An engine control device includes an electronic control unit. The electronic control unit is configured to perform a spark discharge with an ignition plug for each cylinder by cutting off energization after elapse of a predetermined period from start of energization to an ignition coil for each cylinder of the engine, to stop the spark discharge caused by the ignition plug for each cylinder after supply of fuel to the engine is stopped when operation of the engine is stopped, and to control an ignition plug so as to stop the spark discharge caused by the ignition plug from a cylinder after a rotation speed of a crankshaft decreases gradually and the rotation speed of the crankshaft reaches a preset threshold value or less, after the stop of the supply of fuel to the engine.

A current control circuit for an ignition system (i.e., igniter current limiter) is disclosed. The current control circuit can reduce a coil current over a soft shut down (SSD) period using an insulated gate bipolar transistor (IGBT) that is controlled by a negative feedback loop, which controls the current limit of the IGBT according to a SSD profile. In order to prevent an unwanted current rise during the soft shut down period, the current control circuit compares a gate voltage of the IGBT to a reference signal and based on the comparison can enable the SSD profile to include a fast ramp. The fast ramp quickly lowers the current limit of the IGBT so that the coil current equals the current limit and can be controlled by the negative feedback loop.

Please substitute the new Abstract submitted herewith for the original Abstract: Energization abnormality of a switch element of an internal combustion engine ignition device is detected appropriately. To this end, in an internal combustion engine ignition device that includes an ignition coil and an ignition plug, the ignition coil includes a primary coil including a main primary coil and a sub primary coil and a secondary coil that generates secondary current in response to a voltage variation generated in the primary coil. The internal combustion engine ignition device includes a main switch element that performs energization/deenergization of the main primary coil in a first direction, a sub primary coil magnetic flux generation state switching unit capable of switching between a forward direction magnetic flux generation state in which energization of the sub primary coil in the first direction is performed and an opposite direction magnetic flux generation state in which energization of the sub primary coil in a second direction is performed, and an abnormality detection section that detects energization abnormality to the sub primary coil. The abnormality detection section is configured so as to detect energization abnormality on the basis of overlap between energization in the first direction and energization in the second direction of the sub primary coil.

An ignition system for an internal combustion engine includes an ignition coil forming a part of a primary circuit and a secondary circuit, a power source to supply power to the ignition coil, and a controller to determine whether the ignition coil is a recognized ignition coil based on a measured risetime and a measured current level in the primary circuit, the measured current level being lower than that required to create a breakdown voltage of the ignition coil.

An ignition device for igniting an air-fuel mixture in a combustion chamber, in particular an internal combustion engine, having a spark plug, which has a first electrode and a second electrode, and a high voltage source for generating an electrical high voltage pulse at an output of the high voltage source and having a high frequency voltage source for generating an electrical high frequency alternating voltage at an output of the high frequency voltage source, wherein the output of the high voltage source is electrically connected to the first electrode of the spark plug via a first electrical conductor path such that the high voltage pulse is applied to the first electrode, wherein the second electrode is electrically connected to an electrical ground potential, wherein the spark plug has a third electrode, wherein the output of the high frequency voltage source is electrically connected to the third electrode via a second electrical conductor path, such that the high frequency alternating voltage is applied to the third electrode.

Provided is an internal combustion engine ignition device capable of preventing an output signal level of a drive circuit from changing sharply when shifting from a normal ignition operation mode to a protection operation mode while reducing the cost of dedicated components and the like. An internal combustion engine ignition device of the present invention includes a first differential circuit for outputting a drive signal in a first mode and a second differential circuit for outputting a drive signal in a second mode, where the first differential circuit and the second differential circuit each include a transistor and are configured such that a drive current for supplying the drive signal flows through the transistor which is common between the first mode and the second mode.

Provided is an internal combustion engine ignition device capable of preventing an output signal level of a drive circuit from changing sharply when shifting from a normal ignition operation mode to a protection operation mode while reducing the cost of dedicated components and the like. An internal combustion engine ignition device of the present invention includes a first differential circuit for outputting a drive signal in a first mode and a second differential circuit for outputting a drive signal in a second mode, where the first differential circuit and the second differential circuit each include a transistor and are configured such that a drive current for supplying the drive signal flows through the transistor which is common between the first mode and the second mode.

Circuits and methods to control a current in a coil are disclosed. The circuit and methods provide over-dwell protection and soft shut-down functionality to safely discharge the coil. The safe discharge of the coil is facilitated by a soft-start ramp signal that reduces the coil current gradually by controlling a switching device according. A profile of the soft-start ramp signal over time determines the gradual reduction. The profile of the soft-start ramp signal can be adjusted to set (i) an over-dwell period of the coil current, after which the coil current is shut down, and (ii) a soft shut-down period, over which the coil current is gradually reduced.

Circuits and methods to control a current in a coil are disclosed. The circuit and methods provide over-dwell protection and soft shut-down functionality to safely discharge the coil. The safe discharge of the coil is facilitated by a soft-start ramp signal that reduces the coil current gradually by controlling a switching device according. A profile of the soft-start ramp signal over time determines the gradual reduction. The profile of the soft-start ramp signal can be adjusted to set (i) an over-dwell period of the coil current, after which the coil current is shut down, and (ii) a soft shut-down period, over which the coil current is gradually reduced.

An engine control device includes an electronic control unit. The electronic control unit is configured to perform a spark discharge with an ignition plug for each cylinder by cutting off energization after elapse of a predetermined period from start of energization to an ignition coil for each cylinder of the engine, to stop the spark discharge caused by the ignition plug for each cylinder after supply of fuel to the engine is stopped when operation of the engine is stopped, and to control an ignition plug so as to stop the spark discharge caused by the ignition plug from a cylinder after a rotation speed of a crankshaft decreases gradually and the rotation speed of the crankshaft reaches a preset threshold value or less, after the stop of the supply of fuel to the engine.