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International Journal of Automotive Technology 2008;9(5): 543-549. |
| TRANSIENT CHARACTERISTICS OF EMISSIONS DURING ENGINE START/STOP OPERATION EMPLOYING A CONVENTIONAL GASOLINE ENGINE FOR HEV APPLICATION |
| S. YU1, G. DONG2, L. LI2 |
1Shanghai Jiao Tong University
2Tongji University |
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| ABSTRACT |
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The transient characteristics of combustion and emissions during the engine start/stop operation in hybrid electric vehicle (HEV) applications are investigated in this paper. Hydrocarbon (HC) emissions during the initial 2nd~9th cycles was found being deteriorated significantly when the engine is quickly started under the original engine calibration mode. Lower intake manifold absolute pressure (MAP) was also found to cause larger residual gas dilution and poor combustion resulting in a higher HC concentration when the cranking speed was increased. The post-catalyst HC concentration was measured to initially decrease and then increase again as the cranking speed was increased. A lowest concentration value was achieved at cranking speed of 1000r/min. Engine shut-down by fuel cut-off can avoid misfire of the last fuel injection, therefore, less HC emissions are emitted during stop process compared with the shut-down process by ignition cut-off. The fuel deposit during stop process seems to impact engine restart enrichment mostly at the initial 0.7s for this engine, which is dominated by the MAP transition characteristic and the time coefficient for fuel vaporization. |
| Key Words:
Hybrid Electric Vehicle, Start /Stop, Transient Emission Characteristics |
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