An internal combustion engine control apparatus includes: an ignition coil including a primary coil and a secondary coil that are magnetically coupled to each other; a first switch element for turning on and off a current to the primary coil; and a spark plug, for igniting an air-fuel mixture in an internal combustion engine by using a spark discharge caused by switching the first switch element from the ON state to the OFF state. The internal combustion engine control apparatus is configured to: determine occurrence of one of an abnormality in a discharge voltage and a misfire of the spark plug, when the calculated time duration in which a voltage of the primary coil after the switching of the first switch element from the ON state to the OFF state is above a predetermined comparison reference voltage does not fall within an allowable range.

An igniter includes a switch element and a switch control apparatus. An ignition signal IGT is input to an input line of the switch control apparatus. A high-frequency filter removes high-frequency noise from the input line. A voltage comparator compares an output voltage V.sub.FIL of the high-frequency filter with a reference voltage V.sub.REF, so as to generate a judgment signal S.sub.DET. A driving stage controls an on/off switching operation of the switch element according to the judgment signal S.sub.DET. An off-state dead-time circuit prohibits the switch element from turning off during a predetermined dead time after the judgment signal S.sub.DET transits to a negated level that corresponds to the off state of the switch element.

An igniter includes a switch element and a switch control apparatus. An ignition signal IGT is input to an input line of the switch control apparatus. A high-frequency filter removes high-frequency noise from the input line. A voltage comparator compares an output voltage V.sub.FIL of the high-frequency filter with a reference voltage V.sub.REF, so as to generate a judgment signal S.sub.DET. A driving stage controls an on/off switching operation of the switch element according to the judgment signal S.sub.DET. An off-state dead-time circuit prohibits the switch element from turning off during a predetermined dead time after the judgment signal S.sub.DET transits to a negated level that corresponds to the off state of the switch element.

The invention, while reducing noise, suppresses a load increase in a processor and a delay in drive control. An engine control unit includes a processor, a driving circuit including a switching element to drive a load such as a fuel injector and an ignition device, and a communication circuit that transmits control signals from the processor to the driving circuit via serial communication. The control signals each include a command frame for controlling the driving circuit and a data frame for driving the load. If a predetermined bits in each of the data frames received from the processor at predetermined time intervals are determined to be the same twice in succession, the engine control unit changes a state of a driving signal ‘Drive’ for driving the load and thereby changes an operating state of the switching element.

An igniter semiconductor device and an igniter system can prevent the influence of a voltage drop of an ON signal voltage input to an input terminal and the influence of a surge voltage, allow a switching element to operate reliably, and prevent an ignition failure. The igniter semiconductor device includes an external terminal including at least an input terminal, an output terminal electrically connected to an ignition coil, a ground terminal, and a power supply terminal electrically connected to a regulated power supply wire outside the igniter semiconductor device. The ignited semiconductor device further includes a switching element for controlling current flowing in the ignition coil, and a driving circuit that receives power through the power supply terminal and drives the switching element based on a signal input from the input terminal.

An igniter semiconductor device and an igniter system can prevent the influence of a voltage drop of an ON signal voltage input to an input terminal and the influence of a surge voltage, allow a switching element to operate reliably, and prevent an ignition failure. The igniter semiconductor device includes an external terminal including at least an input terminal, an output terminal electrically connected to an ignition coil, a ground terminal, and a power supply terminal electrically connected to a regulated power supply wire outside the igniter semiconductor device. The ignited semiconductor device further includes a switching element for controlling current flowing in the ignition coil, and a driving circuit that receives power through the power supply terminal and drives the switching element based on a signal input from the input terminal.

In an ignition coil for an internal combustion engine, a resistor is disposed in a tower insertion hole of a high-voltage tower section. A coil spring is inserted in the tower insertion hole. An inner diameter of a proximal end side portion of the tower insertion hole is larger than an outer diameter of a maximum outer diameter portion of the resistor. An inner diameter of the distal end side portion of the tower insertion hole is larger than an outer diameter of a proximal end side portion of the coil spring, and is smaller than the outer diameter of the maximum outer diameter portion. In a state where the coil spring is pulled out from the tower insertion hole, the maximum outer diameter portion is restrained by the distal end side portion of the tower insertion hole, and a gap is formed between the resistor and a high-voltage cap.

Provided is a switch apparatus including a conductor; a switching device that contacts the conductor on a first surface and switches between a first terminal on the first surface side and a second terminal on a second surface side that is opposite to the first surface; and a control device that contacts the conductor on a third surface and includes a control circuit of the switching device provided on a fourth surface side opposite to the third surface and a first withstand voltage structure that protects the control circuit from excessive voltage added to the conductor. By providing the withstand voltage structure in the control device, it is possible to protect the control circuit.

An object is to reduce the required numbers of connector pins and A/D converters, without degrading the detection accuracy. There is provided an ignition apparatus which includes: ignition plugs provided for multiple cylinders; an ignition coil provided for each cylinder, and having a primary coil and a secondary coil magnetically coupled to the primary coil and connected to the ignition plug; switching devices each for switching between application and shut-off of current to the primary coil; a primary-voltage-signal separator provided for each cylinder, for inputting thereto a voltage of the primary coil and outputting the voltage as a primary signal; a primary-signal combiner for electrically combining together each primary signal corresponding to each cylinder, to thereby output a composite primary signal; and a primary-voltage-information detector for inputting thereto the composite primary signal, to thereby output primary voltage information of each cylinder.

A first filler resin is disposed to cover at least an outer peripheral side of a secondary spool and a secondary coil. The second filler resin is filled inside a case and seals a cover sealant which includes a primary coil, secondary spool, a secondary coil, a center core, an outer core and the first filler resin. The connector protrudes to an outside of the case. The case has a fixing portion. The second filler resin has a lower elasticity than the first filler resin. The ignition coil is manufactured by filling the first resin inside the case, and filling the second resin after the first resin is cured.