Method and system for controlling water injection

Abstract

The invention discloses a method and system for controlling water injection. Methods and systems are provided for synergizing the benefits of engine water injection in a hybrid vehicle system. Duringengine operation, in response to a change in a driver demand, the controller may opt to switch between water injection states while using stored power assist. The selection may be based on the combination of water injection and stored power offset that provides the highest engine efficiency.

Description

technical field [0001] The present description generally relates to methods and systems for controlling water usage of an engine coupled in a vehicle having a hybrid transaxle and an energy storage system. Background technique [0002] Internal combustion engines may include water injection systems that inject water into various locations, such as into the intake manifold upstream of the engine cylinders, or directly into the engine cylinders. Engine water injection provides various benefits, such as increased fuel economy and engine performance, and reduced engine emissions. In particular, when water is injected into the engine intake or cylinders, heat is transferred from the intake and / or engine components to evaporate the water, resulting in charge cooling. Injecting water into the intake air (eg, into the intake manifold) reduces the temperature of the intake air as well as the temperature of combustion at the engine cylinders. By cooling the intake charge, the tenden...

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Problems solved by technology

Another problem is that frequent changes in the operator's pedal demand can cause the engine load to shift back and forth, causing the water injection to turn on and off frequently

Excessive switching reduces fuel economy due to losses incurred during transitions and can reduce component life

In addition, frequent switching can cause speed / load and air-fuel ratio disturbances

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