The present invention generally relates to ignition systems for gasoline engines. More particularly, the invention relates to a discharge ignition apparatus having triggering circuitry that generates a triggering signal based upon stored timing data.
Ignition circuits of relatively elaborate design have often been provided to advance the ignition spark as engine speed is increased. For example, the spark may be delayed at starting speeds until approximately peak compression of the engine""s piston. At higher engine speeds, the spark is preferably advanced to occur before peak compression.
U.S. Pat. No. 5,392,753 to Burson et al., incorporated herein by reference, shows an ignition circuit utilizing a microprocessor.
In one aspect, the present invention provides an ignition apparatus for use with an internal combustion engine to produce an electrical spark at a spark ignition device. The apparatus comprises a magnet assembly, including a pair of pole faces, operatively revolved along a circular path. A magnetically permeable core is mounted adjacent to the circular path and has at least two leg portions each including a respective end face. The leg portions of the magnetically permeable core are situated such that the pole faces pass proximate to the end faces during revolution of the magnet assembly. As a result, a time-varying magnetic flux is produced in the magnetically permeable core.
The ignition apparatus further includes a transformer having a primary coil and a secondary coil related by a predetermined step-up ratio. The secondary coil is electrically connected during operation to the spark ignition device. A spark generation circuit is operative to apply a primary voltage pulse to the primary coil responsive to a triggering signal. The primary voltage pulse produces a spark generating pulse in the secondary coil.
In addition, the ignition apparatus includes triggering circuitry having a processor with stored timing data. The processor is operative to receive a signal indicative of the rotational position of the magnet assembly and produce a triggering signal. In a first mode, the triggering signal occurs at a fixed angle relative to top dead center. In a second mode, the triggering signal occurs at a variable angle relative to top dead center based on the stored timing data.
Other objects, features and aspects of the present invention are discussed in greater detail below.