The pressure buildup that occurs during hybrid-electric and plug-in hybrid-electric vehicle engine-off times will not be problematic for a forthcoming plastic fuel tank.
"In the past, plastic fuel tanks would deflect under high temperature and pressure, which is why OEMs have historically launched hybrid vehicles with heavy steel tanks to withstand the pressure and heat," said Albert Boecker, Director of Advanced Technology – Storage Systems for TI Automotive.
TI's new pressurized tank uses a blow-molding process that "allows for a stiff tank shape that can withstand pressure and temperature over time," Boecker said, adding that the tank provides a 25% weight savings vs. traditional steel or stainless steel solutions for hybrid vehicles.
The in-development tank is made of a six-layer co-extruded plastic.
"TI's tank is comprised of two outer shells and an integrated stiffening skeleton. For higher pressures, a second internal tank is blow-molded inside the shells and skeleton. What is unique about this tank is the skeleton is sandwiched between two tank walls. Today's plastic blow-molded tanks only have a single, fixed-layer wall," said Boecker.
For low-pressure systems up to 150 mbar (2.1 psi) maximum, TI will offer the Stiff Pressurized Tank (SPT), and for higher pressure systems up to 500 mbar (7.3 psi) maximum, a Double Molded Tank (DMT) will be available.
Because the new TI tank's dimensions will be the same as a traditional steel or plastic tank, packaging can be in the same locale as current vehicles, according to Boecker.
TI's production tank is likely to hold 10% less fuel in comparison to a traditional tank.
"The materials are compatible with all types of fuel," according to Boecker. "A prototype tank is under development with European OEMs for a targeted 2013 model year launch."