Low friction O-ring for use in a carbon face seal

Abstract

A stator seal assembly is provided that includes a seal case, an O-ring and a stator ring. The seal case has an inner peripheral wall, an outer peripheral wall, and an annular cavity formed therebetween. The O-ring is coupled to the seal case inner peripheral wall and disposed in the annular cavity, and is constructed of a material having stress versus strain ratio of less than about 5 ksi and a Shore M value of between about 30 and 50. The stator ring is disposed within the seal case annular cavity.

Description

TECHNICAL FIELD [0001] The present invention relates to gas turbine engines and, more particularly, to a seal assembly for use in gas turbine engines, gas turbine engine starters, and auxiliary power units. BACKGROUND [0002] Air turbine starters (ATS) may be used to initiate rotation of many relatively large turbine engines, including turbofan jet engines. Typically, the ATS is disposed within a housing and includes a turbine section and an output section. The turbine section includes a turbine wheel coupled to an output shaft. When high pressure fluid, such as compressed air, enters the ATS, it contacts the turbine wheel and causes it to rotate at a relatively high rate of speed. As the turbine wheel rotates, the output shaft also rotates, which in turn, causes the jet engine to rotate. The ATS output shaft may be rotationally mounted within the housing using one or more bearing assemblies. Preferably, a lubricant, such as oil, is contained within the housing to lubricate the outpu...

AI Technical Summary

Benefits of technology

[0008] The present invention provides a stator seal assembly including a seal case, an O-ring and a stator ring. The seal case has an inner peripheral wall, an outer peripheral wall, and an annular cavity formed therebetween. The O-ring is coupled to the seal cas

Problems solved by technology

However, it has been found that during operation, some of these O-rings may become deformed or compression set due to prolonged exposure to heat.

As a result, if rotor axial movement occurs, the O-ring may supply an excessive amount of friction against the return motion of the seal ring.

High axial O-ring friction may prevent the seal ring from properly sealing against the rotor.

Consequently, lubricant may leak out of the ATS gearbox at the turbine section and / or output section and assembly maintenance and / or repair may need to be more frequently performed.

Identifying suitable elastomers that may be less likely to demonstrate excessive axial friction when compression set within the seal assembly has been somewhat difficult.

Because there may be numerous materials that may have similar durometer values, identification of appropriate O-ring materials is currently performed by trial and error.

This method of identification may be extremely time-consuming and does not take into consideration whether the elastomer properties may change over time and after exposure to friction.

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