustion gases and said liquid (L) being provided inside said device (100; 101; 102).