An internal combustion engine system includes an engine with a plurality of pistons housed in respective ones of a plurality of cylinders, an air intake system to provide air to the plurality of cylinders through respective ones of a plurality of intake valves, an exhaust system to release exhaust gas from the plurality of cylinders through respective one of a plurality of exhaust valves. The internal combustion engine uses vacuum braking and/or compression release braking in response to one or more braking conditions.

In a valve timing control system, a control command unit includes: a first stage setting block and a next stage setting block. The first stage setting block sets a retard holding command value as a control command value to introduce hydraulic fluid to each retard operation chamber under a state where a rotation phase is locked, to start applying an operation pressure more than or equal to an unlock pressure to a lock component. The next stage setting block sets an advance holding command value as a control command value to introduce hydraulic fluid to each advance operation chamber, after setting the retard holding command value, to maintain the applying of the operation pressure more than or equal to the unlock pressure to the lock component.

A torque requesting module generates a torque request for an engine based on driver input. A model predictive control (MPC) module: identifies sets of possible target values based on the torque request, each of the sets of possible target values including target effective throttle area percentage; determines predicted operating parameters for the sets of possible target values, respectively; determines cost values for the sets of possible target values, respectively; selects one of the sets of possible target values based on the cost values; and sets target values based on the possible target values of the selected one of the sets, respectively, the target values including a target pressure ratio across the throttle valve. A target area module determines a target opening area of the throttle valve based on the target effective throttle area percentage ratio. A throttle actuator module controls the throttle valve based on the target opening.

A catalyst temperature control system of a vehicle includes a fuel control module configured to control fuel injection based on a target air/fuel ratio that is fuel lean relative to a stoichiometric air/fuel ratio and a target fuel injection start timing. An exhaust gas recirculation (EGR) control module is configured to control an EGR valve based on a target EGR opening. An adjustment module is configured to, when a temperature of a catalyst in an exhaust system is less than a sum of a predetermined light-out temperature of the catalyst and a predetermined temperature and the target air/fuel ratio is fuel lean relative to the stoichiometric air/fuel ratio, based on a comparison of an engine speed and a predetermined engine speed, selectively adjust at least one of: a target throttle opening, a target spark timing, the target fuel injection start timing, the target air/fuel ratio, and the target EGR opening.

A control method of valve opening and closing for an engine of which an intake continuous variable valve duration (CVVD) apparatus and an intake continuous variable valve timing (CVVT) apparatus are provided on the intake side, and an exhaust continuous variable valve duration (CVVD) apparatus and an exhaust continuous variable valve timing (CVVT) apparatus are provided on the exhaust side. The control method includes: determining, by a controller, a driving region among a predetermined plurality of driving regions according to a speed and a torque of the engine; and controlling, by the controller, opening timing, closing timing, and opening duration of each of an intake valve and an exhaust valve according to the driving region of the engine. The intake valve closing (IVC) timing is before a bottom dead center (BDC) in all driving regions.

A variable valve system including a crank angle sensor that measures a rotation angle of a crankshaft, a cam angle sensor that measures a rotation angle of a camshaft coupled to the crankshaft and which opens and closes valves, and a controller that controls the internal combustion engine. At least one of the crank angle sensor or the cam angle sensor is configured as an absolute angle sensor that measures an absolute rotation angle and outputs a voltage signal corresponding to this rotation angle. The controller is configured to perform a correction operation that corrects a rotation angle value calculated based on the voltage signal.

A catalyst temperature control system of a vehicle includes a fuel control module configured to control fuel injection based on a target air/fuel ratio that is fuel lean relative to a stoichiometric air/fuel ratio and a target fuel injection start timing. An exhaust gas recirculation (EGR) control module is configured to control an EGR valve based on a target EGR opening. An adjustment module is configured to, when a temperature of a catalyst in an exhaust system is less than a sum of a predetermined light-out temperature of the catalyst and a predetermined temperature and the target air/fuel ratio is fuel lean relative to the stoichiometric air/fuel ratio, based on a comparison of an engine speed and a predetermined engine speed, selectively adjust at least one of: a target throttle opening, a target spark timing, the target fuel injection start timing, the target air/fuel ratio, and the target EGR opening.

Methods and systems are provided for estimating engine oil temperature during conditions when sensors used for engine oil temperature measurement are not functional or not reliable. A null duty cycle of a solenoid spool valve of a variable cam timing mechanism is estimated. Then, a calibrated relationship between the duty cycle, an angular velocity of the associated cam, and the engine oil temperature is used to estimate an engine oil temperature when existing sensors used in the calculation of engine oil temperature calculation become unreliable.

A method of implementing control logic of a compression-ignition engine is provided. A controller outputs a signal to a injector and a variable valve operating mechanism so that a gas-fuel ratio (G/F) becomes leaner than a stoichiometric air fuel ratio, and an air-fuel ratio (A/F) becomes equal to or richer than the stoichiometric air fuel ratio, and to an ignition plug so that unburnt mixture gas combusts by self-ignition after the ignition plug ignites mixture gas inside a combustion chamber. The method includes steps of determining a geometric compression ratio and determining the control logic defining an intake valve close timing IVC. IVC (deg.aBDC) is determined so that the following expression is satisfied: if the geometric compression ratio is 10<17,

0.4234.sub..sup.222.926.sub.+207.84+CIVC0.4234.sub..sup.2+22.926.sub.167.84+C

where C is a correction term according to an engine speed NE (rpm),

C=3.310.sup.10NE.sup.31.010.sup.6NE.sup.2+7.010.sup.4NE.

In a control device and a control method for a variable valve timing mechanism according to the present invention, the rotational phase of a camshaft is measured based on the cam angle signal and crank angle signal upon receiving each pulse of the cam angle signal, and the rotational phase change over time within a period of the cam angle signal is measured based on the motor angle signal. It is decided whether the cam angle signal and/or crank angle signal has a prescribed pulse pattern at a diagnostic timing that comes after the last pulse of the cam angle signal. When this decision result is positive, it is then decided whether the motor angle sensor operates normally or abnormally based on the rotational phase and the amount of rotational phase change that are measured when the last pulse of the cam angle signal is received before the diagnostic timing.