A method or system to determine peak firing pressure of a cylinder of an engine having a crank shaft. The method includes accessing a knock signal received from a knock sensor of the cylinder. The method includes determining a location of peak firing pressure based at least in part on the knock signal. The location of peak firing pressure is associated with combustion of the engine and corresponds to a time or a crank angle of the crankshaft. The method includes generating an indication of the location of peak firing pressure.

A method of controlling an internal combustion engine of a marine propulsion device includes receiving a knock sensor signal over an analysis period in a combustion cycle of an internal combustion engine, and subdividing the analysis period into at least a first knock window and a second knock window. The method further includes determining that the knock sensor signal exceeds a threshold in each of the first knock window and the second knock window, and that the knock sensor signal intensity is greater in the first knock window than in the second knock window. At least one combustion parameter is then adjusted for the internal combustion engine to eliminate knocking.

Methods and systems are provided for determining engine knock sensor degradation. In one example, a method may include sending an excitation signal to an actuator to generate vibrations in the absence of engine combustion, and determining engine knock sensor degradation by comparing the knock sensor output with the excitation signal.

A method of deriving the health of a first cylinder in a reciprocating device includes receiving a first signal from a first knock sensor in proximity to the first cylinder, receiving a second signal from a second knock sensor in proximity to a second cylinder, processing the first signal and the second signal, and deriving the health of the first cylinder by determining whether the first signal is coherent with the second signal.

A method of diagnosing a knock sensor includes steps of receiving data from the knock sensor, the knock sensor configured to be coupled to an engine, processing the data to derive one or more events from the data, and determining whether the one or more events took place at a known time or a known crank position.

The present invention provides an ignition timing control device and ignition timing control system for an internal combustion engine, capable of controlling an ignition timing of the engine promptly in response to a change in engine operating conditions. An ignition timing adjustment unit (43) is adapted to correct the ignition timing to a proper ignition timing in a retard region with reference to a maximum advance value based on a knocking signal outputted from a knocking detection unit (41) and a reference ignition signal (A) outputted from an external electronic control unit (37). The output signal from the ignition timing adjustment unit (43) can be thus promptly adjusted by retarding the ignition timing relative to a reference ignition timing given from the external electronic control unit (37) upon detection of engine knocking.

A method is disclosed for detecting an auto-ignition in a spark-ignited internal combustion engine having at least one cylinder, wherein values for the combustion chamber pressure are measured during a compression stroke of the internal combustion engine at defined crankshaft angles within an evaluation window, a filtered pressure value is determined from the measured values for the combustion chamber pressure, theoretical pressure values in the combustion chamber that would arise if no combustion took place in the combustion chamber are determined for the defined crankshaft angles, the value of the pressure difference between the filtered pressure value and the theoretical pressure values is calculated, the value of the pressure difference is compared with a specified threshold value, and, if the threshold value is exceeded, an auto-ignition in the combustion chamber is inferred.

In order to solve a problem that in an internal combustion engine in which abnormal combustion (knocking or an accidental fire) of an engine is detected from an ion signal, the setting of an abnormal combustion determination threshold value under a transient condition in which an engine operating state abruptly changes is difficult to thereby cause erroneous determination, the present invention is an engine control device provided with an ion signal detection means for detecting ions generated during combustion, and provided with an abnormal combustion determination means for determining knocking or an accidental fire according to an ion signal detected by the detection means, the engine control device being characterized by being provided with an in-cylinder temperature estimation means for estimating the in-cylinder temperature in a normal combustion cycle under a current operating condition of the engine, and by setting the knocking determination threshold value or accidental fire determination threshold value of the ion signal on the basis of the estimated in-cylinder temperature information. Consequently, it becomes possible to accurately detect abnormal combustion even under a transient operating condition.

There is provided a pressure detection device including: a pressure detection element which receives pressure so as to output a detection signal corresponding to the pressure P; and a processing circuit which processes and outputs the detection signal output from the pressure detection element, where the processing circuit includes: a voltage transformation circuit which only transforms a power supply voltage fed from an external power supply so as to obtain a first reference voltage with a predetermined voltage value; an integrator circuit which uses the first reference voltage as an operation reference to perform integral processing on the detection signal so as to convert the detection signal into a voltage waveform; and at least one or more amplifier circuits which use a second reference voltage with a predetermined voltage value as an operation reference to perform amplification processing on an output signal from the integrator circuit.

There is provided a pressure detection device (10) including: a pressure detection element (21) which receives pressure (P) so as to output a detection signal (Qi) corresponding to the pressure (P); and a processing circuit (30) which processes and outputs the detection signal (Qi) output from the pressure detection element (21), where on a circuit board (40) on which a conductor pattern is formed, an integrated circuit (IC1) including an analog circuit which uses a reference voltage (Vr) set to a predetermined voltage value as an operation reference and converts the detection signal (Qi) into a voltage waveform is mounted, and the processing circuit (30) includes an input circuit 50 which feeds the detection signal (Qi) to the integrated circuit (IC1) and a shield pattern (SHP1) which surrounds the region of at least a part of the input circuit (50) and to which the reference voltage (Vr) is applied.