Engine ignition system with voltage monitoring

US4181113A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Walter Ruf · Ditzingen, DE
• Heinz Krauss

Key dates

• Filing date: Oct 26, 1977
• Grant date: Jan 1, 1980
• Expiry date: Oct 26, 1997

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F02B1/04
• WIPO field: Engines, pumps, turbines
• WIPO sector: Mechanical engineering

Abstract

A voltage divider across the interruptor switch contacts provides a measure of the high voltage produced before a spark occurs at the sparkplug. A Zener diode connected to the upper tap of the voltage divider breaks down when this voltage has risen a certain amount as the result of wear of the sparkplug electrodes that widen the gap. The Zener voltage breakdown causes a relay to lock in and to short-circuit a current-limiting resistor in the spark coil primary circuit that allows a higher voltage spark to be produced to assure proper firing of the sparkplugs with the wider gap. Another Zener diode is connected to the lower tap of the voltage divider to sound an alarm and to disable the ignition circuit when the high voltage at which sparks strike in the sparkplug rises to a value for which the insulation of the spark coil and its connection is not designed to withstand.