Method and arrangement for determining the internal resistance of a lambda probe and for the closed-loop heating control with the aid of the internal resistance

US5291417A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Eberhard Schnaibel · Hemmingen, DE
• Lothar Raff · Waiblingen, DE
• Michael Westerdorf · Asperg, DE
• Manfred Homeyer · Markgröningen, DE

Key dates

• Filing date: Apr 22, 1991
• Grant date: Mar 1, 1994
• Expiry date: Apr 22, 2011

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F02D41/1476
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The internal resistance of a lambda probe is determined by: the application of a clocked direct-current counter voltage to the probe via a series resistor; the measurement of the output voltages with the counter voltage connected and disconnected; and, the calculation of the internal resistance from the measured values and known resistance values. Apart from the components of a conventional arrangement, this method requires only a series resistor and a switch for implementation. Measurement can be carried out at short time intervals without excessively high direct-current voltage loading which affects the service life. The internal resistance measured is compared with a desired resistance and the control deviation determined in this way is used to determine the duty factor for probe heating clocked with fixed frequency.