Propellant gas supply for an ionic propulsion unit

Patent metadata

Field	Value
Publication number	US-2015300329-A1
Application number	US-201314439958-A
Country	US
Kind code	A1
Filing date	Oct 21, 2013
Priority date	Oct 30, 2012
Publication date	Oct 22, 2015
Grant date	—

Abstract

A field of feeding propellant gas to ion thrusters, and in particular a method of feeding an ion thruster with propellant gas coming from a pressurized tank via a feed circuit including an on/off valve and, in succession downstream from the on/off valve, a high pressure restrictor, a buffer tank, and at least one low pressure restrictor. The method includes the steps of calculating a pressure setpoint for the buffer tank as a function of a flow rate setpoint, calculating the difference between the pressure setpoint for the buffer tank and a pressure measured in the buffer tank, calculating a setpoint for the opening time of the on/off valve as a function of the difference and of a pressure inside the pressurized tank, and opening the on/off valve in compliance with the opening time setpoint.

First claim

1 . A method of feeding an ion thruster with propellant gas coming from a pressurized tank via a feed circuit comprising an on/off valve and, in succession downstream from said on/off valve, a high pressure restrictor, a buffer tank, and at least one low pressure restrictor, the method comprising the steps of:
calculating a pressure setpoint for the buffer tank as a function of a flow rate setpoint; calculating the difference between the pressure setpoint for the buffer tank and a pressure measured in the buffer tank; calculating a setpoint for the opening time of the on/off valve as a function of said difference and of a pressure inside said pressurized tank; and opening the on/off valve in compliance with said opening time setpoint.

2 . The feed method according to claim 1 , wherein said opening time setpoint is calculated on the basis of an inverse fluid flow model for said feed circuit.

3 . The feed method according to claim 1 , wherein the pressure setpoint for the buffer tank is calculated on the basis of an inverse fluid flow model of the at least one low pressure restrictor downstream from the buffer tank.

4 . The feed method according to claim 1 , wherein the opening of the on/off valve in compliance with the opening time setpoint is triggered only if the pressure setpoint for the buffer tank is substantially greater than the pressure measured in the buffer tank.

5 . The feed method according to claim 1 , wherein the opening of the on/off valve in compliance with the opening time setpoint is triggered only if the pressure measured in the buffer tank is decreasing or zero.

6 . The feed method according to claim 1 , wherein the opening of the on/off valve in compliance with the opening time setpoint is triggered only if the opening time setpoint is greater than a predetermined minimum threshold.

7 . The feed method according to claim 1 , wherein said propellant gas feed circuit includes a bifurcation downstream from the low pressure restrictor, having a first branch for feeding an anode section of the ion thruster and a second branch for feeding a cathode section of the ion thruster, each of said first and second branches having a respective additional restrictor.

8 . The feed method according to claim 1 , wherein the pressure inside said pressurized tank is measured indirectly on the basis of an initial pressure and of an overall flow of propellant gas that has passed through the feed circuit.

9 . The feed method according to claim 1 , wherein said propellant gas feed circuit also includes a safety valve upstream from the on/off valve.

10 . A device for feeding an ion thruster with propellant gas, the device comprising:
a pressurized tank for the propellant gas; and a feed circuit connected to the pressurized tank and comprising at least an on/off valve, a high pressure restrictor, a buffer tank, and a low pressure restrictor connected in succession downstream from the pressurized tank; and a control unit for controlling the on/off valve and configured to: calculate a pressure setpoint for the buffer tank as a function of a flow rate setpoint; calculate the difference between the pressure setpoint for the buffer tank and a pressure measured in the buffer tank; calculate a setpoint for the opening time of the on/off valve as a function of said difference and of a pressure inside said pressurized tank; and command opening of the on/off valve in compliance with said opening time setpoint.

Assignees

• Snecma

Inventors

• Klein Manuel
• Le Gonidec Serge

Classifications

• F03H1/0012 Primary

  Means for supplying the propellant · CPC title

• G05D16/2013

  using throttling means as controlling means · CPC title

• B64G1/402

  Propellant tanks; Feeding propellants · CPC title