Method for manufacturing a plastic fuel tank with improved creep strength

Abstract

A method for manufacturing a plastic fuel tank including: a) inserting a plastic parison including two distinct parts into an open two-cavity mold; b) inserting a core, bearing at least part of a reinforcing element configured to create a link between the two parison parts, inside the parison; c) pressing the parison firmly against the mold cavities, for example by blowing through the core and/or creating suction behind the cavities; d) fixing the part of the reinforcing element to at least one of the parison parts using the core; e) withdrawing the core; f) closing the mold, bringing its two cavities together to grip the two parison parts around their periphery to weld them together; g) injecting a pressurized fluid into the mold and/or creating a vacuum behind the mold cavities to press the parison firmly against the mold cavities; and h) opening the mold and extracting the tank.

1 - 13 . (canceled) 
     
     
         14 . A method for manufacturing a plastic fuel tank with improved creep strength, comprising:
 a) inserting a plastic parison including two distinct parts into an open two-cavity mold;   b) inserting a core inside the parison, the core bearing at least part of a reinforcing element configured to create a link between the two parts of the parison;   c) pressing the parison firmly against the mold cavities, or blowing through the core and/or creating suction behind the cavities;   d) fixing at least a part of the reinforcing element to at least one of the parts of the parison using the core;   e) withdrawing the core;   f) closing the mold again, bringing its two cavities together so as to grip the two parts of the parison around their periphery to weld them together;   g) injecting a pressurized fluid into the mold and/or creating a vacuum behind the mold cavities to press the parison firmly against the mould cavities; and   h) opening the mold and extracting the tank.   
     
     
         15 . The method according to  claim 14 , wherein the tank is molded by injecting a pressurized fluid into the mold, and wherein the parison is made of two separate parts resulting from cutting an extruded cylindrical parison. 
     
     
         16 . The method according to  claim 14 , wherein the tank is molded by creating a vacuum behind the mold cavities, and wherein the parison is made of two extruded sheets. 
     
     
         17 . The method according to  claim 14 , wherein the core includes a hydraulic ram that fixes the reinforcing element to the parison. 
     
     
         18 . The method according to  claim 14 , wherein the reinforcing element is a functional element of the tank, and wherein only a support of the reinforcing element is introduced into the tank at a time of molding, the functional element itself being introduced into the tank after being released from the mold through an opening made in the wall of the tank. 
     
     
         19 . The method according to  claim 18 , wherein the functional element is a pump/gauge module. 
     
     
         20 . The method according to  claim 14 , wherein the reinforcing element includes at least one rod. 
     
     
         21 . The method according to  claim 20 , wherein the rod is made from waste from production of similar tanks. 
     
     
         22 . The method according to  claim 20 , wherein the rod is made in two parts equipped with a clip-fastening device, wherein the parts, not clip-fastened to one another, are fixed facing one another on a part of the parison each, and wherein shrinkage of the tank after release from the mold is enough for the two parts to clip-fasten of their own accord and/or external pressure is applied to the walls of the tank to perform/enhance the clip-fastening. 
     
     
         23 . The method according to  claim 14 , wherein the welding f) generates a welded seam that is partially removed so as to leave pads or lugs for attaching the tank to a motor vehicle chassis. 
     
     
         24 . A plastic fuel tank comprising:
 a lower wall and an upper wall that are assembled by welding; and   at least one rod situated inside the tank and connecting its lower wall to its upper wall.   
     
     
         25 . A plastic fuel tank comprising:
 a lower wall and an upper wall assembled by welding; and   at least one functional element situated inside the tank and connecting its lower wall to its upper wall.   
     
     
         26 . A plastic fuel tank comprising:
 a lower wall and an upper wall assembled by welding; and   at least one reinforcing element situated inside the tank and connecting its lower wall to its upper wall,   the welding connecting the walls being extended by a welded seam that is interrupted in places to form lugs so that the tank can be fixed to a motor vehicle chassis.