Method and system for controlling water injection

Abstract

The application provides a method and a system for controlling water injection. Methods are provided for optimizing usage of water from a water injection system that injects water into the engine responsive to engine operating conditions such as knock, exhaust temperature, and dilution demand. An amount of water selected for injection purposes, as well as an order of water injection responsive tothe various engine operating conditions, is varied based on a current water level relative to a predicted future water level. The method allows water usage benefits to be maximized particularly when water availability is limited.

Description

technical field [0001] The present description generally relates to methods and systems for prioritizing water usage in an engine. Background technique [0002] Internal combustion engines may include a water injection system that injects water into various locations, such as injecting water into the intake manifold upstream of the engine cylinders, or injecting water directly into the engine cylinders. Engine water injection provides various benefits such as increases in fuel economy and engine performance and reductions in engine emissions. Specifically, when water is injected into the engine intake or cylinders, heat is transferred from the intake air and / or engine components to evaporate the water, resulting in charge intercooling and engine dilution. Injection of water into the intake air (eg, in the intake manifold) reduces intake air temperature and combustion temperature at the engine cylinders. By cooling the intake charge, the tendency to knock can be reduced wit...

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Additionally, greater volumetric efficiency can result in increased torque

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