Piping unit for transporting fuel

Abstract

Piping unit for transporting a fuel is constructed by connecting a resin tube and a connector for connecting the resin tube to a mating pipe. The connector has a connector body including a retainer holding portion and a retainer for engaging with the mating pipe. The resin tube has a multilayered construction including an inner fuel barrier layer and an outer layer covered with a protective layer. The outer layer has a small outer diameter (od) up to 6 mm, the fuel barrier layer and the outer layer have a wall-thickness (t), and a ratio of the outer diameter (od)/the wall thickness (t) is in a range of 4 to 8.

1 . A piping unit arranged between an engine and a fuel tank for transporting a fuel, comprising: 
 a resin tube as an essential element for the piping unit,    a connector attached to an end portion of the resin tube for connecting the resin tube to a mating pipe, the connector having a connector body including a retainer holding portion on one end of the connector body along an axial direction and a tube connecting portion on the other end of the connector body along the axial direction for connecting to the resin tube, a retainer held in or on the retainer holding portion for engaging with the mating pipe to securely fix the connector body in an axial direction, and a sealing member contacting air tightly with an outer peripheral surface of the mating pipe to provide a seal between the connector body and the mating pipe,    wherein the resin tube has a multilayered construction including an inner fuel barrier layer and an outer layer made of polyamide covered further with a protective layer on an outer peripheral surface of the outer layer, the resin tube inside the protective layer has a small outer diameter (od) up to 6 mm and a wall-thickness (t), a ratio of the outer diameter (od) of the resin tube/the wall thickness (t) of the resin tube is in a range of 4 to 8.    
   
   
       2 . The piping unit as set forth in  claim 1 , wherein the retainer holding portion is in a form of a socket shape.  
   
   
       3 . The piping unit as set forth in  claim 1 , wherein the fuel barrier layer is made of ethylene-tetrafluoroethylene.  
   
   
       4 . The piping unit as set forth in  claim 1 , wherein a main constituent of the fuel barrier layer is a material selected from a group consisting of ethylene-tetrafluoroethylene, thermoplastic polyester elastomer, polybutylene terephtharate, polybutylene naphthalate, polyphenylene sulfide, polyethylene, polypropylene, polyvinylidene fluoride, and polyethylene vinyl alcohol.  
   
   
       5 . The piping unit as set forth in  claim 1 , wherein the resin tube is attached to the connectors at both end portions of the resin tube by force-fitting or solvent welding.  
   
   
       6 . The piping unit as set forth in  claim 1 , wherein a checker member is formed or mounted in or on the connector, the checker member is configured disengageable from the connector when the mating pipe is connected to the connector correctly.  
   
   
       7 . The piping unit as set forth in  claim 1 , wherein a closing member is mounted in the connector for closing a connecting opening through which the mating pipe is inserted in the connector before the mating pipe is connected to the connector.  
   
   
       8 . The piping unit as set forth in  claim 1 , wherein the piping unit is used for piping in a returnless fuel system in which the fuel is supplied from the fuel tank to an injector of the engine, but is not returned from the injector to the fuel tank.