Two-Stage Propellant Gas Valve for Fine Impulse Control
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Solution Overview
Problem
Existing propellant gas thrusters fail to provide a wide range of thrust levels with fine impulse resolution and adequate propellant management, with poppet valve thrusters offering high thrust but coarse impulse bit performance, pintle valve thrusters having slow response times, and diverter valve thrusters lacking propellant management capabilities.
Innovation Solution
A gas control valve system comprising a pilot stage and a main stage, where the pilot stage receives pressurized gas and control signals to move between closed and open positions, and the main stage responds to differential pressure to switch between low and high flow positions, allowing for precise control of propellant gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If poppet valve thrusters are used, then high thrust levels are provided, but impulse bit performance becomes coarse
Solution Approach 1:
The valve system is divided into two independent stages: a pilot stage with a poppet valve for coarse flow control and a main stage with a pintle valve for fine flow modulation. This segmentation allows each stage to specialize in one aspect of flow control, resolving the contradiction between high thrust capability and fine impulse bit performance.
Solution Approach 2:
The pilot stage valve is nested within the main stage valve assembly. The pilot stage controls the main stage valve opening, creating a hierarchical control structure where the pilot stage provides high thrust capability while the main stage provides fine impulse bit control through its pintle valve mechanism.
2Ease of operation
If pintle valves are used, then modulated output is achieved, but response time becomes slow
Solution Approach 1:
The pilot stage valve opens in advance to establish a controlled gas flow path before the main stage valve begins its modulation cycle. This preliminary action reduces the time required for the main stage to achieve full modulation capability, improving overall response time while maintaining modulated output.
Solution Approach 2:
The system employs dynamic pressure balancing between the pilot stage and main stage, where differential pressure automatically adjusts valve openings during operation. This dynamic response allows the pintle valve to achieve faster modulation response by utilizing pressure differential forces rather than relying solely on mechanical actuation.
3Measurement precision
If diverter valves are used, then thrust levels in the 2 to 20 lbf range are provided with favorable MIB performance, but propellant gas management capability is lost
Solution Approach 1:
The two-stage valve system performs multiple functions: it provides thrust control in the 2-20 lbf range, achieves fine MIB performance through the pintle valve, and enables propellant gas management through the combination of poppet valve cutoff capability and pintle valve modulation. This multi-functionality resolves the contradiction by integrating capabilities that were previously mutually exclusive.
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
Enables thrust control over a wide range from 2 to 20 lbf with fine minimum impulse bit performance, enhancing propellant management and response time, thus addressing the limitations of existing thruster configurations.
Implementation Method 1
The main stage valve is responsive to differential gas pressure between the main stage inlet port and the pilot stage pilot chamber to move between a low flow position and a plurality of high flow positions
Data Source
AI summary
A gas control valve is configured to controllably supply propellant gas to a thruster so that the thruster may produce thrust over a relatively wide range, and so that the thruster exhibits relatively fine minimum impulse bit (MIB) performance. The gas control valve includes a pilot stage having a pilot valve, and a main stage having a main valve. The gas control valve responds to control signals supplied to the pilot stage and is configured such that for commands of relatively short duration, only the pilot valve responds. Conversely, for commands of relatively longer duration, the pilot valve and main valve both respond.