Ignition apparatus for an internal combustion engine

Abstract

An ignition apparatus for an internal combustion engine includes a reduced number of component parts which can be arranged or laid out without difficulty within a limited space such as a vehicle engine room. The apparatus can be manufactured at low costs and it is also highly resistant to electrical noise from adjacent electrical and electronic elements and hence has improved reliability in operation. The apparatus includes an ignition coil connected to a spark plug which has electrodes present in a combustion chamber of a cylinder, a switch unit for controlling power supply to the ignition coil, and an ion current sensing unit connected to the spark plug for sensing an ion current generated between the electrodes of the spark plug during combustion of a mixture in the combustion chamber. The ignition coil and the switch unit, or the ion current sensing unit and the switch unit, or all of these elements, are integrally formed with each other to provide an integral assembly. In a preferred form, the switch unit and the ion current sensing unit comprise a hybrid integral circuit. The switch unit includes a switch in the form of a power transistor connected to the ignition coil, and a switch driver for driving the switch. The power transistor can be formed separately from the ion current sensing unit whereas the switch driver can be integrally formed with the ion current sensing unit.

Dependencies are inferred from the claim text.