A process to adjust the ignition timing of an air-fuel mixture in a combustion chamber of an internal combustion engine, the process comprises determining a first quantity indicative of a pressure of the mixture for a cycle of the engine, determining a second quantity indicative of a speed of the engine, determining a third quantity indicative of a first temperature of a conditioning fluid, providing a heat exchange mathematical model for the combustion chamber, which maps the three quantities from the first to the third one onto a fourth quantity indicative of a second temperature of a wall portion around the combustion chamber, estimating the fourth quantity by means of the three determined quantities and by means of the mathematical model, and adjusting the ignition timing as a function of the fourth estimated quantity.

A control device of the present invention is applied to an engine provided with a fuel injection valve which directly injects fuel into a combustion chamber. The control device includes a pre-ignition prediction unit which predicts occurrence of pre-ignition when the engine is started; and an injection control unit which causes fuel to be injected in an expansion stroke from the fuel injection valve when occurrence of pre-ignition is predicted by the pre-ignition prediction unit. Thus, it is possible to prevent pre-ignition without lowering the effective compression ratio.

A control apparatus for an internal combustion engine is provided to calculate, on the basis of the output values of the in-cylinder pressure sensor, a combustion index value which indicates the stability of combustion. If reduction of knock is required, the spark timing is retarded. An increment of injected fuel is executed in such a manner that a combustion index value that indicates the actual stability of combustion at a retard execution cycle that is a combustion cycle at which the retard of the spark timing is executed approaches a target value of a combustion index value that indicates the stability of combustion at a before-retard cycle.

A control device includes an electronic control unit. The electronic control unit is configured to calculate an ignitionability index value and a combustion timing index value. The electronic control unit is configured to store relevant information defining a relationship between the ignitionability index value and the combustion timing index value, and a torque fluctuation limit value. The electronic control unit is configured to calculate a distance between a current operating point, which is specified by the ignitionability index value and the combustion timing index value, and a point on the torque fluctuation limit line. The electronic control unit is configured to retard ignition timing when the distance is larger than a threshold value, and enrich an air-fuel ratio and retard the ignition timing when the distance is equal to or smaller than the threshold value.

A method for controlling an internal combustion engine is disclosed. The method may include receiving knock data corresponding to knock levels over a time period. The method may also include determining from the knock data whether the knock levels change over the time period. Further, the method may include determining that a variation in the gas composition of the gaseous fuel supplied to the internal combustion engine has occurred when the knock levels change over the time period. In addition, the method may include adjusting an operating condition of the internal combustion engine to adapt a knock susceptibility of the internal combustion engine to the varying gas composition.

Operating a gaseous fuel engine system includes determining a detonation level in combustion cylinders in an engine in the gaseous fuel engine system, comparing the detonation level to a detonation level limit, calculating a detonation error, and limiting an engine load of the engine to a derated engine load level based on a reduction to intake manifold air pressure (IMAP) that is performed responsive to the detonation error. The gaseous fuel engine system can be operated at a reduced, derated engine load, rather than being shut down, and permitted to increase in engine load level as detonation events clear. Related control logic and structure are disclosed.

Systems and methods for operating an engine with deactivating and non-deactivating valves are presented. In one example, estimates of engine fuel consumption for operating the engine with a plurality of cylinder modes or patterns while a transmission is engaged in different gears are determined and are used as a basis for deactivating engine cylinders.

A knock determination apparatus for an internal combustion engine calculates a knock intensity based on an output signal of an in-cylinder pressure sensor in a gate range for knock determination. When the calculated knock intensity is larger than a knock determination threshold value, the knock determination apparatus determines that knock has occurred. Further, the knock determination apparatus calculates an integrated intensity which is an integrated value of knock intensities that are equal to or larger than a knock intensity at a point of 97% or more in a target knock level among knock intensities that are calculated at the respective cycles during continuous N cycles in the same cylinder. Furthermore, the knock determination apparatus corrects a knock determination threshold value so that the difference between the calculated integrated intensity and a target integrated intensity becomes small.

Methods and systems are provided for synergizing the benefits of a variable compression ratio engine in a hybrid vehicle system. A vehicle controller may hold the engine in a lower compression ratio during engine pull-ups and pull-downs, in particular when passing through a low speed region where compression bobbles can occur. During engine operation, in response to a change in driver demand, the controller may opt to switch the compression ratio or maintain a current compression ratio while smoothing a torque deficit using motor torque, the selection based on fuel economy.

A method for detecting glow ignition of a fuel-air mixture in a combustion chamber of an internal combustion engine having at least one first cylinder and at least one second cylinder, the at least one first and second cylinders being connected by a crankshaft, according to which method partial segment times of the at least one first cylinder are measured. The method is characterized in that partial segment times of the at least one second cylinder are measured and a reference characteristic for the glow ignition is formed by a comparison of partial segment times of the at least one first cylinder with partial segment times of the at least one second cylinder and subsequently a signal is generated for the detection of the glow ignition on the basis of the comparison.