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 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 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.

An engine-knock controlling system for a carburetor-based engine includes one or more cylinders in which combustion occurs, wherein the system also includes a plurality of knock sensors coupled to an engine block, a first wiring harness, a first control unit, a second wiring harness, and a second control unit or an intermediate control unit, or a second control unit and intermediate control unit. The knock sensor(s) detects threatening engine-knock noise as an audible signal and transmits a signal through the wiring harnesses and control units to generate an ignition retarding action to correct the engine misfire and eliminate the knock/ping. Once the engine knock event is resolved, the processor of the first control unit transmits via the second wiring harness a signal to the second control unit or to the intermediate control unit, or to the second control unit and the intermediate control unit, to allow full-advance of ignition timing.

A control system and a control method for an internal combustion engine, which are capable of accurately calculating an in-cylinder gas amount and an EGR ratio by a relatively simple method even in a case where an in-cylinder gas temperature is changed by execution of internal EGR, and properly controlling the engine using the EGR ratio thus calculated. An in-cylinder gas amount Gact actually filled in the cylinder is calculated by correcting an ideal in-cylinder gas amount Gth, which is an amount of gases filled in a cylinder in an ideal state in which it is assumed that no exhaust gases of the engine are recirculated into the cylinder, using an ideal in-cylinder gas temperature Tcylth according to an in-cylinder gas temperature Tcyl, and an EGR ratio REGRT is calculated using the in-cylinder gas amount Gact and an intake air amount Gaircyl.

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.

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.

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.

The present invention provides for predicting peak cylinder temperatures above which knock in an engine may become more frequent and then provides one or more actuation approaches to reduce the knock of the engine while maintaining engine performance. The actuation approaches of the present invention include one or more of direct injection, engine gas recirculation, and spark retarding, where the application of one or more the actuation approaches is determined based upon using operational and engine characteristic inputs as well as modeling and estimation values as inputs in a feedforward control methodology.