Device for regulating the fuel-air ratio in internal combustion engines

US4393841A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Ulrich Drews · Schwieberdingen, DE
• Peter Werner · Wiernsheim, DE
• Werner Mohrle · Stuttgart, DE

Key dates

• Filing date: Jun 24, 1981
• Grant date: Jul 19, 1983
• Expiry date: Jun 24, 2001

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N27/4065
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A device is proposed for regulating the fuel-air ratio in the operating mixture of an internal combustion engine and for monitoring the operational readiness of a .lambda. sensor controlling the regulating device and functioning by the principle of ion conduction in solid electrolytes. The .lambda. sensor has an adjustable, constant reference voltage switched opposite to it. The reference voltage approximately equals the average sensor output voltage. The level of the resultant voltage, which is established with the aid of the resultant current and has values located symmetrically with respect to the reference voltage, is monitored by comparator devices. The output signal of the comparator devices is logically processed and furnishes a signal as to the operational readiness of the sensor. In order to generate the reference voltage, a voltage divider branch having high resistance is disposed parallel to a voltage divider branch of relatively low resistance; the latter voltage divider branch further serves to establish the threshold values of the comparator devices. Because it is independent of the current draw of the comparator devices, the desired reference voltage can be adhered t…