Venturi tube for steam purge

Abstract

This invention relates to venturi tubes for steam purging. Systems and methods are provided for an engine including a venturi connected in an engine intake system. In one example method, a method of controlling operation of an engine having a fuel vapor purge system includes directing intake air through a first throttle valve and a venturi arranged in a bypass line at connecting upstream and downstream of a second throttle valve in the intake duct adjacent to the engine intake duct; and delivering a flow of fuel vapor from the fuel vapor purge system to the inlet of the venturi in response to operating conditions.

Description

Background technique

[0001] Evaporative emissions control systems capture fuel vapors in an activated carbon canister, such as when parked, and then burn the vapors in the engine when the vehicle is running. In some approaches, the vacuum created in the engine intake manifold is used to pull air through the activated carbon canister to purge the fuel therein. In some examples, such fuel vapor purging systems may be used in engines that include features for increasing fuel economy, such as via variable camshaft timing, variable valve lift, engine downsizing (e.g. EcoBoost) and (e.g. in Hybrid Electric Vehicles (HEV)) hybridization and more.

[0002] However, this method of increasing fuel economy reduces the amount of vacuum in the intake manifold, and / or reduces the frequency at which vacuum is available, thus reducing the amount of vacuum available to purge fuel vapors from the fuel vapor purge system . Also, in some examples, if more purge vacuum is required in this appro...

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