Patent ID: 6526953
Filing Date: 2003-03-04
Classification: F02P

Abstract:
An ignition unit for an internal combustion engine comprising:an ignition coil including a primary wiring connected to a power source unit and a secondary wiring forming a closed loop together with a spark plug equipped in the internal combustion engine, a spark discharge generating means for energizing current from the power source unit to the primary wiring of the ignition coil synchronously with the rotation of the internal combustion engine and for generating high voltage for ignition in the secondary wiring by interrupting the energizing current to thereby make the spark plug perform spark discharge, a primary wiring short-circuiting means for short-circuiting both ends of the primary wiring of the ignition coil in the correspondence to instructions from an instruction means, a spark discharge duration calculating means for calculating a spark discharge duration required for combusting mixed gas through spark discharge of the spark plug based on an operating condition of the internal combustion engine, the spark discharge duration being calculated to be long under the low-load and low rotation condition of the internal combustion engine and the same being calculated to be short but equal to or more than 0.2 msec under the high-load and high-rotation condition of the internal engine, and a spark discharge interrupting means for forcibly interrupting spark discharge of the spark plug by short-circuiting both ends of the primary wiring of the ignition coil by actuating the primary wiring short-circuiting means in accordance with the spark discharge duration calculated by the spark discharge duration calculating means.