System and method for variable compression ratio engine
AssigneeFord Global Technologies, LLC
InventorsFabian Gadau, Christopher Glugla
Life of this patent
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Abstract
Methods and systems are provided for maintaining a compression ratio of an engine via a brake and while disabling an electric current applied to an actuator of the associated variable compression ratio mechanism. A braking force applied via the brake on a compression ratio control shaft is varied before and during a compression ratio transition to move the control shaft at a desired velocity. Brake torque application is coordinated with motor torque from a VCR actuator and engine torque applied on the control shaft to enable a smooth CR transition.
Claims19
A method for an engine, comprising:
- maintaining a position of a control shaft for varying a compression ratio of an engine via braking force from a brake;
- adjusting the braking force prior to and during actuation of the control shaft based on operating conditions;
- and
- actuating the control shaft responsive to an upcoming transmission shift, a transmission shift schedule adjusted based on the braking force.
A method for an engine, comprising:
- during a first condition, when outside a threshold compression ratio range, maintaining a fixed position of a control shaft that varies a compression ratio of an engine via braking force from a brake;
- and
- during a second condition, when inside the threshold compression ratio range, continuously varying a position of the control shaft within a position range via the braking force.
An engine system, comprising:
- an engine;
- a control shaft for varying a compression ratio of the engine;
- a brake for applying a brake torque on the control shaft, the brake actuated via a spring-loaded solenoid valve;
- an electrical actuator for applying a motor torque on the control shaft;
- a transmission including a plurality of gears;
- and
- a controller storing executable instructions in non-transitory memory that, when executed, cause the controller to:
- maintain the control shaft in a fixed position via the brake to maintain a first compression ratio setting of the engine;
- responsive to a request to transition the engine to a second compression ratio setting, lower than the first setting;
- and
- adjust a ratio of the brake torque from the brake and the motor torque from the electrical actuator on the control shaft as a function of engine torque applied on the control shaft due to cylinder combustion.
Dependencies are inferred from the claim text.