Connecting circuit for connecting a lambda probe to a control apparatus of an internal combustion engine and test method for said circuit

US5298865A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Helmut Denz · Stuttgart, DE
• Werner Mezger · Weinsberg, DE
• Johannes-Dieter Wichterich · Hemmingen, DE
• Ernst Wild · Oberriexingen, DE
• Joachim Heimes · Markgröningen, DE
• Eugen Joos · Freiberg, DE
• Lothar Raff · Waiblingen, DE
• Eberhard Schnaibel · Hemmingen, DE

Key dates

• Filing date: Apr 24, 1992
• Grant date: Mar 29, 1994
• Expiry date: Apr 24, 2012

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N27/4175
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The invention is directed to a connecting circuit for a potential-free lambda probe having a ground line and a signal line and having an offset voltage source which is connected to the ground line. This offset voltage source raises the potential of the ground line to a pregiven value relative to ground. A ground short is directly detectable in the connecting circuit of the invention in that the potential measured at the signal line drops below the offset voltage. In this way, it is no longer required as in conventional circuits to check for a ground short by enriching the mixture of an engine and to monitor the exhaust gas with the lambda probe.