For the aircraft engines which require high-density mounting, the seal must be very compact and light in weight, too. EKK has wide experience in the application of seals for aircraft services and has introduced the compact seals of the 700 series (the EKU750 and the EKU770) and the 800 series (the EBU800) in the market. The sizes of these seals are now regarded as the industry standards. Especially, the 800 series are the most precise and compact seals, utilizing a welded metal bellows as the secondary seal, and provides the world’s best rotating performance in high speed, high temperature and extremely low temperature conditions. The 800 series seal is used in the liquid oxygen service for the secondary propulsion engine and in the liquid hydrogen turbo-pump for the primary propulsion engine of the domestic rocket “H-II A”.
This segmented seal was originally developed as the main shaft bearing seal for aircraft gas turbines. The main feature is a unique segmented construction which requires accurate machining and finishing techniques. Since the seal consumes less buffer gas and saves energy due to the superior performance as a gas seal, it has been regarded highly among the plants handling toxics or inflammable gases. The seal demonstrates superior durability due to the low torque rotation design. Today, the seal has a wide range of applications from aircraft and rockets such as the “H-1” and “H-2” domestic produced rockets, to general industrial applications such as blowers, compressors and fans, establishing a reputation for high performance and reliability.
The ACTISEAL-C and ACTISEAL-E are elastic gaskets which have the equivalent composition and temperature/pressure characteristics to the metal O-ring, yet achieve high spring characteristics and low load characteristic due to the special structure design and enhance the function to keep sealing flexibly and tightly in case of a flange distortion. These seals demonstrate stable sealing performance under extremely low temperature, high temperature and high pressure conditions.
The brush seal consists of ultra thin wires and two plates. The seal follows the change of clearances between the stator and the rotor and misalignment flexibly to achieve excellent sealing capability, so is supposed to improve engine output and fuel efficiency significantly. Traditionally, the brush seal was used in aircraft gas turbines and contributed to reduce leakage of secondary air. Today, it is improved for large-size industrial gas turbines and installed to late-model gas turbines instead of a labyrinth seal.
Special Application Seal
NASDA (National Space Agency of Japan) is developing the H-IIA rocket in response to varied future demands in space transport including satellite launch and the ferrying of logistics in conjunction with International Space Station construction. Building on successes achieved with the H-II rocket, Japan’s primary launch vehicle of the 1990s, the H-IIA rocket program is aimed at realizing a highly reliable vehicle with minimal launch cost. In this important national project, EEA has played important roll of developing rocket engine seals. These seals are used in liquid oxygen service or liquid hydrogen turbo-pumps for the primary propulsion rocket engine.s
Floating-ring seals provide dependable shaft sealing where speeds, temperatures, and lack of lubrication prohibit the use of conventional face-type seals. This type of seal is excellent for sealing hot gases from bearings or other mechanisms. In addition to being able to operate in conditions beyond the capability of face-type seals, these simple seals offer other significant advantages. It minimized leakage due to controlled clearance. Unlimited axial shaft movement. Long life because of limited rubbing and wear. Very low heat generation. Reduced coking. Simpler to install than face-type or segmented seals. Compact package works within space limitations of new compact turbine designs.
Mainshaft Face Type Seal
Face type seals used on large engine mainshafts are similar in construction to conventional our compact mechanical seals, but have additional characteristics to handle the surface speeds, temperatures and pressure typically required of such applications. The carbon seal ring stator is housed into a metal carrier and is spring loaded against the mating ring by a series of coil springs. Due to the temperature requirements, elastomers are not used. Instead, the secondary seal is one or two piston rings comprised of metal carbon graphite, or Teflon jacketed spring seal. At high speeds and pressures, some seals are configured to introduce oil lubrication directly at the interface, and is achieved by a flow of oil introduced through lubrication at the interface. A mating ring is usually located next to bearing. In the case of the seal for high-speed application, since there is also much higher heat generation from a mating ring, this heat generated by friction must be efficiently removed. Then, a good heat conductivity and also a good wear resistance material is used. In order to acquire a good seal performance, the roughness of the surface of a mating ring, and a surface deflection must be controlled minimum. For this reason, a design must be surveyed from the point of minimizing deflection in various conditions.