Work on several innovative designs and materials is underway for vehicle fuel tank systems, as this is an area that is coming under increasing pressure from legislation, particularly in the United States to withstand stronger impacts without leaking. The main factors driving fuel tank innovation are legislation, weight, packaging, safety and cost. Along with a continued demand for fuel tank range and fuel economy, more complex shapes and geometries are being seen, particularly driven by the all/rear wheel drive increase in smaller car segments.
In the 1970s, all fuel tanks were made of steel. In todays' scenario, an estimated 85% of newly registered vehicles in Europe are equipped with plastic tanks while over 70% of cars built for North American roads have plastic tanks, a material chosen for its proven resistance to corrosion, light weight and ease of moulding into unusual shapes. They are increasingly being manufactured with their major components sealed inside the tank. While the angular shape of modern plastic fuel tanks may appear a little strange, their blow-moulded design allows maximum fuel holding capacity in a minimum amount of space. They are also considered more 'crashworthy' because of their seamless design and ability to deform. just-auto estimates that the total tonnage of steel lost in 2006 to plastic fuel tanks was nearly 348,000 tons, and that figure could reach 419,000 tons by 2013. And the trend in favour of plastic fuel tanks will continue to grow until the market is saturated.
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 could produce plastic fuel systems with more complex designs that will meet the strictest of performance and emissions standards. In the new process already in use in the BMW AG Series, sheets are extruded 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 The empty core is withdrawn and the mold is closed to join the formed sheets in a second blowing step.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 could go up by 10% compared to conventional blow molding. The Twin-Sheet Blow Molding process allows improved wall thickness control. There is an additional 10% savings through component simplification and reduction in finishing costs. 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/day. The material suppliers who participated in the technology development are Lyondell Basell, HDPE; Kurray, the EVOH barrier; and Mitsui for the adhesive. Inergy expects to sell up to 3.4 million units of its system in 2012 and will do so by increasing by sales in new markets, in particular in Asia where its strategic clients are concentrated.
As per just auto, until the implementation of the LEV1 legislation in the US , blow-moulded monolayer fluorinated fuel tanks were the preferred technology in the US market. However, the long-term performance of the fluorinated tanks was a major concern at the time. In addition, the fluorination process was relatively difficult and used hazardous chemicals. As a result, new barrier technologies were introduced. The development of the slosh test in the US led to the use of six-layer fuel tanks. In Europe , however, fluorination is still popular because manufacturers can use their monolayer machines with these technologies and do not need to invest in new equipment. In Japan , three-material, five-layer plastic fuel tanks using nylon as a barrier resin have been used for more than 15 years. Although multilayered plastic certainly appears to have become the material of choice for automakers, there are still some concerns over its recyclability.
|
|