Abstract: In a multi-cylinder internal combustion engine including a plurality of fuel injection valves corresponding to a plurality of cylinders, respectively, and a catalytic converter provided in an exhaust system common to the cylinders, the concentration of oxygen in the exhaust gas from the engine is precisely controlled in accordance with the operational condition of the engine in a low-temperature state of the engine for the prompt activation of the catalyst. When the engine is at a low temperature, the operation of the fuel injection valves is controlled so as to stop the supplying of a fuel into the particular cylinders and, the operation of a valve operating characteristic changing means is controlled to adjust the amounts of air drawn and discharged on the basis of conditions detected by operational condition detecting means and at such low temperature to thereby control the oxygen supplied to the catalyst in the catalytic converter whereby the activity of the catalyst can be controlled.

Abstract: An internal combustion engine has an adsorber arranged in the exhaust passage for adsorbing unburnt components in exhaust gases, and an exhaust gas-purifying device arranged in the exhaust passage at a location downstream of the adsorber. The exhaust gas-purifying device is equipped with a heater. An ignition timing of an internal combustion engine is retarded when the engine is started at a low engine temperature. The retardation of the ignition timing is restrained over a time period from the start of the engine to a time point the exhaust gas-purifying device is warmed up to a predetermined activated condition.

Abstract: In an engine exhaust emission control system, a ternary catalyst and a hydrocarbon adsorber are provided in an exhaust passageway from an engine. The ternary catalyst includes first passages through which an exhaust gas discharged from the engine flows, and second passages through which the exhaust gas which has flowed through the first passages and the hydrocarbon adsorber flows. The first and second passages are laminated to each other to enable heat exchange therebetween. The hydrocarbon adsorber is capable of being cooled by a cooling medium. Thus, it is possible to reliably prevent hydrocarbons in the exhaust gas from being released to the atmosphere during the cold start of the engine.

Abstract: A combustion state-detecting system for internal combustion engines has a crank angle sensor which generates a crank angle signal with a predetermined period shorter than a firing period of the engine whenever the crankshaft rotates through a predetermined angle. A value of the rotational speed of the engine is detected whenever the crank angle signal is generated. A first average value of the detected engine rotational speed is calculated over every period of one rotation of the crankshaft, followed by calculating a second average value of the first average value over every firing period, to thereby calculate a rate of variation in the second average value over every firing period. Values of the rate of variation are averaged over a predetermined number of ignition cycles of the engine, to obtain a third average value. A cumulative value of the absolute value of a difference between the third average value and the rate of variation is calculated over the above predetermined number of ignition cycles.

Abstract: An exhaust gas-purging system for an internal combustion engine includes a catalyst arranged in an exhaust passage of the engine, for purifying exhaust gases emitted from the engine. The system detects an engine operating condition and a catalyst temperature parameter indicative of the temperature of the catalyst. The supply of secondary air to the exhaust passage and the flow path cross-sectional area of the exhaust passage are controlled based on at least one of the operating condition of the engine and the catalyst temperature parameter.

Abstract: A misfire-detecting system for an internal combustion engine detects occurrence of a misfire in the engine, based on voltage between both ends of a spark plug assumed when sparking discharge takes place at the spark plug. A diode is arranged in an ignition secondary circuit of the engine, for checking reverse current flowing in the circuit in a direction reverse to the direction of flow of current occurring when spark ignition takes place at the spark plug. An ECU detects reverse current flowing in the ignition secondary circuit, and detects an abnormality of the diode, based on the detected reverse current.

Abstract: A spark plug cap covering the terminal of a spark plug for an internal combustion engine, made up of an insulative cap body, an ignition coil unit case housing the coil and having a terminal for the ignition coil, a first conductive shaft housed in the insulative cap body for carrying an ignition voltage produced by the ignition coil to the spark plug terminal, and a second conductor located around the first conductor keeping a predetermined distance therefrom separated by the insulative material of the cap body such that a capacitor is formed between the first and second conductors for detecting the ignition voltage.

Abstract: A combustion state-determining system for an internal combustion engine, in which an ECU detects misfires occurring in the engine. A first counter counts the number of times of occurrence of misfires detected every predetermined number of firing cycles, and a second counter counts the number of times of occurrence of misfires detected every predetermined repetition period which is a predetermined integer times as long as the predetermined number of firing cycles. The count value of the first counter is compared with a first reference value and a second reference value smaller than the first reference value every predetermined number of firing cycles, to determine that the engine is in a combustion state adversely affecting at least one exhaust system component part when the former is larger than the latter.

Abstract: An exhaust gas-purifying system for an internal combustion engine is provided with hydrocarbon-adsorbing catalyzer for adsorbing unburnt gas components present in exhaust gases. At least one exhaust gas-purifying catalyzer is arranged in the exhaust passage at a location downstream of the hydrocarbon-adsorbing catalyzer. A bypass passage bypasses the hydrocarbon-purifying catalyzer. A changeover valve is arranged in the exhaust passage at a branchpoint between the bypass passage and the exhaust passage, for selecting a first flow path in which exhaust gases are guided to the unburnt gas component-adsorbing catalyzer, or a second flow path in which exhaust gases are guided through the bypass passage. First and second exhaust gas concentration sensors are arranged in the exhaust passage at locations upstream and downstream of the hydrocarbon-purifying catalyzer.

Abstract: An ignition coil has a capacitor for detecting ignition voltage of a spark-ignition internal combustion engine to determine if misfire occurs. The ignition coil has a primary winding and a secondary winding both wound around a core. A connector section, connected to the secondary winding by a lead, is provided for receiving a high-voltage cable to transmit the secondary winding voltage current to an ignition distributor. These components are embedded integrally in an insulator resin at the time of completing the coil. A conductor is also embedded in the insulator resin such that it is located around the connector section keeping a predetermined distance therefrom and sandwiching the insulator resin, whereby a capacitor, which constitutes a capacitive divider in cooperation with a second capacitor for detecting misfire through the ignition voltage, is formed between the connector section and the conductor. A ceramic insulator can be positioned between the conductor and the connector section.

