Developement of a Closed-Loop Electromechanical Pressure Regulator for an Orbital Spacecraft

The propulsion system of a spacecraft is one of the most critical subsystems. For pressure-fed systems, the pressurization of propellant tanks is a key part. Accurate regulation of the propellant tank pressures ensures reliable thruster operations and precise spacecraft maneuvering. In this paper we present the development of an electromechanically operated pressure regulator (PR) for an orbital spacecraft. The PR presented in this paper is a discrete "bang-bang" type regulator designed for nitrogen pressurization systems. It consists of a main housing in which two different electromagnetic solenoid valves (EV) are integrated. The EVs feature different flow sections. One EV operates under high to medium US pressure conditions, while the other functions in medium to low pressure conditions, with a total operational range from 300 bar to below 30 bar. The intended total operational range is from 300 bar to beneath 30 bar upstream pressure. A key feature of the PR is its high responsiveness to keep the propellant tank pressure inside a narrow range. This includes the valves and the command chain. Such a narrow range must be guaranteed, even if the pressure gradients in the tank change rapidly. To comply to this requirement, for the control mechanism a closed loop regulation cycle was selected, which controls EV actuations based on the sensed pressure information. This paper describes the full design and verification process from pre-design and analysis towards testing and improvements of such regulator product.