A method is described for determining the resistance temperature characteristic of a ceramic glow plug, wherein the glow plug is heated at a specified power, wherein before the heating it is first determined whether the glow plug is an aged glow plug, and then, if the glow plug has not been detected as an aged glow plug, the glow plug is heated at a first specified power and the resistance value thereby achieved is assigned to a temperature that is anticipated to be the final temperature when heating a factory-outlet glow plug at this first power, or if the glow plug has been detected as an aged glow plug, the glow plug is heated at a reduced power which is smaller than the first power, and the resistance value achieved thereby is assigned to the same temperature that is also anticipated when heating a factory-outlet glow plug at the first power.

A method is described for determining the resistance temperature characteristic of a ceramic glow plug, wherein the glow plug is heated at a specified power, wherein before the heating it is first determined whether the glow plug is an aged glow plug, and then, if the glow plug has not been detected as an aged glow plug, the glow plug is heated at a first specified power and the resistance value thereby achieved is assigned to a temperature that is anticipated to be the final temperature when heating a factory-outlet glow plug at this first power, or if the glow plug has been detected as an aged glow plug, the glow plug is heated at a reduced power which is smaller than the first power, and the resistance value achieved thereby is assigned to the same temperature that is also anticipated when heating a factory-outlet glow plug at the first power.

A control apparatus, which is for an internal combustion engine with a spark plug having a center electrode and a ground electrode disposed so as to form a spark discharge gap therebetween, includes a voltage applying section for applying a voltage to the spark discharge gap, a constant-voltage path including a constant-voltage element parallel-connected to the spark discharge gap of the spark plug for preventing the spark discharge gap from being applied with a voltage higher than a set voltage, and an operation control circuit for controlling an operating condition of the internal combustion engine. The operation control circuit is configured to measure a current-flowing time during which a current flows through the constant-voltage path when a voltage higher than the set voltage is applied to the constant-voltage path, and change the operating condition of the internal combustion engine in accordance with the measured current-flowing time.

An ignition apparatus for an internal combustion engine includes: a spark plug; a first ignition coil and a second ignition coil; a battery; a booster circuit that boosts a voltage supplied from the battery; a power transistor that conducts and interrupts a primary current flowing to a primary coil included in the first ignition coil; a MOSFET that applies and interrupts the voltage boosted by the booster circuit to a primary coil included in the second ignition coil; and an ECU that starts electric discharge by the spark plug by controlling the power transistor, and repeatedly applies and interrupts the voltage boosted by the booster circuit by the MOSFET so that the electric discharge that is started is maintained.

An engine system for a vessel propulsion device includes an engine including an intake amount adjusting unit and an ignition plug, and configured to generate a drive force for the vessel propulsion device. The engine system includes an ignition timing control unit, a knocking detecting unit, a knocking retard control unit that retards the ignition timing of the ignition plug by a unit retard amount when the knocking detecting unit detects knocking, an abnormality judging unit that, when a state where the knocking detecting unit detects knocking at intervals within a predetermined time continues, judges that an abnormality has occurred based on a continued state of knocking detection, and an intake amount limiting unit that limits the intake amount of the engine based on judgment of an abnormality made by the abnormality judging unit.

A system for testing an insulative material for a spark plug comprises a test spark plug having at least a center electrode and an insulator comprised of an insulative material surrounding at least a portion of the center electrode, wherein the insulator has an end that is closed, whereby the closed end of the insulator encloses an end of the center electrode. The system further includes a test engine that simulates engine conditions, wherein a conventional spark plug is installed in a first ignition port of the test engine and the test spark plug is installed in a second ignition portion of the test engine and a control system for controlling ignition signals to the test spark plug and the conventional spark plug.

A system for testing an insulative material for a spark plug comprises a test spark plug having at least a center electrode and an insulator comprised of an insulative material surrounding at least a portion of the center electrode, wherein the insulator has an end that is closed, whereby the closed end of the insulator encloses an end of the center electrode. The system further includes a test engine that simulates engine conditions, wherein a conventional spark plug is installed in a first ignition port of the test engine and the test spark plug is installed in a second ignition portion of the test engine and a control system for controlling ignition signals to the test spark plug and the conventional spark plug.

A method for controlling an internal combustion engine. Target ignition times for the individual cylinders are given by an engine control device through trigger signals transmitted to the ignition control device. After receiving a trigger signal, the ignition control device activates the ignition device associated with this trigger signal to effect ignition in the respective cylinder. The ignition control device stores a firing order in which an ignition is to be cyclically effected in the individual cylinders, and it is checked whether trigger signals for all cylinders are received in the stored firing order, and if not, a substitutional ignition time is calculated for the at least one cylinder for which no trigger signal has been received, from at least two trigger signals for the cylinders or one of the remaining cylinders, and the respective ignition device or ignition devices are activated according to the calculated substitutional ignition time.

A method for controlling an internal combustion engine. Target ignition times for the individual cylinders are given by an engine control device through trigger signals transmitted to the ignition control device. After receiving a trigger signal, the ignition control device activates the ignition device associated with this trigger signal to effect ignition in the respective cylinder. The ignition control device stores a firing order in which an ignition is to be cyclically effected in the individual cylinders, and it is checked whether trigger signals for all cylinders are received in the stored firing order, and if not, a substitutional ignition time is calculated for the at least one cylinder for which no trigger signal has been received, from at least two trigger signals for the cylinders or one of the remaining cylinders, and the respective ignition device or ignition devices are activated according to the calculated substitutional ignition time.

There are provided a plug built-in type optical measurement probe capable of obtaining a more accurate measurement value, and an optical measurement device provided with the same. A spark section and a light receiving section are held by a plug main body while being arranged next to each other in a protruding manner such that an end face of a holder is arranged at a position where discharge light from the spark section does not enter the field of view of the light receiving section. Accordingly, the light receiving section can be held in a manner protruding from the plug main body, and entering of the discharge light from the spark section can be restricted by the holder of the light receiving section. That is, by arranging the end face of the holder at a position where the discharge light from the spark section does not enter the field of view of the light receiving section, the light receiving intensity of the discharge light from the spark section can be prevented from being added to a measurement value, and it is possible to measure only the light generated at the time of combustion, and thus, a more accurate measurement value can be obtained.