Radial coverage piston ring groove arrangement

Abstract

A main shaft bearing compartment seal system is described herein. The modified ring groove geometry creates two distinct cavities or steps for a piston ring and a wave spring. This concept provides a separate groove cavity for the spring independent of the fool-proofing and clearance cavity. This modified ring groove geometry increases first face coverage and reduces exposure risk for eccentricity of wave spring to piston ring, to avoid potential disengagement and improve function and performance of the seal assembly and engine. A piston ring may comprise a first face configured to form a first seal between the piston ring and a cylindrical ID bore, a second face configured to form a second seal between the piston ring and a carbon seal assembly, and a third face configured to interface with a surface of a spring, wherein the third face is longer than the surface of the spring.

What is claimed is: 
     
         1 . A piston ring, comprising:
 a first face configured to form a first seal between the piston ring and a cylindrical ID bore;   a second face configured to form a second seal between the piston ring and a carbon seal assembly; and   a third face configured to interface with a surface of a spring, wherein the third face is longer than the surface of the spring.   
     
     
         2 . The piston ring of  claim 1 , wherein the spring is a wave spring. 
     
     
         3 . The piston ring of  claim 1 , wherein the carbon seal assembly comprises a first step and a second step. 
     
     
         4 . The piston ring of  claim 3 , wherein a width of the second step is sized to prevent a portion of the spring from entering a gap formed between the piston ring and the carbon seal assembly. 
     
     
         5 . The piston ring of  claim 3 , wherein dimensions of the first step of the carbon seal assembly provide resistance to improper installation. 
     
     
         6 . The piston ring of  claim 1 , wherein in response to the carbon seal assembly bottom contacting at one circumferential location, the interface between a face of the piston ring and the spring is no less than about 66% coverage of contact between a face of the piston ring and the surface of the spring.