Abstract
Keywords - ETFE, PZEV, fuel hose, evaporative emission, fuel permeation
Abstract - In response to ever-growing environmental concerns, authorities in North America, Europe, and Japan are tightening regulations on fuel evaporation. Mitsubishi Motors
Corporation developed and now produces PA12/ETFE multi-layer resin fuel hoses to meet
California LEV I and Federal Tier-1 Regulations. However, the more stringent LEV II regulation came into effect in the 2004 Model Year.
We therefore successfully developed the world's first fuel and vapor hoses made solely of ETFE fluoride resin to achieve superior fuel barrier performance to earn ZEV (zero emission vehicle) credit s on gasoline vehicles as PZEVs (partial zero emission vehicles). The fuel barrier performance of the new single-layer hoses is twice as high as that of PA12/ETFE multi-layer resin hoses, and the new hoses are also highly resistant to combustion and chemicals. New hoses comprised solely of hard-to-deteriorate ETFE resin will also make it easier to recycle in-process scraps.
The new hoses consist of a resin tube and quick connectors, so we considered the performance of quick connectors as well as a resin tube. We reduced the evaporation by replacing the copolymer fluorocarbon rubber O-rings with terpolymer ones. We also reinforced the tube fixing with a resin sleeve, because the new tube came out of the quick connectors more easily than PA12/ETFE multi-layer hoses at high temperatures due to the high-temperature dynamics properties of ETFE resin.
Fuel hoses of 6 mm I.D. and 8 mm O.D. can be made by bending straight-extruded tube at high temperature. Larger-diameter vapor hoses of 13 mm I.D. and 15.5 mm O.D., however, require a corrugated construction in order to be bent when forming.
We introduced the new hoses in our PZEV vehicles after confirming their applicability through various endurance and reliability tests.