An internal EGR amount calculation device for an internal combustion engine, which is capable of properly and easily calculating an internal EGR amount according to the change in the valve timing and enhancing the calculation accuracy of the internal EGR amount. The device includes an ECU. The ECU calculates an amount of burned gases remaining in a cylinder when the valve timing is predetermined reference timing, as a reference internal EGR amount. The ECU calculates a change in the amount of burned gases flowing into or out of the cylinder with respect to the amount of burned gases flowing into or out of the cylinder when the valve timing is the predetermined reference timing, as an internal EGR increase/decrease amount. Then, the ECU calculates the internal EGR amount by adding the internal EGR increase/decrease amount to the reference internal EGR amount.

Methods and systems for providing vacuum to a vehicle are described. In one example, a method adjusts an engine air-fuel ratio in response to provide additional vacuum to the vehicle.

An internal combustion engine system includes a fuel injection valve, a variable valve operating device and a control device. The control device is configured, where depression of an accelerator pedal is released, to: execute a fuel cut processing to control the fuel injection valve so as to stop fuel injection; and execute an engine braking enhancement processing to control the variable valve operating device so as to advance the opening and closing timings of the exhaust valve compared to during execution of the fuel injection. The engine braking enhancement processing includes a noise reduction processing to adjust at least one of the closing timing of the exhaust valve and the opening timing of the intake valve such that a second compression work associated with compression of in-cylinder gas in an exhaust stroke becomes smaller than a first compression work associated with compression of in-cylinder gas in a compression stroke.

An engine control device is provided, which includes an engine body where a cylinder is formed, an exhaust passage through which exhaust gas discharged from the engine body circulates, a NO.sub.x sensor disposed in the exhaust passage and configured to detect a concentration of NO.sub.x in the exhaust gas, an injector configured to change an air-fuel ratio inside the cylinder, an in-cylinder temperature changer configured to change a temperature inside the cylinder, and a controller configured to control the injector and the exhaust shutter valve. The controller controls the injector based on a detection value of the NO.sub.x sensor to variably set the air-fuel ratio inside the cylinder, and when a particular condition that the air-fuel ratio inside the cylinder is leaner than a preset upper limit is satisfied, and causes the in-cylinder temperature changer to raise the temperature inside the cylinder.

Because an in-cylinder temperature becomes low immediately after cold starting, it is impossible to take large ignition timing retard to avoid combustion instability and it takes time to activate a catalyst existing downstream of an internal combustion engine. The present invention provides an internal combustion engine control apparatus including an ignition timing control unit to control an ignition timing of an ignition device attached to an internal combustion engine. The internal combustion engine control apparatus includes an in-cylinder temperature raising unit that raises an in-cylinder temperature, the in-cylinder temperature is raised by the in-cylinder temperature raising unit, and a retard amount of the ignition timing of the ignition device is increased by the ignition timing control unit.

A control device for a compression-ignition engine is provided, in which partial compression-ignition combustion including spark ignition (SI) combustion performed by combusting a portion of mixture gas inside a cylinder by spark-ignition followed by compression ignition (CI) combustion performed by causing the rest of the mixture gas inside the cylinder to self-ignite is executed within a part of an operating range of the engine. The device includes a detector configured to detect a parameter related to noise caused by the combustion inside the cylinder, an EGR (exhaust gas recirculation) controller configured to change an EGR ratio being a ratio of exhaust gas introduced into the cylinder, and a combustion controller configured to control the EGR controller to increase the EGR ratio when a noise index value specified based on the detected parameter of the detector is confirmed to exceed a given threshold during the partial compression-ignition combustion.

Methods and systems are provided for diagnosing a laser ignition system of an engine. In one example, a controller may operate the laser in a sealed cylinder hours after key-off. Then, the cylinder may be unsealed and a change in exhaust temperature may be correlated with laser functionality.

A controller for an internal combustion engine includes: a failure determination section which determines a failure state in a case where a relative rotation phase of an intake side valve opening and closing timing control mechanism does not change when controlling the mechanism after starting the driving of a starter motor and trying to change the relative rotation phase of the mechanism in a start control for starting an internal combustion engine. When the section determines a failure, the controller performs at least one of an intake air amount increase control in which an opening degree of a throttle valve is increased, an ignition timing advance angle control in which injection of fuel is performed at a timing earlier than a set timing and ignition is performed, and a multi-injection control in which the fuel is injected immediately before the ignition in addition to the fuel injection in an intake stroke.

A diesel engine system, comprises a selectively actuated cylinder deactivation mechanism configured to lift and lower a valve and to deactivate actuation of the valve. A sleeve comprises a recesses. A controllable latch is movable between a latched condition to catch the latch in the recesses and an unlatched condition configured to collapse the latch from the recesses. A pushrod is coupled to the sleeve, the pushrod is configured to lift and lower the valve when the latch is in the latched condition. The pushrod is further configured to reciprocate inside the sleeve to deactivate actuation of the valve when the latch is in the unlatched condition.

A collapsible valve bridge actuation system that is configured to alter the lift of poppet valves in a reciprocating piston machine cylinder. The system has a rocker arm configured to be actuated by a cam lobe, and a collapsible valve bridge device that is functionally attached to the rocker arm. The device has a deactivation assembly that contains lock pins within a housing and springs. Also, the device is configured to remain rigid, partially collapse, or fully collapse. The extent of collapse is a function of the strength of the springs.