Vane Seals

When a customer requested completely leak-free operation within an aerospace actuator, Trelleborg utilized an innovative new production method to deliver a high-tech vane seal.

-By Jan Sklucki

ROTARY VANE ACTUATORS (RVA) aid in controlling aircraft wing flaps, anti-roll suspension systems on premium cars and machine tools and operate with rotating and oscillating motions. Generally, actuators are designed with one or two vanes but versions are available with three or more.

In a two vane rotary actuator, a rotor replaces the piston, which operates within linear hydraulic cylinders, with two vanes attached. When fluid pressure is applied to two of the four working chambers that turn the actuator, which requires sealing to ensure reliable performance. The vanes allow more power from a smaller envelope, but even small amounts of fluid leakage creates inefficiency and power loss.

Over the years, Trelleborg Sealing Solutions has been looking at more efficient and cost effective vane seal designs, increasing efficiency and performance with each step.

“From milling to stamping, we’ve had successes with creating seals of different shapes and materials to meet our customers’ demanding requirements,” says Steve James, Aerospace Product Engineering Manager at Trelleborg Sealing Solutions.

“Few companies have the combined resources: the material technology, the worldwide engineering resources and the manufacturing capabilities.” says Torben Anderson, Director Aerospace Segment at Trelleborg Sealing Solutions.

However, an aerospace customer involved with commercial aircraft approached Trelleborg Sealing Solutions looking to create a completely leak-free seal to further improve performance and meet environmental requirements.

Traditional vane seals feature an inherent leak path. “The corner actuator seal has been the weak link in the chain, and the industry has been looking for a way to eliminate it for 25 years, with substantial research time dedicated to a solution. After a great deal of development and testing, including designs with springs and trying to tighten the corner’s geometry, we’ve developed a new seal to completely eliminate the corner actuators – and hence removed the leak path entirely,” says Steve.

Using a patented process, a PTFE and bonded elastomer is bent into a geometry to consolidate multiple sealing functions into a single highly engineered part, enabling threedimensional sealing. “It’s the results of decades of experience in sealing, not just in aerospace, but in all industries. Few companies have the combined resources: the material technology, the worldwide engineering resources and the manufacturing capabilities,” ends Torben.

As actuators have developed, manufacturers are looking for better internal performance. The newly released vane seals offer this and more. They can keep up with the requirements of newer, smaller actuators that deliver ten times the power and meet the latest safety guidelines on the market.