Method and apparatus for controlling a single-shaft dual expansion internal combustion engine

An internal combustion engine, comprising:

• first and second power cylinders, each including:
• an intake valve;
• a first exhaust valve fluidly coupled to a first runner;
• a second exhaust valve fluidly coupled to a second runner that is fluidly coupled to an exhaust manifold;
• a first variable valve activation system coupled to the intake valves;
• a second variable valve activation system coupled to the first and second exhaust valves and configured to independently control activations of the first exhaust valves and the second exhaust valves;
• an expander cylinder, including:
• an inlet valve fluidly coupled to the first runners;
• an outlet valve fluidly coupled to the exhaust manifold;
• a third variable valve activation system coupled to the outlet valve;
• a controller, operatively connected to the first, second and third variable valve activation systems, the controller including an instruction set executable to command a transition from a bypass mode to an expander mode during engine operation, including:
• control the first variable valve activation system to retard each of the intake valves to a Late Intake Valve Closing (“LIVC”) position;
• control the second variable valve activation system to engage the expander cylinder;
• and then
• control the third variable valve activation system to advance the outlet valve to a maximum advanced state;
• and then
• control the first variable valve activation system to control the intake valves to desired positions associated with engine operation in the expander mode.

A method for controlling an internal combustion engine including first and second power cylinders and an expander cylinder, wherein the internal combustion engine is configured to operate in an expander mode, including exhaust flow from the first and second power cylinders being fluidly coupled to the expander cylinder, and wherein the internal combustion engine is configured to operate in a bypass mode, including exhaust flow from the first and second power cylinders being fluidly decoupled from the expander cylinder;

• the method comprising:
• commanding a transition from the expander mode to the bypass mode during engine operation;
• retarding openings of the intake valves of the first and second power cylinders to a Late Intake Valve Closing (“LIVC”) position;
• retarding the outlet valve of the expander cylinder to a maximum retarded state;
• controlling exhaust valves of the power cylinders to discontinue fluid flow to the expander cylinder;
• controlling, via a controller, the openings of the intake valves of the first and second power cylinders to desired positions associated with engine operation in the bypass mode;
• and
• operating the engine in the bypass mode.