Proportional Xenon Flow Control for Stable Spacecraft Propulsion
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Solution Overview
Problem
Existing gas flow regulation devices for spacecraft propulsion systems, such as those using xenon gas, suffer from pressure variations and inability to regulate flow in the event of valve failure, due to 'bang bang' regulation methods and complex multi-valve configurations.
Innovation Solution
A device with a proportional control valve system, including a pressure measuring member upstream of the first valve and an electronic data acquisition unit to control both valves, allowing for precise regulation of gas flow and pressure, with a thermal proportional control valve and redundancy in case of valve failure, ensuring stable and precise flow between 0 and 20 mg/s.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If 'bang bang' regulation method with downstream pressure switch is used, then pressure control is achieved, but pressure variations of at least 5% occur around set pressure
Solution Approach 1:
The patent implements a feedback control system where a pressure sensor continuously monitors the actual pressure downstream of the first valve, and this measured pressure is fed back to the control unit. The control unit adjusts the first valve's opening degree based on the difference between set pressure and actual pressure, replacing the simple on/off feedback of the pressure switch with continuous proportional feedback, thereby eliminating pressure variations and achieving stable pressure control.
Solution Approach 2:
The patent transitions from static on/off valve control to dynamic proportional control. The first valve is controlled in proportion to the pressure measurement, allowing the valve opening to vary continuously rather than remaining fixed in either fully open or fully closed positions. This dynamic adjustment mechanism enables the system to maintain stable pressure despite fluctuations in gas flow or downstream conditions.
2Reliability
If two 'on/off' valves are arranged in series with control valves in each branch, then flow regulation capability is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent extracts the flow regulation function from the branch-level control valves and consolidates it at the main withdrawal line. By placing a single proportional control valve (the first valve) in the main gas supply line and using electronic control with pressure feedback, the system achieves reliable flow regulation without requiring multiple mechanical control valves in each branch, thereby reducing overall system complexity while maintaining regulation capability.
Solution Approach 2:
The patent introduces an electronic control unit as an intermediary between the pressure sensor and the first valve. This electronic mediator processes the pressure signal and controls the valve opening proportionally, replacing the need for complex mechanical linkage between multiple valves and pressure switches. The electronic intermediary enables precise control with simpler mechanical components.
3Measurement precision
If downstream pressure switch controls the second valve, then pressure regulation is achieved, but regulation capability is lost in case of valve failure
Solution Approach 1:
The patent positions the first proportional control valve upstream of the second valve and implements pressure measurement and control at this upstream location. This preliminary control action allows the system to regulate pressure before the gas reaches the second valve, ensuring that even if the second valve fails, the first valve can maintain proper pressure regulation through its proportional control mechanism and feedback system.
Solution Approach 2:
The patent creates a buffered control system by implementing upstream pressure control with proportional adjustment. The first valve's proportional opening capability and the electronic feedback system provide a cushion against failure conditions, allowing the system to maintain regulation capability even when downstream components fail, unlike the brittle on/off control system that loses regulation capability upon valve failure.
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 achieves precise gas flow regulation with minimal pressure fluctuations (around 1%) and increased reliability by enabling proportional control and redundancy, improving the stability and endurance of the gas flow system.
Implementation Method 1
the proportional control valve activated by thermal effect is normally closed when it is not heated above a determined threshold, for example between 50 and 180°C and preferably between 80 and 120°C
Data Source
Figure 1~3
AI summary
Device and method for regulating a flow rate of gas intended to supply a propulsion apparatus for a spacecraft comprising xenon tank (2), a circuit comprising a withdrawing pipe (3) having an upstream end connected to the tank (2) and a downstream end (4, 5) connected to a propulsion member (6), the withdrawing pipe (3) comprising an isolation first valve (7), a regulating second valve (8) and a member (9) for measuring the pressure downstream of the regulating second valve (8). The regulating second valve (8) regulates the flow rate and/or the determined pressure according to the pressure measured. The regulating second valve (8) is a proportional valve of electrically operated variable throughput PCV type.