A control system for an engine including intake and exhaust valve phase variable devices and a control device is provided. At an engine temperature below a first determination temperature, the control is performed so that an exhaust valve close timing is at or retarded from the exhaust top dead center, an intake valve open timing is retarded from the exhaust valve close timing, and the fuel supply to the combustion chamber starts in an intake stroke on a retarding side of the exhaust valve close timing. At the engine temperature above the first determination temperature and below a second determination temperature, the control is performed so that a negative overlap with both the exhaust and intake valves closed during a period including the exhaust top dead center, or a positive overlap with both the exhaust and intake valves opened during a period including the exhaust top dead center, occurs.

An engine system is provided, including a controller which estimates an intake-valve-closing temperature inside a cylinder. When an engine operates at a given speed and a demanded engine load is a first load or a second load (>the first load), the controller controls so that a mixture gas inside the cylinder combusts by compression ignition, and controls so that, at the first load, the entire mixture gas combusts by compression ignition when the intake-valve-closing temperature is above a first temperature, and at least part of the mixture gas combusts by flame propagation when the intake-valve-closing temperature is below the first temperature, whereas at the second load, the entire mixture gas combusts by compression ignition when the intake-valve-closing temperature is above a second temperature (<the first temperature), and at least part of the mixture gas combusts by flame propagation when the intake-valve-closing temperature is below the second temperature.

A system and method of controlling a cylinder deactivation mechanism can comprise executing a valve lift event configured to lift a valve via a rocker arm. The rocker arm can be configured with a controllable latch in a latched condition, wherein the controllable latch is configured with an edge that is clamped in a recess in the rocker arm during the valve lift event, a clamp force supplied in part by pressure from the valve lift event. A deactivation signal can be sent to select the unlatched condition to collapse the controllable latch from the recess while the controllable latch is configured in the valve lift event with the edge clamped in the recess. A subsequent valve lift event can have actuation deactivated by collapsing the controllable latch from the recess once the valve lift event is complete and the clamp force is removed.

An internal combustion engine includes: a fuel injection valve injecting fuel; an intake timing varying mechanism controlling the opening/closing of an intake valve provided at an intake port; and an exhaust timing varying mechanism controlling the opening/closing of an exhaust valve provided at an exhaust port. When a request has been made to reduce a fuel wet amount, which is a quantity of fuel adhering to a wall surface of the internal combustion engine facing to an injection field where fuel is injected, in the startup of the internal combustion engine, the control device executes wet reduction control. In the wet reduction control, at least one of the intake timing varying mechanism or the exhaust timing varying mechanism is controlled so as to reduce the fuel wet amount by a counterflow blowing back toward the intake port.

Methods and systems are described for combustion engine mode optimization. The system includes a combustion engine, a fuel delivery system, and a controller communicatively coupled to the combustion engine and the fuel delivery system. The controller selects a low temperature combustion mode based on the combustion engine being warmer than a predetermined temperature and low load conditions on the combustion engine. The low temperature combustion mode includes instructions that reduces an intake valve opening duration and an exhaust valve opening duration. The controller reduces the intake valve opening duration and the exhaust valve opening duration to create a delay between an intake valve opening duration and an exhaust valve opening duration in response to selecting the low temperature combustion mode. The delay increases a residual gas temperature in the combustion chamber and induces auto-ignition of fuel in the combustion chamber.

A combustion mode module is configured to switch operation of a low-temperature combustion (LTC) engine between a spark ignition (SI) mode, a positive valve overlap (PVO) mode, and a negative valve overlap (NVO) mode. A spark control module is configured to control a spark plug to generate a spark in a cylinder of the LTC engine when the LTC engine is operating in the SI mode. A valve control module is configured to control intake and exhaust valves of the cylinder to yield a PVO and a NVO when the LTC engine is operating in the PVO mode and the NVO mode, respectively. An air/fuel (A/F) control module is configured to adjust a desired A/F ratio of the LTC engine to a rich A/F ratio when operation of the LTC engine is switched to the PVO mode from either one of the SI mode and the NVO mode.

A combustion mode module is configured to switch operation of a low-temperature combustion (LTC) engine between a spark ignition (SI) mode, a positive valve overlap (PVO) mode, and a negative valve overlap (NVO) mode. A spark control module is configured to control a spark plug to generate a spark in a cylinder of the LTC engine when the LTC engine is operating in the SI mode. A valve control module is configured to control intake and exhaust valves of the cylinder to yield a PVO and a NVO when the LTC engine is operating in the PVO mode and the NVO mode, respectively. An air/fuel (A/F) control module is configured to adjust a desired A/F ratio of the LTC engine to a rich A/F ratio when operation of the LTC engine is switched to the PVO mode from either one of the SI mode and the NVO mode.

The disclosure concerns variable valve timing of a four-stroke ICE. The ICE comprises: an exhaust valve and an intake valve an exhaust camshaft an intake camshaft and a cylinder arrangement. The cylinder arrangement comprises a combustion chamber a cylinder bore and a piston. The control arrangement is configured to: perform a first sequence of changes in the timings of the exhaust and intake camshafts in order to arrive from a first camshaft timing setting at a second camshaft timing setting based on a first current maximum cylinder pressure within the combustion chamber around top dead centre fire and/or around to dead centre gas exchange.

Methods and systems for unsticking a stuck gaspath actuator are disclosed. In one embodiment, an engine operating method includes adjusting exhaust valve timing of one or more cylinders of an engine in response to an indication that a gaspath actuator is stuck in position. In this way, pressure waves in an exhaust manifold and/or an intake manifold may be generated, which may act to unstick the gaspath actuator.

A control system for an engine including intake and exhaust valve phase variable devices and a control device is provided. At an engine temperature below a first determination temperature, the control is performed so that an exhaust valve close timing is at or retarded from the exhaust top dead center, an intake valve open timing is retarded from the exhaust valve close timing, and the fuel supply to the combustion chamber starts in an intake stroke on a retarding side of the exhaust valve close timing. At the engine temperature above the first determination temperature and below a second determination temperature, the control is performed so that a negative overlap with both the exhaust and intake valves closed during a period including the exhaust top dead center, or a positive overlap with both the exhaust and intake valves opened during a period including the exhaust top dead center, occurs.