Method for adjusting a defined oxygen concentration by means of binary lambda regulation in order to diagnose an exhaust gas catalyst

US7343734B2 · kind B2 · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Reza Aliakbarzadeh · Regensburg, DE
• Gerd Rösel · Dresden, DE
• Milos Tichy · Griesheim, DE

Key dates

• Filing date: Jan 15, 2004
• Grant date: Mar 18, 2008
• Expiry date: Mar 26, 2025

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F02D2200/0816
• WIPO field: Engines, pumps, turbines
• WIPO sector: Mechanical engineering

Abstract

The invention relates to a method for diagnosing a regulated exhaust gas catalyst, according to which regulating the catalyst results in control cycles, catalyst diagnosis being performed at a predetermined oxygen concentration per control cycle. A fuel mixture can be adjusted fat or lean according to a specific lambda control factor. A fat or lean exhaust gas is detected, the lambda control factor being incrementally decreased when a lean exhaust gas is detected. The lambda control factor is modified by a P step following a detected change from a fat to lean exhaust gas or from a lean to a fat exhaust gas, the lambda control factor being set to a minimum value during a first loading period following a detected change from a fat exhaust gas to a lean exhaust gas while being set to a maximum value during a second loading period following a detected change from a lean exhaust gas to a fat exhaust gas. The first and the second loading period are adjusted such that the oxygen concentration reaches the predetermined oxygen concentration in each control cycle.