Process and device for monitoring and observation of aging of a catalytic converter in exhaust gas of internal combustion engines and of emission of hazardous materials

摘要

The major part of the hazardous material quantities emitted by motor vehicles having an exhaust gas catalytic converter accrues in the start-up phases in which the catalytic converter is not yet at the operating temperature. The catalytic converter first begins to operate after it is heated up to the light-off temperature. The heat-up times must be kept as short as possible. With aging of the catalytic converter, the light-off temperature gradually increases, and thus, the heat-up time as well as the emitted hazardous material quantity also increases. In order to monitor the catalytic converter and thus the major part of the hazardous material emission, the light-off temperature must be repeatedly measured. Since this temperature cannot be read out clearly from the temperature-time curve of the catalytic converter after the start-up of the motor, the signal of a sensor for oxygen, carbon dioxide, water vapor, or combustible materials in the exhaust gas is additionally observed. At the moment of the light-off of the catalytic converter, the signals of these sensors change rapidly, such that the light-off time and thus the light-off temperature of the catalytic converter can be exactly determined. Suitable devices for external use in workshops or monitoring stations, as well as for on board installation, are given. The continuous storage of the sensor-indicated light-off temperatures and light-off times is expedient in order to observe the gradual aging of the catalytic converter until it has reached an intolerable state.