Abstract: A connector disposed at a distal end of a high tension cord having a conductive core therein for carrying an ignition voltage current for igniting air-fuel mixture in an internal combustion engine. A conductive connecting member is connected to the conductive core and a cover made of an insulation material is disposed therearound. A conductor is embedded in the insulation cover such that it locates around the conductive connecting member keeping a predetermined distance therefrom and sandwiching a portion of the insulation cover, whereby a capacitor, which constitutes a capacitive divider in cooperation with a second capacitor for detecting misfire through the ignition voltage, is formed between the conductive connecting member and the conductor. A ceramic insulator can be positioned between the conductor and the conductive connecting member section. The conductor can further be electrically shielded.

Abstract: A sparking voltage detecting device for an internal combustion engine having an ignition system having at least one secondary side high-tension cord, is mounted on the secondary side high-tension cord, for detecting sparking voltage generated in the engine. A main body formed of an insulating material has at least one through hole formed therein. The main body includes a pair of halves fabricated separately at least in part from each other and abutting each other along a line extending through the center of the main body. The high-tension cord is fitted through the through hole in a liquidtight manner. At least one conductive member is embedded in the main body at a location radially outward of the through hole and spaced from the high-tension cord by a predetermined distance.

Abstract: An ignition coil unit for an internal combustion engine for containing an ignition voltage detective capacitor for misfire discrimination, including a core, a primary and a secondary coil wound around the core, and a case housing the core and the primary and secondary coils which is filled with an insulative material. In this unit, a first conductive electrode plate is placed in the case and electrically connected with the output of the secondary coil, and a second conductive electrode plate is also placed in the case in parallel with the first conductive electrode plate while maintaining a predetermined distance therefrom. An insulator is interposed between the first and second conductive electrode plates forming a capacitor that uses the insulator as the dielectric.

Abstract: A device according to an aspect of the invention detects abnormality of spark plugs of an internal combustion engine. A value related to electric resistance across a gap between electrodes of each spark plug is measured. Next, it is determined whether or not the measured value, related to the electric resistance, assumes a value indicating that the electric resistance is below a predetermined value, when the engine is determined to be in a non-combustive state. The spark plug is determined to be abnormal when it is determined that the measured value, related to the electric resistance, assumes the value indicating that the electric resistance is below the predetermined value. A misfire-detecting system according to another aspect of the invention incorporates the above device.

Abstract: A combustion state-detecting system, for internal combustion engines, has a crank angle sensor. The crank angle sensor generates a crank angle signal with a predetermined period shorter than a firing period of the engine whenever the crankshaft rotates through a predetermined angle. A value of the rotational speed of the engine is detected whenever the crank angle signal is generated. A first average value of the detected engine rotational speed is calculated over a period of one rotation of the crankshaft, followed by calculating a second average value of the first average value over every firing period, to thereby calculate a rate of variation in the second average value over every firing period. The rate of variation is compared with a predetermined value, to determine whether or not the engine is in a degraded state of combustion.

Abstract: A misfire-determining system for an internal combustion engine detects sparking voltage generated when ignition is sequentially performed for each of cylinders. Adjacent durations of sparking voltage detected for respective cylinders are separately compared with a predetermined reference value by respective different misfire-determining circuits to determine whether or not a misfire has occurred.

Abstract: A method of manufacturing a spark plug cap covering a spark plug for an internal combustion engine, equipped with an ignition voltage detective capacitor having a first conductor housed in a cap body for carrying an ignition voltage produced by an ignition coil to the spark plug and a second conductor located keeping a predetermined distance from the first conductor while sandwiching an insulative material such that the capacitor is formed between the first and second conductors for detecting the ignition voltage. The method comprises separately fabricating said insulative body and a member from the insulative material embedding said second conductor therein and fixing the member at said insulative body such that said detective capacitor is formed. The second conductor may be formed in the shape of a plate to be wound around the cap body.

Abstract: A misfire-detecting system for an internal combustion engine compares detected sparking voltage with a first predetermined comparative level and a second predetermined comparative level lower than the first predetermined comparative level. Whether a misfire has occurred in the engine is determined based upon a logical relationship between results of the comparisons. As a result, a misfire can be detected accurately even when dielectric breakdown of the mixture occurs while a misfire has occurred.

Abstract: An ignition distributor cap having a first capacitor for detecting ignition voltage of a spark-ignition internal combustion engine to determine if misfire occurs. The ignition distributor cap has a coil contact tower connected to the secondary winding of an ignition coil of the engine, spark plug terminals connected to spark plugs of the engine, and a rotor connecting the coil contact tower to one of the spark plug terminals with a gap to generate an electric path carrying ignition voltage current produced at the ignition coil to the spark plug. In the ignition distributor cap, a conductor is located around the electric path keeping a predetermined distance from the electric path and forming a first capacitor such that the first capacitor constitutes a capacitive divider with a second capacitor for ignition voltage detection between the electric path and the conductor positioned at the coil contact tower or the individual spark plug terminals.

Abstract: A combustion state-detecting system for an internal combustion engine calculates a first average speed by averaging the rotational speed of the engine over a time period corresponding to duration of one stroke of a cylinder, and a second average speed by averaging the rotational speed of the engine over a time period corresponding to duration of one cycle of all strokes of the cylinder. The system calculates a difference between the first average speed and the second average speed, and determines based on the difference whether or not the combustion state of the engine is abnormal.