Abstract: An ionization current detector for an internal combustion engine which includes a single ionization current detecting circuit 11 connected to a plurality of ignition coils 1 for detecting an ionization current flowing through at least one of the ignition coils 1 upon combustion of the fuel. Accordingly, an ionization current detector which is simple in organization and inexpensive can be obtained.

Abstract: A combustion detect device for use in an internal combustion engine including an ignition coil in which a high voltage for ignition is generated at a secondary winding when the current of a primary winding is cut off, and an ignition plug for discharging and igniting a mixture gas when said high voltage for ignition is applied thereto, the combustion detect device comprises an ion current detection device for detecting an ion current generated due to combustion of a mixture gas by applying a voltage to an ignition plug and a restriction device for restricting a voltage generated in the secondary winding when a primary winding is turned on to conduct.

Abstract: In an ion current detecting device for an internal combustion engine, an ion current detecting circuit for detecting an ion current produced when the gas mixture is burnt by spark discharges between the electrodes of a spark plug operates to mask the detection signal of the ion current for predetermined periods of time in the intervals in which noise pulses are produced in association with excitation and unexcitation of ignition coil. Hence, the noise pulses are eliminated from the detection signal, whereby it can be positively determined from the presence or absence of the detection signal whether or not the gas mixture has been burnt.

Abstract: Misfiring in a cylinder of an engine can be detected with high reliability using a statistical treatment even if the level of ion current generated by a spark plug upon ignition thereof is affected by noise. An ion current, which is generated when a spark plug for a cylinder discharges, is detected to provide a corresponding voltage which is then integrated or peak held to produce a current component signal which is generated for a predetermined time from the time of discharge of the spark plug. The current component signal is used as misfiring information and compared with a prescribed threshold so as to determine whether there is misfiring in the cylinder. Misfirings thus detected are counted so as to evaluate the state or extent of misfiring in the cylinder. If the state of misfiring is serious, the fuel supply to the cylinder is stopped.

Abstract: An engine control apparatus can significantly improve reliability in misfire detection by preventing erroneous detection of the level of an ion current due to noise superposition. An angular position detector generates a reference position signal representative of a predetermined crank angle of each engine cylinder in synchronism with the rotation of an internal combustion engine. Sensors detect an operating state of the engine. An ion current detector detects an ion current in at least one of the engine cylinders. An engine control parameter setter sets a control parameter for the engine in accordance with the reference position signal and the engine operating state. A misfire detector generates a misfire detection signal indicative of occurrence of misfiring in the at least one engine cylinder on the basis of a value of the ion current. The control parameter setter corrects the control parameter on the basis of the misfire detection signal.

Abstract: An engine control apparatus capable of detecting occurrence of abnormality in the ignition coil with high reliability. The apparatus includes an initial detection level hold device for holding an initial level (In) of a detected ion current value I, and an ignition coil diagnosis device for generating an abnormality decision signal of the ignition coil in dependence on the initial level of the ion current. By positively utilizing noise produced in an initial phase of the ignition cycle instead of eliminating it, the abnormality decision signal is generated, on the basis of which an appropriate engine protection measure is taken.

Abstract: A direct current power supply applies a positive voltage between the center electrode and the ground electrode of a spark plug in an internal combustion engine after discharge of the spark plug. Ionic current flowing between the electrodes due to the positive voltage is measured by a current sensor. The ionic current caused by the positive voltage is due to electrons, so it has a large magnitude and can be easily measured.

Abstract: An ignition system for internal combustion engines has an ignition coil having a primary winding and a secondary winding. The secondary winding supplies a high voltage for ignition to an ignition plug when the ignition coil is energized at the primary winding at a predetermined period. A voltage producing circuit produces a voltage on the basis of a signal developed across the primary winding when the primary winding is energized at a predetermined period. The voltage causes discharge across the electrodes of the ignition plug to form a path for an ion current developed in the cylinder. A comparator or detector detects the ion current to determine the combustion in a cylinder.

