Abstract: A control device for controlling an internal combustion engine equipped with an engine body, a variable compression ratio mechanism A configured to be able to change a mechanical compression ratio of the engine body, and an intake system configured to be able to make exhaust discharged from combustion chambers of the engine body be recirculated to an intake passage of the engine body. The control device is provided with a compression ratio control part controlling the variable compression ratio mechanism A so that the mechanical compression ratio becomes the target compression ratio. The compression ratio control part sets the target compression ratio at a lower value when exhaust is being recirculated at a predetermined operating region at an engine low load side than when exhaust is not being recirculated.

Abstract: 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.

Abstract: An internal combustion engine includes a turbocharger, a variable valve timing mechanism, a variable compression ratio mechanism, and an electronic control unit that controls the variable compression ratio mechanism such that the mechanical compression ratio becomes a target mechanical compression ratio and controls the variable valve timing mechanism such that the valve closing timing of the intake valve becomes a target valve closing timing. The electronic control unit brings the target valve closing timing close to an intake bottom dead center and make the target mechanical compression ratio low, compared to a steady state after the intake pressure reaches a target pressure, in a transient state before the intake pressure reaches the target pressure in a case where the intake pressure is increased to the target pressure higher than an atmospheric pressure by the turbocharger.

Abstract: An in-cylinder pressure sensor is provided. It is determined whether a cylinder for which the in-cylinder air-fuel ratio is to be calculated is a rich cylinder or a lean cylinder. A polytropic index in the expansion stroke is calculated from the in-cylinder pressure detected by the in-cylinder pressure sensor. The calculated polytropic index m is corrected based on an operational condition parameter of an internal combustion engine. An in-cylinder air-fuel ratio is calculated based on the corrected polytropic index m in the expansion stroke, the result of the determination of whether the cylinder is a rich cylinder or a lean cylinder, and an m-A/F curve.

Abstract: An internal combustion engine having a plurality of cylinders comprises a variable compression ratio mechanism A able to change a mechanical compression ratio. The control device comprises a compression ratio detector for detecting a mechanical compression ratio based on a value of the relative position parameter representing a relative positional relationship between the cylinder block 2 and a piston 4, and a compression ratio controller for feedback controlling the mechanical compression ratio so that the mechanical compression ratio becomes a target mechanical compression ratio. In feedback controlling the variable compression ratio mechanism, the compression ratio controller does not use the mechanical compression ratio detected by the compression ratio detector when a crank angle is in a predetermined crank angle range including a time period where the cylinder pressure is equal to or greater than a preset predetermined pressure at least at one cylinder among the plurality of cylinders.

Abstract: A control system comprising a variable valve timing mechanism (B) able to set a closing timing of an intake valve (7), a fuel injector (13) for feeding fuel to a combustion chamber (5), an intake air amount detector (17) for detecting an amount of intake air fed to an intake passage from the outside air, and a pressure sensor (16) for detecting the pressure in the intake passage downstream of a throttle valve (16). When air in the combustion chamber (5) is blown back to the intake passage when injection of fuel is restarted after the fuel injection is stopped at the time of deceleration operation, the basis for calculation of the fuel injection amount in the initial cycle when fuel injection is restarted is switched from the amount of intake air detected by the intake air amount detector (17) to the pressure in the intake passage detected by the pressure sensor (18).

Abstract: A control system for an internal combustion engine is provided with a crankshaft, an intake camshaft with an intake cam, a timing chain, an intake variable valve timing mechanism configured to be able to change at least one of an opening timing and closing timing of an intake valve by controlling a phase of the intake cam, and an electronic control unit configured to set in advance a periodic correction coefficient to vibrate by a period identical to a rotational period of the timing chain and to control the intake variable valve timing mechanism by the periodic correction coefficient to make the phase of the intake cam a target phase.

