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A LOW EMISSION ENGINE STARTING STRATEGY FOR START/STOPS

IP.com Disclosure Number: IPCOM000240460D
Publication Date: 2015-Jan-30
Document File: 1 page(s) / 244K

Publishing Venue

The IP.com Prior Art Database

Abstract

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A LOW EMISSION ENGINE STARTING STRATEGY FOR START/STOPS

Vehicles sold in North America are required to adsorb diurnal, running loss and refueling vapors inside a carbon canister. Hydrocarbon (HC) vapors contribute to SMOG and it is undesirable to emit them into the atmosphere. The canister is typically cleaned or purged using engine vacuum during combustion. A Canister Purge Valve (CPV) is ramped open to purge the canister. Hybrid Electric (HEV) and Start/Stop vehicles utilize a special Vapor Blocking Valve (VBV) to improve purge efficiency. This is due to limited engine run time in those vehicles. While purging, the VBV is commanded closed. This way, the canister is cleaned out without further loading with vapors from the fuel tank. At key off, the VBV is typically open and the Evap system is vented to atmosphere. Cold Start Emissions is a major source of hydrocarbon emissions into the atmosphere. During cold starts, the catalyst is still not warm yet and hence hydrocarbons escape into the atmosphere. During cold starts, software controls typically retard the spark to generate heat and warm up the catalyst quickly. The warm up process takes 15-30 seconds. Up to 80% of HC tailpipe emissions during a drive cycle occurs during a cold start since raw liquid fuel does not burn thoroughly. Liquid Fuels do not vaporize readily in cold climates. This is aggravated even more if the fuel is summer grade.

Method

We alleviate cold start HC emission problems by utilizing HC...