Low-speed compensated ignition system for an internal combustion engine

US4356808A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Bernd Bodig · Leinfelden, DE
• Werner Jundt · Ludwigsburg, DE

Key dates

• Filing date: Nov 2, 1981
• Grant date: Nov 2, 1982
• Expiry date: Nov 2, 2001

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F02P3/0453
• WIPO field: Engines, pumps, turbines
• WIPO sector: Mechanical engineering

Abstract

A switching transistor (7, 9) is serially connected with the primary (5) of an ignition coil; current flow therethrough is controlled from an a-c signal generator (16) with respect to an ON threshold level (Ue) to store electromagnetic energy, and an OFF threshold level (Ua) to generate a spark; a variable conductivity circuit (26) controlled from a sensing resistor (8) modifies the response level of the threshold switch (13) with respect to the null or cross-over level of the applied signal. To prevent excessive current flow under idle-speed conditions, in accordance with the invention, the ON threshold level, at least, of the switch is shifted by introducing an auxiliary bias voltage derived from an auxiliary capacitor (36) and connected (37, 38) by the signal source through a diode (38) which prevents application of an auxiliary bias voltage to the threshold switch (13) under extremely low, e.g. starting conditions, permits application of the additional bias voltage providing for shift of the ON response level (Ue) under idling conditions, but again loses control as the speed continues to increase, and control by the variable conductivity circuit takes over.