Innovative Fuel Tank Wins SPE's Grand Auto Design Prize

A revolutionary new system for producing plastic fuel tanksis the grand winner of the 38th annual AutomotiveInnovation Awards Competition held by the Society of Plastics Engineers (SPE).

The twin-sheet blow molding system (TSBM) developed by Inergy Automotive Systemsintegrates components into a fuel tank during blow molding, reducing costs andemissions at the same time.

"This technology is the gateway to the next generation ofplastic fuel systems, allowing much more complex fuel systems that met thestrictest of performance and emissions standards," says Dave Hill, projectengineer, Inergy Automotive Systems of Adrian, MI.

In the new process already in use in the BMW AG Series, sheets extrude between acentral core and a mold. Core actions attach the components during initialsheet forming.  The empty core iswithdrawn and the mold is closed to join the formed sheets in a second blowingstep. Components that can be attached to the core include baffles, gauges,valves, jet pumps, lines, fuel modules, and canisters.

TSBM replaces co-extrusion blow molding, which requiresboring and welding of externally mounted components. "Weight savings are up to10 percent compared to conventional blow molding," says Hill. "The Twin-SheetBlow Molding process allows improved wall thickness control." There's anadditional 10 percent savings through component simplification and reduction infinishing costs.

"More internal components mean fewer potential fuel leakpaths," adds Hill. "Increased design flexibility provides increased tankcapacity and driving range." Placing baffles within the tank also reduce noise.

Possibly most significantly, the internal placement ofcomponents also reduces emissions. "Permeation of the fuel system can bedramatically reduced compared to current tank systems at the same or lowercost," says hill. "The technology can meet all global evaporative emissionstandards."

The most important standard right now is in California, which is requiringvehicles to reduce their fuel emission by a factor of ten, to fewer than 54 mgper vehicle per day.

The key to the technology is the in-mold assembly. "Wedesigned the tool so that it can be used with conventional blow moldingmachines," says Hill. Components are integrated using one of two innovativetechnologies. Internal welding is used for small components and internalriveting is used for larger components. Parts up to one kilogram can beinserted into the parison. The process also allows attachment of non-compatiblematerials, such as polyacteal to polyethylene.

The materials suppliers who participated in the technologydevelopment are Lyondell Basell, HDPE; Kurray, the EVOH barrier; and Mitsui forthe adhesive.

Inergy is expecting to sell up to 3.4 million units of itssystem in2012 and will do so by increasing by half the number of new markets,in particular in Asia where its strategicclients are concentrated. Inergy is a 50/50 joint venture between Plastic Omnium and Solvay SA, and is a  leading global Tier One supplier of completeplastic fuel systems and fluid storage technologies. It's headquartered in Paris and has 25facilities located in 19 countries. In 2007, Inergy delivered 12.7 million fuelsystems.

Other winners are:

Note: Design NewsContributing Editor Doug Smock served as a member of the Blue Ribbon JudgingPanel for the SPE Automotive design competition.