A new ignition timing control method using dual-slope integration

A potentially useful method of reducing pollutants in automobile exhaust gas and reducing fuel consumption is the optimum control method for ignition timing of the mixture. Optimum ignition timing varies with the state of engine operation. Moreover, it is a complex function involving parameters of engine operating state. Ignition timing is usually expressed as the measure of angular displacement of the engine shaft with varying rotational speed, so that its control must depend on continuous phase control techniques. Dual-slope integration as a method of this phase control is proposed. A special feature of this method is that the phase angle between signals for each reference angle input intermittently can be determined in terms of linear functions of repetition frequency of the signals. By varying the time constants of integration and the level of comparison with the integration value, even more complex multivariant functions can be generated. The principle of phase control by dual-slope integration is described. An ignition timing controller applying this principle is discussed, the controller meeting the optimum ignition timing characteristics required in actual automobiles.