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US 2018/0001885 A1Published application
Method and system for torque control
AssigneeFord Global Technologies, LLC
InventorsThomas G. Leone, Kenneth James Miller
Life of this patent
Estimating the term…
Abstract
Methods and systems are provided for reducing torque pulsations during hybrid engine shutdown and restarts. A valve actuating mechanism may be actuated to operate an engine with a selected valve lift profile during engine restart and shutdown events that is distinct from the valve lift profile applied during cylinder combustion. The selected valve lift profile reduces cylinder pressure during engine shutdown and restarts.
Claims20
A method for a hybrid vehicle, comprising:
- in response to a hybrid engine shutdown or restart event, actuating a cam actuator while pulling down or pulling up an engine to operate one or both of an intake valve and an exhaust valve of each cylinder according to an adjusted valve lift profile distinct from a unadjusted valve lift profile used during cylinder combustion, the adjusted valve lift profile enabling a lower cylinder compression pressure than the unadjusted valve lift profile;
- and
- selecting the adjusted profile based on a state of charge of an energy storage device.
A method for a hybrid vehicle, comprising:
- during a change from electric mode to engine mode of vehicle operation, operating all valves of each engine cylinder according to a first adjusted valve lift profile before transitioning to a default valve lift profile;
- and
- during a change from engine mode to electric mode of vehicle operation, transitioning from a default valve lift profile to operating all valves of each engine cylinder according to a second, different adjusted valve lift profile, wherein a cylinder compression pressure is lower in each of the first and second adjusted profiles relative to the default valve lift profile.
A hybrid vehicle system, comprising:
- an engine;
- a motor coupled to an energy storage device;
- a cam profile switching mechanism for switching between a plurality of cam profiles, each of the plurality of cam profiles associated with an alternate valve lift profile;
- and
- a controller with computer readable instructions stored on non-transitory memory for:
- in response to an engine restart triggered without input from a vehicle operator,
- cranking the engine with a first of the plurality of cam profiles selected to operate all intake valves and exhaust valves of all engine cylinders with at least a minimum valve lift through all strokes of a cylinder cycle;
- after engine speed is higher than a threshold speed, transitioning to a default valve lift profile to operate all intake valves of all engine cylinders with a fluctuating lift through only an intake stroke of the cylinder cycle, and operate all exhaust valves of all engine cylinders with a fluctuating lift through only an exhaust stroke of the cylinder cycle.
5 more elements
Dependencies are inferred from the claim text.