Abstract: An internal combustion engine includes a turbocharger, a variable valve timing mechanism, a variable compression ratio mechanism, and an electronic control unit that controls the variable compression ratio mechanism such that the mechanical compression ratio becomes a target mechanical compression ratio and controls the variable valve timing mechanism such that the valve closing timing of the intake valve becomes a target valve closing timing. The electronic control unit brings the target valve closing timing close to an intake bottom dead center and make the target mechanical compression ratio low, compared to a steady state after the intake pressure reaches a target pressure, in a transient state before the intake pressure reaches the target pressure in a case where the intake pressure is increased to the target pressure higher than an atmospheric pressure by the turbocharger.

Abstract: A control device for controlling an internal combustion engine equipped with an engine body, a variable compression ratio mechanism A configured to be able to change a mechanical compression ratio of the engine body, and an intake system configured to be able to make exhaust discharged from combustion chambers of the engine body be recirculated to an intake passage of the engine body. The control device is provided with a compression ratio control part controlling the variable compression ratio mechanism A so that the mechanical compression ratio becomes the target compression ratio. The compression ratio control part sets the target compression ratio at a lower value when exhaust is being recirculated at a predetermined operating region at an engine low load side than when exhaust is not being recirculated.

Abstract: An internal combustion engine having a plurality of cylinders comprises a variable compression ratio mechanism A able to change a mechanical compression ratio. The control device comprises a compression ratio detector for detecting a mechanical compression ratio based on a value of the relative position parameter representing a relative positional relationship between the cylinder block 2 and a piston 4, and a compression ratio controller for feedback controlling the mechanical compression ratio so that the mechanical compression ratio becomes a target mechanical compression ratio. In feedback controlling the variable compression ratio mechanism, the compression ratio controller does not use the mechanical compression ratio detected by the compression ratio detector when a crank angle is in a predetermined crank angle range including a time period where the cylinder pressure is equal to or greater than a preset predetermined pressure at least at one cylinder among the plurality of cylinders.

Abstract: A diagnostic system for an internal combustion engine includes an in-cylinder pressure sensor and an ECU. The ECU is configured to: (a) determine whether each cylinder of the evaluation target cylinder group is a lean cylinder; (b) estimate a degree of leanness of the air-fuel ratio of the present lean cylinders when the lean cylinders are present in the evaluation target cylinder group; (c) calculate a polytropic index in an expansion stroke for each cylinder; (d) correlate relationship information for defining a relationship between the polytropic index in the expansion stroke and an air-fuel ratio index value with the polytropic index in the expansion stroke of a reference lean cylinder; and (e) calculate the difference in air-fuel ratio between cylinders on the basis of the polytropic index of the reference lean cylinder, the relationship information correlated with the polytropic index of the reference lean cylinder.

Abstract: A control system for an internal combustion engine is provided with a crankshaft, an intake camshaft with an intake cam, a timing chain, an intake variable valve timing mechanism configured to be able to change at least one of an opening timing and closing timing of an intake valve by controlling a phase of the intake cam, and an electronic control unit configured to set in advance a periodic correction coefficient to vibrate by a period identical to a rotational period of the timing chain and to control the intake variable valve timing mechanism by the periodic correction coefficient to make the phase of the intake cam a target phase.

Abstract: A control system comprising a variable valve timing mechanism (B) able to set a closing timing of an intake valve (7), a fuel injector (13) for feeding fuel to a combustion chamber (5), an intake air amount detector (17) for detecting an amount of intake air fed to an intake passage from the outside air, and a pressure sensor (16) for detecting the pressure in the intake passage downstream of a throttle valve (16). When air in the combustion chamber (5) is blown back to the intake passage when injection of fuel is restarted after the fuel injection is stopped at the time of deceleration operation, the basis for calculation of the fuel injection amount in the initial cycle when fuel injection is restarted is switched from the amount of intake air detected by the intake air amount detector (17) to the pressure in the intake passage detected by the pressure sensor (18).

