Internal combustion engine ignition device

An internal combustion engine ignition device having a permanent magnet attached to a rotor connected to a crankshaft of an internal combustion engine so that a magnetic path is formed using the permanent magnet, the ignition device comprising a core, an induced power generation coil wound over the core, a secondary coil coaxially wound on the induced power generation coil, a switching element that turns on and off the induced current generated in the induced power generation coil via rotation of the permanent magnet, a microcomputer connected to the switching element, and a rotation detection circuit connected to the microcomputer, wherein:

• the microcomputer drives the switching element to rapidly change the current flowing through the induced power generation coil and generate a high voltage in the secondary coil, and carries out ignition by generating spark discharge in a spark plug connected to the secondary coil to partially utilize the induced power induced in the induced power generation coil as a drive source of the microcomputer, and the power for allowing the rotation detection circuit to generate pulses;
• a primary current detection means is formed by connecting the microcomputer and a resistor connected between the switching element at a current discharge side and a ground;
• and
• the microcomputer controls the switching element so as to allow the spark plug to have ignition in a range where the crankshaft rotates so that the primary current value detected by the primary current detection means becomes equal to or larger than a minimum value of the primary current value, which ensures ignition.

An internal combustion engine ignition device having a permanent magnet attached to a rotor connected to a crankshaft of an internal combustion engine so that a magnetic path is formed using the permanent magnet, the ignition device comprising a core, an induced power generation coil wound over the core, a secondary coil coaxially wound on the induced power generation coil, a switching element that turns on and off the induced current generated in the induced power generation coil via rotation of the permanent magnet, a microcomputer connected to the switching element, and a rotation detection circuit connected to the microcomputer, wherein:

• the microcomputer drives the switching element to rapidly change the current flowing through the induced power generation coil and generate a high voltage in the secondary coil, and carries out ignition by generating spark discharge in a spark plug connected to the secondary coil to partially utilize the induced power induced in the induced power generation coil as a drive source of the microcomputer, and the power for allowing the rotation detection circuit to generate pulses;
• a primary current detection means is formed by connecting the microcomputer and a resistor connected between the switching element at a current discharge side and a ground;
• and
• when the switching element is opened on a phase that the primary current value detected by primary current detection means exceeds a predetermined maximum value of the primary current, the microcomputer controls to open the switching element for a time period shorter than a predetermined opening time period of the switching element in accordance with the rotational speed of the crankshaft.