Abstract: A capacitor is connected to an ignition coil for an internal combustion engine so as to be charged by ignition current generated by the ignition coil. After firing of a spark plug in a cylinder by the ignition current, the voltage across the capacitor is applied between the center electrode and the ground electrode of the spark plug to induce an ionic current between the electrodes. The resulting ionic current is measured by a current sensor connected to the capacitor.

Abstract: A knocking device for an internal combustion engine which detects the ionization current through an ignition coil just prior to the time of ignition, and judges whether or not the ionization current is above a predetermined level after a predetermined time or crank angle from the ignition. If the ionization current is above the predetermined level, it is judged that knocking has taken place. Accordingly, knocking can be detected simply and surely.

Abstract: A combustion detecting apparatus for an internal combustion engine capable of discriminatively detecting the state of combustion, normal combustion or abnormal combustion such as misfiring, from each other. By applying a voltage of positive polarity to a spark plug for each engine cylinder, an ion current of negative polarity, which is generated upon combustion of a mixture in the cylinder, is detected. Subsequently, the detected ion current signal of negative polarity is transformed to a signal of positive polarity which is then subjected to waveform shaping by using comparators to obtain an ion current detection output signal which is utilized in making decision as to occurrence of misfiring. By making use of the ion current of negative polarity, a high signal level is realized to detect the state of combustion with high reliability even in a high speed or under a heavy load of the engine.

Abstract: An apparatus for detecting combustion in an internal combustion engine which comprises: a plurality of cylinders wherein an ignition control is performed being synchronized with a revolution number of the internal combustion engine; and an ionic current detector installed at an ignition plug of at least one cylinder of the plurality of cylinders; the ionic current detector including a device for generating a voltage which corresponds to a level of an ionic current generated by the ignition plug, a device for generating a threshold value which is a combustion determining standard, and a comparator which generates an output signal that shows a combustion state, by comparing the voltage with the threshold value; the device for generating a threshold value is composed of a threshold level variable circuit which generates a threshold value corresponding to a running condition of the engine.

Abstract: Method and apparatus for detecting a failure of a pressure sensor provided in association with a cylinder of an internal combustion engine for detecting the pressure therein. Decision as to occurrence of a failure in the pressure sensor is made on the basis of the cylinder pressure detected by the pressure sensor through comparison with a prescribed reference value or range. Failure of the pressure sensor is determined if the detected cylinder pressure deviates from the reference value or range by a predetermined amount. Upon detection of a pressure sensor failure, an engine control parameter such as ignition timing for controlling the associated cylinder in dependence on the pressure sensor output is set to a fixed value or the operation of the cylinder is stopped.

Abstract: An apparatus for detecting combustion in an internal combustion engine which comprises: a plurality of cylinders wherein an ignition control is performed being synchronized with a revolution number of the internal combustion engine; and an ionic current detector installed at an ignition plug of at least one cylinder of the plurality of cylinders; said ionic currrent detector including means for generating a voltage which corresponds to a level of an ionic current generated by the ignition plug, means for generating a threshold value which is a combustion determining standard, and a comparator which generates an output signal that shows a combustion state, by comparing the voltage with the threshold value; said means for generating a threshold value is composed of a threshold level variable circuit which generates a threshold value corresponding to a running condition of the engine.

Abstract: A control device for a multi-cylinder engine comprises, in addition to a sensor 11 for detecting reference rotational positions of the crank shaft 1, an ionization current detector 41 for detecting the ionization current across a spark plug 33 of a cylinder. From the output of the sensor 11, the microcomputer 40 discriminates the group of cylinders which are in the compression and the exhaust stroke. For a short period after the start of the engine, the group of cylinders in the compression and the exhaust stroke are ignited simultaneously. During this short period, the cylinder in the compression stroke is discriminated from the group of cylinders in the compression and the exhaust stroke, on the basis of the output of the ionization current detector 41, and the number of succesive discriminations of the cylinder in the compression stroke is counted.