Feature: Avionics


Solenoid valves regulate pressures in


critical aerospace systems By The Lee Company engineers


I


n the aerospace and aviation industries, pneumatic systems are used to control the flow of fuel and other essential fluids for propulsion, thrust, lubrication, isolation, purge and other fluid-


control applications. These pneumatic systems are usually supplied by a tank of compressed gas, where one of the main challenges is to eliminate the possibility of leakage (or excess flow) from the tank, shortening system life or requiring a larger tank. In these situations, a solenoid valve


that offers the key benefits of zero leakage along with a wide operating pressure range can be an effective barrier between the tank and the system. However, engineers will also have to consider other factors with a direct impact on the performance of the solenoid valve. For example, various combinations of operating temperatures, material compatibility, power limitations and expected life cycle all add to design complexity.


34 October 2022 www.electronicsworld.co.uk


An effective solution Precision micro-hydraulic specialists Te Lee Company has been at the forefront of fluid control technology since 1948, and is known for its smallest solenoid valves on the market. More importantly, Lee’s solenoid valves have proven themselves over decades of use in demanding aerospace applications, along with other applications involving harsh conditions, ranging from the high temperatures and pressures of subsea oil wells to the cold and vacuum of outer space. A good example of this is the ongoing


development of the Zero-Leak Pneumatic Solenoid Valve, which has proven to be an ideal barrier for aerospace pneumatic systems. It features a polyimide shaſt tip that ensures a bubble-tight seal on nitrogen, in a package weighing only 2.24 ounces, with a direct-acting design that operates without pressure assistance, and which handles flows up to 30SLPM of air at 200psi differential. Ultra-compact and energy efficient, the


70-ohm solenoid coil requires less than 4W to open the valve and, for more demanding applications, custom configurations are


available with 6000psi operating capability, or qualified for over one million cycles.


Benefits and applications Te valve configuration was initially developed to meet the difficult requirements associated with solenoid barrier valves used in spacecraſt, where it typically controls flow from a tank upstream of a satellite’s propulsion system. Tey are also used in launch vehicles as piloting valves for isolating the pneumatics, whether for fuel, oxidiser or helium purge systems, as well as being used to control thrust vector actuators. Aircraſt systems also require barrier valves, used on tanks of compressed gas, landing gear and braking systems, all of which have pneumatic back- up systems. Lee’s zero-leak pneumatic solenoid


valves are just one example of its range of powerful industry-specific products for a wide range of applications. Tis illustrates a passion for innovation which enables its customers to solve their toughest fluid control problems.


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