Methods and systems for engine braking with reduced noise, vibration, and harshness
AssigneeFord Global Technologies, LLC
InventorDouglas Martin
Life of this patent
Estimating the term…
Abstract
Methods and systems are provided for engine braking in a vehicle. In one example, a method may include, in response to an engine braking request: deactivating fueling to at least one engine cylinder, decreasing an effective flow area of a turbine inlet of a variable geometry turbocharger (VGT), and adjusting an intake valve of the at least one engine cylinder based on a requested braking torque of the engine braking request and the effective flow area of the turbine inlet. In this way, increased exhaust backpressure may be generated to increase engine pumping losses while the intake valve adjustment increases in-cylinder pumping losses, thereby increasing an amount of engine braking torque.
Claims20
A method, comprising:
- responsive to an engine braking request:
- deactivating fueling to at least one cylinder of an engine;
- decreasing an effective flow area of a turbine inlet of a variable geometry turbocharger (VGT);
- and
- adjusting an intake valve of the at least one cylinder based on a requested braking torque of the engine braking request and the effective flow area of the turbine inlet, including determining an amount of braking torque generated by decreasing the effective flow area of the turbine inlet, and further closing the intake valve as a difference between the determined amount of braking torque generated by decreasing the effective flow area of the turbine inlet and the requested braking torque of the engine braking request increases.
(canceled)
A method, comprising:
- during an engine braking event in an engine:
- discontinuing combustion in the engine;
- generating a first portion of a requested braking torque of the engine braking event by decreasing a cross-sectional area of an inlet of an exhaust turbine;
- and
- generating a second portion the requested braking torque by closing intake valves of the engine by an amount determined based on the requested braking torque and the first portion, including fully closing the intake valves throughout an engine cycle responsive to the requested brake torque being greater than a non-zero, brake threshold above which maximum engine braking is desired.
A system, comprising:
- an engine including a plurality of cylinders, each of the plurality of cylinders including an intake valve and an exhaust valve each controlled via a continuously variable valve lift (CVVL) system;
- a variable geometry turbocharger (VGT) including a turbine coupled to an exhaust passage of the engine;
- and
- a controller including instructions stored in non-transitory memory that, when executed, cause the controller to:
- provide engine braking by adjusting an inlet geometry of the turbine to a further closed position, discontinuing combustion in a number of the plurality of cylinders, and adjusting both of the intake valve and the exhaust valve of each of the number of the plurality of cylinders via the CVVL system in response to a requested braking torque for the engine braking, including in response to additional noise reduction being desired, holding the exhaust valves open while the piston travels from bottom dead center to top dead center and otherwise holding the exhaust valve closed.
Dependencies are inferred from the claim text.