Methods and systems are provided for indicating degradation of a VCR mechanism that mechanically alters a cylinder compression ratio. Degradation is detected based on an elevated knock incidence and increased spark retard usage. If the VCR mechanism is stuck, knock and pre-ignition that could be induced by continued operation in a higher than intended compression ratio is mitigated by limiting the engine load.

When it is determined that the igniting environment is out of the desired range, the variable valve mechanism is controlled so that the swirl ratio is increased. When the swirl ratio becomes high, the discharge spark and the initial flame move largely in the flow direction of the swirl flow SW and approach the closest fuel spray. Therefore, the discharge spark and the initial flame are attracted to the closest fuel spray and the initial flame enlarges by involving the closest fuel spray (middle stage of FIG. 7). Further, the initial flame enlarges further by involving surrounded fuel spray (lower stage of FIG. 7).

A control system and method for a vehicle having a powertrain comprising a torque generating system and an automatic transmission each utilize a pedal position sensor configured to measure a position of an accelerator pedal of the vehicle and a controller configured to, based on the accelerator pedal position, detect a pedal tip-in or tip-out event and, in response to detecting the pedal tip-in or tip-out event: (i) determine a desired output torque for the torque generating system corresponding to the pedal tip-in or tip-out event and (ii) command the torque generating system to gradually transition, over a period, from its current output torque to the desired output torque to mitigate clunk caused by abrupt contact between gear teeth of the torque generating system shaft and the automatic transmission shaft.

An internal combustion engine includes a first intake valve, a second intake valve, an accelerator open degree sensor that detects a load state, and an ECU 26 that controls the valve opening timing of the first and second intake valves and an amount of intake gas introduced to a combustion chamber from the first and second intake valves. When a load of a vehicle increases, the ECU reduces the ratio of the amount of intake gas from, among the two or more intake valves, the second intake valve having a later valve opening timing, whereas when the load decreases, the ECU increases the ratio.

A method for operating an internal combustion engine of a motor vehicle involves directly injecting fuel into a combustion chamber using an injection device, and a mixture of the fuel and air is ignited in the combustion chamber by an ignition device. The internal combustion engine is operated selectively in at least one first operating mode with at least one first valve lift of at least one gas exchange valve of the internal combustion engine, associated with the combustion chamber, or in at least one second operating mode with at least one second valve lift of the gas exchange valve, which is smaller than the first valve lift. For assisting a charge movement of the mixture in the second operating mode, at least one further injection of fuel directly into the combustion chamber is carried out prior to the ignition.

Methods and systems are provided for adjusting combustion parameters to increase combustion stability during conditions when condensate formed in a charge air cooler may enter cylinders of an engine. In response to increased mass air flow and a condensate level in the charge air cooler, the engine may combust a rich air-fuel ratio while increasing a positive valve overlap.

An actuating system of an engine valve comprises a movable member, for example, in the form of a master piston controlled by a cam of a camshaft. A slave piston is hydraulically controlled by the master piston by means of a volume of pressurized fluid, to open said engine valve against the action of a return spring. The system also comprises an auxiliary device for applying an additional force to the engine valve to keep the engine valve in a closed position. The auxiliary device is configured or controlled in such a way that the total force tending to keep the engine valve in its closed position varies during each rotation cycle of the cam. The total force is higher at least in one part of the rotation cycle of the cam wherein the engine valve must remain in its closed position, and is, instead, reduced at least in one part of the rotation cycle of the cam wherein the engine valve is not in its closed position.

A variable valve device can change valve operations of a cylinder head in which a cam chain is disposed at a center in a predetermined direction where cylinders are arranged and spark plugs are arranged by recessing outer walls on both sides in the direction in a concave shape. The device includes, for each cylinder, a rocker shaft extending along the direction, rocker arms supported by the rocker shaft, a connecting pin disposed in a pin hole of one of the rocker arms, a return pin disposed in a pin hole of the other of the rocker arms, a pressing member that causes the connecting pin to push the return pin, and a repulsive member that causes the return pin to push back the connecting pin, and the pins and the members are separated from the plug in a direction orthogonal to the direction in a plan view.

An internal combustion engine may have an intake valve device. A sudden load variation may be carried out in which a torque provided by the internal combustion engine is increased from a first value to a second value which is higher than the first value. While the sudden load variation is being carried out, the intake valve device may be operated according to an operating method different from the second operating method and is thereby closed later than in the second operating method. After the sudden load variation has been carried out, and while the internal combustion engine provides the torque having the second value after the sudden load variation has been carried out, the internal combustion engine may be switched over from the first operating method different from the second operating method to the second operating method.

When a stop request to the engine is issued, it is determined whether or not all of the drive cams are large cams. When it is determined that at least one of the small cams is included in the drive cams, the engine is continued to drive for a while and a switch control for switching the drive cams from the small cams to the large cams is executed within the duration. A self-holding type solenoid is used to switch between the small cams and the large cams. In the switch control, a permission to stop the engine is output at a timing when the pin protrudable section of the final cylinder #2 has elapsed.