Method and system for controlling water injection
AssigneeFord Global Technologies, LLC
InventorsThomas G. Leone, Kenneth James Miller
Life of this patent
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Abstract
Methods and systems are provided for synergizing the benefits of engine water injection in a hybrid vehicle system. During engine operation, in response to a change in 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.
Claims20
A method for a hybrid vehicle including an engine configured with water injection and a hybrid transaxle (MHT), comprising:
- for a desired power level, comparing a first fuel economy without water injection and a first amount of stored power offset from an energy storage system to a second fuel economy with water injection at a first adjusted engine speed-load and a second amount of stored power offset;
- responsive to the second fuel economy exceeding the first fuel economy, and a higher than threshold water availability, injecting an amount of water into the engine and changing to the first adjusted engine speed-load;
- and
- responsive to the first fuel economy exceeding the second fuel economy or a lower than threshold water availability, operating the engine without water injection, and changing the engine speed-load to a second adjusted engine speed-load.
A method for a hybrid vehicle, comprising:
- propelling the vehicle via an engine operating with a water injection state selected based on driver demand and water availability on-board the vehicle;
- and
- in response to a change in driver demand, adjusting the water injection state based on each of the change in driver demand, a state of charge of an energy storage system, and the water availability.
A vehicle system, comprising:
- an engine;
- a motor powered via an energy storage system;
- a fuel injector for delivering fuel from a fuel tank to the engine;
- a water injector for delivering water from a water reservoir to the engine;
- a modular hybrid transaxle (MHT) coupling the engine and the motor to vehicle wheels, the MHT having a plurality of speed ratios;
- and
- a controller with computer readable instructions stored on non-transitory memory for:
- estimating a first efficiency associated with operating the engine with the water injector deactivated and a first power offset from the energy storage system;
- estimating a second efficiency associated with operating the engine with the water injector activated and a second, different power offset;
- if the second efficiency is higher than the first efficiency, and a water level in the water reservoir is higher than a threshold, activating the water injector, adjusting an output of the motor to provide the second power offset, and selecting one of the plurality of speed ratios of the MHT to operate the engine with a first modified engine speed-load profile;
- and
- if the second efficiency is lower than the first efficiency, or the water level in the water reservoir is lower than the threshold, deactivating the water injector, adjusting the output of the motor to provide the first power offset, and selecting another one of the plurality of speed ratios of the MHT to provide a second modified engine speed-load profile, different from the first modified engine speed-load profile.
Dependencies are inferred from the claim text.