Abstract: A relief device includes a relief housing constituted by a relief inflow portion, a valve passage portion, a recess, and an oil discharge portion having a relief hole; a relief valve having a small-diameter portion between a first large-diameter portion and a second large-diameter portion; and a spring elastically biasing the relief valve toward the relief inflow portion. The recess is formed at a position that is closer to the relief inflow portion side than to the oil discharge portion, the axial length of the recess is larger than the axial length of the first large-diameter portion of the relief valve, and the shortest axial distance between the recess and the relief hole is less than the axial length of the small-diameter portion.

Abstract: A relief device includes a relief housing constituted by a relief inflow portion, a valve passage portion, a recess, and an oil discharge portion having a relief hole; a relief valve having a small-diameter portion between a first large-diameter portion and a second large-diameter portion; and a spring elastically biasing the relief valve toward the relief inflow portion. The recess is formed at a position that is closer to the relief inflow portion side than to the oil discharge portion, the axial length of the recess is larger than the axial length of the first large-diameter portion of the relief valve, and the shortest axial distance between the recess and the relief hole is less than the axial length of the small-diameter portion.

Abstract: A high probability of detecting an erroneous misfire occurs when combustion becomes unstable during jolt control. Therefore, during jolt control the reliability of the misfire detection system is degraded. As a result, the misfire detection system is inactivated during jolt control by discontinuing the misfire detection, or by deliberately deeming no misfire has occurred if jolt control has occurred. Alternatively, the misfire detection sensitivity is masked during jolt control.

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: 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 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: A misfire-detecting system for an internal combustion engine having a plurality of cylinders. A rotational speed of the engine is detected and a rotational speed signal indicative of the detected rotational speed of the engine is output. The rotational speed signal is filtered. Occurrence of a misfire in the engine is determined based on the filtered rotational speed signal.

Abstract: A misfire detecting system for an internal combustion engine, including an intake pipe internal pressure detecting device for detecting an internal pressure of an intake pipe of the internal combustion engine, and a misfire detection inhibiting device for inhibiting the detection of misfire when the internal pressure of the intake pipe detected by the intake pipe internal pressure detecting device is lower than an intake pipe internal pressure in a no-load condition.

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 misfire-detecting system for an internal combustion engine in which a value of sparking voltage is detected, which is generated across a spare plug when high voltage is generated by an ignition device in response to generation of an ignition command signal. When a time period over which the detected value of sparking voltage exceeds a predetermined reference voltage value exceeds a predetermined time period value, the system determines that a misfire has occurred in the engine. A recharging command signal is generated for applying high voltage to the spark plug, after generation of the ignition command signal. As a result, a misfire can be accurately detected.

Abstract: A spark plug cap having a capacitor for detecting ignition voltage of an internal combustion engine to determine if misfire occurs. The spark plug cap covers the terminal of a spark plug and has a conductor for carrying ignition voltage current from an ignition coil to spark plug terminals to generate an electronic spark between spark plug electrodes and an insulator surrounding the conductor. In the spark plug cap, a second conductor is located around the first conductor keeping a predetermined distance from the first conductor such that a capacitor, which constitutes a capacitance divider with a capacitor for ignition voltage detection, is formed between the first and the second conductors. A ceramic insulator may be positioned between the first and the second conductors to provide higher insulation property.

Abstract: A fuel supply control system which controls an amount of fuel supplied to an internal combustion engine. An ECU detects a value related to an amount of combustion ions generated within cylinders. The detected value is compared with a predetermined value, and the amount of fuel supplied to the engine is corrected based upon the comparison result, when the engine is in a transient operating condition, such as acceleration and deceleration, whereby the responsiveness of the air-fuel ratio feedback control is enhanced to improve drivability and exhaust emission characteristics.

Abstract: A high tension cord cover disposed at an engine cylinder head for covering a groove in which high tension cords pass through for supplying an ignition voltage current to a spark plug of the engine. The cover is made of an insulation material and having a cord retaining section at the bottom surface facing the groove for retaining the cords in parallel with each other. A plate like conductor is embedded in the cover 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 cores of the high tension cords and the plate like conductor. The conductor can be electrically shielded. A second member made of an insulation material can be provided in the groove underneath the cover for retaining the cords such that the conductor embedded in the cover is kept the predetermined distance from the cords.

Abstract: A misfire-detecting system detects a misfire occurring in an internal combustion engine. A value of sparking voltage for discharging a spark plug of the engine is detected. A differentiating circuit differentiates the detected value of the sparking voltage. A misfire-determining circuit compares the differential value of the sparking voltage with a predetermined value, and determines, based upon a result of the comparison, whether a misfire has occurred in the engine.

Abstract: A misfire-detecting system for an internal combustion engine carries out self-diagnosis of the system. In the system, sparking voltage generated across a spark plug of a cylinder of the engine is detected, and the detected sparking voltage is compared with a first predetermined reference voltage value, and a time period is measured over which the detected sparking voltage exceeds the first predetermined reference voltage value. It is determined that a misfire occurred in the engine when the measured time period exceeds a predetermined time period value. It is determined whether the engine is in self-sustaining operation. When it is determined that the engine is in self-sustaining operation, it is determined whether the misfire-detecting system is abnormal. It is determined that the misfire-detecting system is abnormal when the detected sparking voltage is lower than a second reference voltage value.