Ignition coil with overvoltage protection connected to the secondary winding of the ignition coil

US4351310A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Karl-Heinz Adler · Leonberg, DE
• Georg Pfaff · Schifferstadt, DE
• Reinhard Leussink · Leinfelden, DE
• Gerhard Sohner · Schorndorf, DE
• Gerd Hohne · Ludwigsburg, DE
• Thomas Jokh · Ditzingen, DE
• Heinz Decker · Leinfelden, DE

Key dates

• Filing date: Oct 1, 1980
• Grant date: Sep 28, 1982
• Expiry date: Oct 1, 2000

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F02P3/0552
• WIPO field: Engines, pumps, turbines
• WIPO sector: Mechanical engineering

Abstract

An overvoltage protection circuit is galvanically, directly connected across at least part of the secondary winding in the ignition system of an internal combustion engine. The input portion of the overvoltage protection circuit is a voltage divider preferably constituted by RC elements. The voltage at the tap of the voltage divider is applied to a Schmitt trigger. When the voltage across the secondary winding becomes excessively high, the Schmitt trigger output pulse triggers a monostable multivibrator whose output pulse in turn increases the conductivity of a transistor switch located in series with the primary. The increase in primary current tends to oppose further increases in primary and secondary voltages. Alternatively, the output from the multivibrator could be used to shorten the time of current flow in the primary winding in subsequent ignition time intervals or to completely block any subsequent ignition process.