Varied intake valve operation for improved transient response in gaseous fuel engine

An engine system comprising:

• an engine including an engine housing forming a cylinder, an intake port arranged to feed a flow of intake air to the cylinder, an intake valve movable to open and close the intake port, and a piston movable in the cylinder;
• a fuel system including a gaseous fuel supply, and a fuel injector fluidly connected to the gaseous fuel supply and arranged to inject a gaseous fuel to mix with the flow of intake air for combustion in the cylinder;
• a cam coupled to the intake valve and rotatable to move the intake valve between a closed position and a fully open position;
• a variable valve actuator coupled to the intake valve;
• and
• a control device structured to operate the variable valve actuator in an engine cycle to cause the intake valve to move from the closed position to flow-throttling middle position between the closed position and the fully open position, and to move from the flow-throttling middle position back to the closed position.

A method of operating an engine system comprising:

• positioning an intake valve at a fully open position in an engine;
• admitting a flow of intake air past the fully open intake valve into a cylinder in the engine;
• combusting a gaseous fuel mixed with the intake air admitted past the fully open intake valve in the cylinder in a first engine cycle;
• positioning the intake valve at a partly open position;
• admitting a throttled flow of intake air past the partly open intake valve into the cylinder;
• moving the intake valve from the partly open position to a closed position;
• and
• combusting the gaseous fuel with the intake air admitted past the partly open intake valve in a second engine cycle.