MOTORING

Hawera Star, Volume XLVII, 2 June 1928, Page 15

MOTORING

BATTERY IGNITION.

FUNCTIONS OF SYSTEM

Functions of the various parts or a battery ignition system in a motor vehicle are compared with a truckdriver and the truck by Dr. F. 13. Silsliee, of the United .States Bureau of .standards. The building up of energy in the primary circuit is similar lie said, to the storing up of energy in the engine flywheel when the driver “steps on the gas” with the clutch disengaged. When the clutch is engaged this energy gives an impulse to the rear wheels. Similarly, when the primary circuit I is broken by the commutator, a high voltage impulse is induced ill the secondary circuit' and causes the electric current to jump from one electrode of j the .spark plug to the other, causing the spark that ignites the.charge in the engine cylinder. The spark lasts only about 1-1000th of a second for battery ignition and about 3-1000ths fcr magnet ignition. In this interval an oscillation of the 1 current and voltage occurs in the secondary circuit, and this oscillation has a. duration of only 1-1,000,000 th of a second, said Dr. Silsbee. The current then settles to a value of approximately 50 milliamperes, and the voltage drops from 4000 to 800. Next there is a decrease in quantity of the current flowing between the spark plug points until the spark becomes extinct. Sparking voltage is- increased by widening the gap between the points and by density of the compressed charge in the cylinder. Increases in temperature or in the sharpness of the {mints lowers the sparking voltage. lons such as are demonstrated by the recently discovered Milliken rays must he present in the cylinder before a spariv can r.erur, as they are the carriers of the electric current.

Much less ignition trouble- would occur, said the speaker, if spark coil manufacturers would make the coils so that, they would deliver both higher current and voltage, so that more energy would he effective.