Variable back-up ring and a sealing structure having the same

Abstract

A variable back-up ring includes: a first half shell; a second half shell having a symmetrical shape to the first half shell; and an inner cavity defined by the first half shell and the second half shell. The first half shell and the second half shell are deformable depending on a magnitude of a fluid pressure acting on the first half shell and the second half shell.

What is claimed is: 
     
         1 . A variable back-up ring, comprising:
 a first half shell;   a second half shell having a symmetrical shape to the first half shell; and   an inner cavity defined by the first half shell and the second half shell,   wherein the first half shell and the second half shell are deformable depending on a magnitude of a fluid pressure acting on the first half shell and the second half shell.   
     
     
         2 . The variable back-up ring according to  claim 1 , wherein the first half shell and the second half shell have a reference shape when the fluid pressure is lower than a reference pressure, and
 wherein the reference shape is a shape in which the first half shell and the second half shell contract radially inward.   
     
     
         3 . The variable back-up ring according to  claim 1 , wherein the first half shell and the second half shell have an expanded shape when the fluid pressure is higher than a reference pressure, and
 wherein the expanded shape is a shape in which the first half shell and the second half shell expand radially outward.   
     
     
         4 . The variable back-up ring according to  claim 2 , wherein the shape of the first half shell and the second half shell varies between the reference shape and an expanded shape as the magnitude of the fluid pressure varies. 
     
     
         5 . A sealing structure, comprising:
 a first connector body having a groove;   a second connector body encompassing the first connector body;   an O-ring partially received in the groove of the first connector body; and   a variable back-up ring partially received in the groove of the first connector body, holding the O-ring, the variable back-up ring being deformable in a radial direction depending on a magnitude of a fluid pressure applied between the first connector body and the second connector body.   
     
     
         6 . The sealing structure according to  claim 5 , wherein the variable back-up ring includes an inner circumferential surface contacting the groove of the first connector body and an outer circumferential surface facing an inner circumference of the second connector body, and
 wherein a position of the outer circumferential surface of the variable back-up ring is variable in the radial direction of the variable back-up ring depending on the magnitude of the fluid pressure.   
     
     
         7 . The sealing structure according to  claim 5 , wherein the shape of the variable back-up ring is variable so that the outer circumferential surface of the variable back-up ring is brought into contact with the inner circumference of the second connector body when the magnitude of the fluid pressure is higher than a reference pressure. 
     
     
         8 . The sealing structure according to  claim 5 , wherein the groove of the first connector body includes a base surface recessed radially inward from an outer circumference of the first connector body, a first side relatively close to a source of the fluid pressure, and a second side opposing the first side,
 wherein the O-ring is relatively close to the first side, and   wherein the variable back-up ring is relatively close to the second side.