Fuel cap

Abstract

A fuel cap comprising a seal ring 1 mounted on a cap trunk portion 223 to realize liquid tightness and gas tightness, wherein the seal ring 1 includes a ring body 11 and an elastic support portion; the ring body 11 has a sizing relation between an external diameter Dc of the cap trunk portion 223 and an internal diameter Din of the ring body 11 which is Dc<Din, and has a C-shaped section formed by a wedged circumferential groove opening outward in radial direction of the ring; and the elastic support portion is a plurality of the elastic members 12,13,14,15,16 or one of the elastic flanges 17,18 , or combination thereof, and disposed on the inner circumference side of the ring body 11 and protrudes with an amount of a radially inward protrusion d set at (Din−Dc)/2 or greater.

1 . A fuel cap comprising a seal ring mounted on a cap trunk portion to realize liquid tightness and gas tightness, wherein: the seal ring includes a ring body and an elastic support portion; 
 the ring body has a sizing relation between an external diameter Dc of the cap trunk portion and an internal diameter Din of the ring body which is Dc<Din, and has a C-shaped section formed by a wedged circumferential groove opening outward in radial direction of the ring; and    the elastic support portion is disposed on the inner circumference side of the ring body and protrudes with an amount of a radially inward protrusion d set at (Din−Dc)/2 or greater.    
   
   
       2 . A fuel cap according to  claim 1 , wherein the elastic support portion includes a plurality of elastic ridges circumferentially arranged, and wherein the elastic ridges are vertical members extending in circumferentially perpendicular direction.  
   
   
       3 . A fuel cap according to  claim 1 , wherein the elastic support portion includes a plurality of elastic ridges circumferentially arranged, and wherein the elastic ridges are horizontal members extending in circumferential direction.  
   
   
       4 . A fuel cap according to  claim 1 , wherein the elastic support portion includes a plurality of elastic ridges circumferentially arranged, and wherein the elastic ridges are cross members extending in mutually-perpendicular direction.  
   
   
       5 . A fuel cap according to  claim 1 , wherein the elastic support portion includes a plurality of elastic ridges circumferentially arranged, and wherein the elastic ridges are cantilever support members bridged in circumferential direction.  
   
   
       6 . A fuel cap according to  claim 1 , wherein the elastic support portion includes a plurality of elastic ridges circumferentially arranged, and wherein the elastic ridges are center-impeller support members bridged in circumferential direction.  
   
   
       7 . A fuel cap according to  claim 1 , wherein the elastic support portion is an elastic flange extending in circumferential direction of the ring body.  
   
   
       8 . A fuel cap according to  claim 1 , wherein the elastic support portion includes an elastic flange extending in circumferential direction of the ring body, and an auxiliary ring disposed at the inner circumference edge of the elastic flange.