초록 ▼

This invention relates to a number of improvements in ignition systems of spark ignition engines. A detector is employed to sense the first or “breakdown”phase of spark discharge across the spark plug which causes a short duration high current flow across the plug gap. The detection of the breakdown

This invention relates to a number of improvements in ignition systems of spark ignition engines. A detector is employed to sense the first or “breakdown”phase of spark discharge across the spark plug which causes a short duration high current flow across the plug gap. The detection of the breakdown current enables control over a number of ignition system functions. A pulse transformer is used which enables extremely short duration energization of the spark plug at controllable voltages. The existence of end gas auto-ignition is detected by energizing the spark plug during a period of the operating cycle after top dead center of piston travel. Since the threshold voltage necessary to generate spark discharge at the plug differs in conditions where auto-ignition is occurring versus ordinary combustion, sensing of plug breakdown during such energization provides a means of detecting the occurrence of auto-ignition. Further, in accordance with this invention, the spark plug may be caused to multiply discharge within a short duration which has been found to increase the lean burn limit of the engine. The system further enables the duty cycle of the pulse transformer to be reduced thus allowing use of smaller and lighter weight pulse transformers. The ignition system also provides a means of sensing abnormal conditions in the combustion chamber via the spark plug. Pre-ignition occurring at the spark plug electrode gap will result in a very low breakdown voltage which is detected as an indication of an abnormal condition.

대표청구항 ▼

An ignition system for a spark ignition internal combustion engne comprising: a pulse transformer having a primary winding and a secondary winding connected to a spark plug; driver means for supplying a voltage signal to said pulse transformer primary winding thereby including a high voltage signal

An ignition system for a spark ignition internal combustion engne comprising: a pulse transformer having a primary winding and a secondary winding connected to a spark plug; driver means for supplying a voltage signal to said pulse transformer primary winding thereby including a high voltage signal and said secondary winding applied to said spark plug; controller means for providing control signals to said driver means, thereby causing said driver means to generate a voltage applied to said secondary winding, and discharge detection means for sensing the occurrence of electrical discharge across said spark plug and applying a discharge signal to said controller means for controlling the operation of said controller means; wherein said ignition system detects the existence of auto-ignition characterized by pressure and temperature fluctuations within said engine combustion chamber occurring after piston top dead center which departs from normal combustion, and further comprising timing means for sensing the position of the piston and for providing a timing signal, and wherein said controller means applies a hover voltage of a predetermined maximum level across said spark plug during a period of the cylinder cycle operating cycle after piston top dead center, said hover voltage applied at a level at which discharge across said spark plug occurs in the event that said combustion chamber is experiencing auto-ignition but does not occur if the conditions within the cylinder are of normal combustion, wherein said discharge detection means thereby provides an indication of the existence of auto-ignition.