Abstract: A control system according to one aspect of the present invention is applied to an engine. The engine comprises a port injector and an intake valve driving device capable of changing the closing timing of the intake valve. The engine, if an execution condition for performing a fuel cut control is satisfied when performing an Atkinson cycle, executes the fuel cut control after advancing the closing timing of the intake valve. As a result, by reducing the amount of the fuel which is blown back to the inside of the intake passage in a period where the intake valve is open after intake bottom dead center, the amount of the fuel which flows into the exhaust passage as unburned gas when the fuel cut control is executed can be reduced.

Abstract: A control system according to one aspect of the present invention is applied to an engine. The engine comprises a cylinder injector and an intake valve driving device capable of changing the closing timing of an intake valve. If the execution condition is satisfied when the injection timing of fuel of the cylinder injector is before intake bottom dead center and an Atkinson cycle is carried out, the engine delays the injection timing of the fuel of the cylinder injector to a time after intake bottom dead center, injects the fuel, then executes fuel cut control.

Abstract: An in-cylinder pressure sensor is provided. It is determined whether a cylinder for which the in-cylinder air-fuel ratio is to be calculated is a rich cylinder or a lean cylinder. A polytropic index in the expansion stroke is calculated from the in-cylinder pressure detected by the in-cylinder pressure sensor. The calculated polytropic index m is corrected based on an operational condition parameter of an internal combustion engine. An in-cylinder air-fuel ratio is calculated based on the corrected polytropic index m in the expansion stroke, the result of the determination of whether the cylinder is a rich cylinder or a lean cylinder, and an m-A/F curve.

Abstract: In the present spark ignition internal combustion engine, a shortest self-ignition delay time ?min for a maximum cylinder internal pressure Pmax and a maximum cylinder internal temperature Tmax when equivolume combustion is realized is calculated by using a calculation formula which uses a cylinder internal pressure and a cylinder internal temperature to calculate an self-ignition delay time, and a knock limit ignition timing ITA is determined based on the calculated shortest self-ignition delay time.

Abstract: A diagnostic system for an internal combustion engine includes an in-cylinder pressure sensor and an ECU. The ECU is configured to: (a) determine whether each cylinder of the evaluation target cylinder group is a lean cylinder; (b) estimate a degree of leanness of the air-fuel ratio of the present lean cylinders when the lean cylinders are present in the evaluation target cylinder group; (c) calculate a polytropic index in an expansion stroke for each cylinder; (d) correlate relationship information for defining a relationship between the polytropic index in the expansion stroke and an air-fuel ratio index value with the polytropic index in the expansion stroke of a reference lean cylinder; and (e) calculate the difference in air-fuel ratio between cylinders on the basis of the polytropic index of the reference lean cylinder, the relationship information correlated with the polytropic index of the reference lean cylinder.

Abstract: A base in-cylinder volume is corrected by a learned value to calculate a corrected in-cylinder volume. A difference of a crank angle which gives the corrected in-cylinder volume and the base crank angle is calculated as a “crank angle correction value”, and a base ignition timing is corrected by the crank angle correction value and feedback correction value. An in-cylinder volume at a crank angle where a combustion ratio became a set ratio at the previous combustion is calculated as a “previous in-cylinder volume VFp”, a difference ?VFp of the previous in-cylinder volume VFp with respect to the base in-cylinder volume VBp at the previous combustion is calculated, and the learned value ?VL is updated based on the in-cylinder volume difference VFp.

Abstract: A control apparatus for an internal combustion engine of the present invention switches a steady-state characteristic that defines a relation between an engine load factor and a throttle opening degree between a high atmospheric pressure steady-state characteristic and a low atmospheric pressure steady-state characteristic in accordance with whether or not the atmospheric pressure is higher than a predetermined value. According to the low atmospheric pressure steady-state characteristic, a throttle opening degree corresponding to an identical engine load factor is set to a smaller value compared to the high atmospheric pressure steady-state characteristic in a medium load region, and the throttle opening degree is set so as to increase as the engine load factor increases towards a full load in a region on the side of a higher load factor than the medium load region.