Method of controlling the air-fuel ratio in an internal combustion engine

US4492205A · kind A · utility

Inventors

• Werner Jundt · Ludwigsburg, DE
• Rolf Reischl · Stuttgart, DE

Key dates

• Filing date: Oct 14, 1982
• Grant date: Jan 8, 1985
• Expiry date: Oct 14, 2002

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F02D41/148
• WIPO field: Engines, pumps, turbines
• WIPO sector: Mechanical engineering

Abstract

To prevent stumbling operation of an internal combustion (IC) engine (E) during warm-up due to switching back-and-forth between control of the air-fuel composition of the mixture being applied to the engine based on a preset, rich mixture and controlled by a lambda sensor, the lambda sensor internal resistance is sensed and, when the internal resistance of the lambda sensor, when exposed to a rich mixture, is substantially less than when exposed to a fuel-lean mixture, an indication is thereby provided that the sensor has reached proper operating temperatures - see FIG. 3 - is capable of providing output voltages within the evaluation range of two threshold circuits (9, 10) which receive reference values from a voltage divider (6, 7, 8) and of resuming control based on the output voltages of the sensor. The minimum operating temperatures of the sensor are asymmetrical, with respect to lean or rich air-fuel mixtures being applied to the engine, to permit either uninterrupted control of the engine in accordance with a preset air-fuel mixture during warm-up or only by the sensor, after it has reached its operating temperature, thereby preventing back-and-forth switching between contro…