A revolutionary new system for producing plastic fuel tanks
is the grand winner of the 38th annual Automotive
Innovation Awards Competition held by the Society of Plastics Engineers (SPE).
The twin-sheet blow molding system (TSBM) developed by Inergy Automotive Systems
integrates components into a fuel tank during blow molding, reducing costs and
emissions at the same time.
"This technology is the gateway to the next generation of
plastic fuel systems, allowing much more complex fuel systems that met the
strictest of performance and emissions standards," says Dave Hill, project
engineer, Inergy Automotive Systems of Adrian, MI.
In the new process already in use in the BMW AG Series, sheets extrude between a
central core and a mold. Core actions attach the components during initial
sheet forming. The empty core is
withdrawn and the mold is closed to join the formed sheets in a second blowing
step. 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 requires
boring and welding of externally mounted components. "Weight savings are up to
10 percent compared to conventional blow molding," says Hill. "The Twin-Sheet
Blow Molding process allows improved wall thickness control." There's an
additional 10 percent savings through component simplification and reduction in
"More internal components mean fewer potential fuel leak
paths," adds Hill. "Increased design flexibility provides increased tank
capacity and driving range." Placing baffles within the tank also reduce noise.
Possibly most significantly, the internal placement of
components also reduces emissions. "Permeation of the fuel system can be
dramatically reduced compared to current tank systems at the same or lower
cost," says hill. "The technology can meet all global evaporative emission
The most important standard right now is in California, which is requiring
vehicles to reduce their fuel emission by a factor of ten, to fewer than 54 mg
per vehicle per day.
The key to the technology is the in-mold assembly. "We
designed the tool so that it can be used with conventional blow molding
machines," says Hill. Components are integrated using one of two innovative
technologies. Internal welding is used for small components and internal
riveting is used for larger components. Parts up to one kilogram can be
inserted into the parison. The process also allows attachment of non-compatible
materials, such as polyacteal to polyethylene.
The materials suppliers who participated in the technology
development are Lyondell Basell, HDPE; Kurray, the EVOH barrier; and Mitsui for
Inergy is expecting to sell up to 3.4 million units of its
system in2012 and will do so by increasing by half the number of new markets,
in particular in Asia where its strategic
clients are concentrated. Inergy is a 50/50 joint venture between Plastic Omnium and Solvay SA, and is a leading global Tier One supplier of complete
plastic fuel systems and fluid storage technologies. It's headquartered in Paris and has 25
facilities located in 19 countries. In 2007, Inergy delivered 12.7 million fuel
Other winners are:
Exterior category: An integrated
rocker molding/running board system used in the Ford Escape SUV
Body Interior category: An integrated floor shifter / front console used in the
Injection molded oil pan for the Daimler AG C Class vehicles.
Soy foam automotive seat cushions for the Ford Mustang. Ford Mustang.
Thermoplastic elastomer for slush molding of instrument panel skins in the
Saab 9-7X SUV.
& Customization: Hood assembly with dual-weave carbon fiber composite
in the Chevrolet Corvette ZR1 Sports Car.
Technologies: A twin-sheet blow-molded fuel system in the BMW 7 series
sedans. Also the grand prize winner.
Polystyrene foam for head-impact protection in the Ford Focus.
Note: Design News
Contributing Editor Doug Smock served as a member of the Blue Ribbon Judging
Panel for the SPE Automotive design competition.