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Examination on Fuel Leakage Mechanism of LPi Vehicle to Meet the ULEV Regulation
Published October 22, 2006 by Society of Automotive Engineers of Japan in Japan
Liquid Phase LPG injection (LPi) system has several advantages of precise fuel metering and higher engine performance comparing to those of conventional mixer system. However leakage problem of LPi system at the injector tip is a main obstacle for meeting more stringent future emission regulations because it produces excessive amount of THC emission during cold and hot restart phase. The main focus of this paper is the development of leakage fuel recirculation system with activated carbon canister to eliminate the leaked fuel at intake system. The leaked fuel level was quantified using Fast Response Flame Ionization Detector (FRFID). Finally, to confirm the adsorption efficiency of recirculation system in LPi vehicle, THC emission level is measured through the phase 1 of FTP-75 mode. The result of vehicle test that duty control makes stable engine operation with various operation engine condition and recirculation system is an effective method to meet the SULEV standard of the LPi engine.