Input-output unit for microprocessor controlled ignition or injection systems in internal combustion engines

摘要

An input-output unit carries out some of the operations previously carried out in the microcomputer controlling the ignition, injection, etc. processes so that the number of bits in the microprocessor can be reduced. The input-output unit includes a counter which furnishes speed- dependent or angle-dependent signals. During a predetermined angle of rotation or while a particular speed-dependent value is counted and down, a frequency proportional to the quantity of air in the air inlet is counted, the resultant air number transferred to the microprocessor where it is modified. The modified air number can be counted down in the same counter which was used to count down the speed- dependent signals. The time required for counting down the modified air number determines the injection time and/or the closing time for an electronic switch in the primary circuit of the ignition coil. When the angle-dependent signal is used, a further counter counts down the air number several times, each time generating an interrupt signal. The latter count is in the microprocessor and when a predetermined number has been received, the microprocessor furnishes a terminate signal ending the controlled process.