GB994861A - Internal combustion engine ignition systems - Google Patents

Abstract

994,861. Ignition systems. GENERAL MOTORS CORPORATION. Dec. 5, 1963 [Dec. 6, 1962], No. 48070/63. Heading F1B. In an internal-combustion engine ignition system the supply of current to the primary winding 28 of an ignition coil is controlled by a three terminal semi-conductor switch device 55, 70 which is adapted to be turned on and off by a control device 42 driven in synchronism with the engine and apparatus is included in the system for delaying the turning on of the switch device in accordance with engine speed and the period for which the switch device was turned on during a preceding cycle. The voltage induced in the pick up coil 50 builds up at a slow rate at low engine speeds and at a fast rate at high engine speeds. Accordingly a given charge on capacitor 90 will cause more time delay at low engine speed than at high engine speeds. At low engine speeds the "on" time of transistor 55 tends to be long but this increases the charge on the capacitor 90 supplied from the secondary winding 64 of the coupling transformer and therefore causes the "on" time to be shorter. At high speeds the "on" time of the transistor 55 tends to be short and this causes less charge to be supplied from the secondary winding 64 so that less delay and turn on of the transistor 55 results. Proper choice of circuit components will cause the "on" time of the transistor 55 at low speeds to be only slightly longer than at high speeds. A feedback coil not shown may be provided which is connected between one side of the primary winding 58 and the conductor 32. The term "three terminal semiconductor switch means" is intended to cover transistors and any other three terminal semiconductors such as controlled rectifiers which are capable of being used in place of transistors.