Vdo Adolf Schindling Ag

Peter Olejnik

Ulrich Staufenberg

A method for controlling the fuel-air ratio of an internal combustion engine in which the output signal of a first lambda probe, which is arranged in front of a catalytic converter in the exhaust pipe of the internal combustion engine, is fed to a controller. The controller gives off a setting variable for the fuel-air ratio, and a further signal which is obtained from the output signal of a second lambda probe arranged behind the catalytic converter is fed to the controller. In order to permit an accurate and adjustable control which further improves the fuel-air ratio in the sense of a reduction of the exhaust emission, a hold time is obtained on the output signal of the second lambda probe as a function of the time of the reversal of the output signal of the first lambda probe, whereby the output signal of the controller is shifted in time.

Method for controlling the fuel-air ratio of an internal combustion

A method for the calibration of a lambda probe in an internal combustion engine in which the lambda probe is arranged in front of and/or behind a catalytic converter in order to control a fuel-air mixture of the internal combustion engine. The lambda probe gives off signal values during a measurement period as a function of the exhaust gas produced from the fuel-air mixture. In order to compensate for the lack of sharpness resulting from a manufacturing process of the lambda probe and an aging of the probe, a method is proposed for the calibration of the lambda probe in which the catalytic converter is supplied with an overly rich fuel-air mixture. During this time the corresponding signal measurement values of the lambda probe are measured independently of other control signals. Upon a further processing of the probe signal, a correction value is formed therefrom, which correction value is fed to the probe signal in the controlled operating state of the internal combustion engine.

Method for the calibration of a lambda probe in an internal combustion

A method of checking the efficiency of a catalytic converter in an internal combustion engine in which a ratio is formed from the amplitude of the output signal of a lambda probe arranged behind the catalytic converter and from the amplitude of the output signal of a lambda probe arranged in front of the catalytic converter. The ratio is compared with a threshold value, the catalytic converter being recognized as deficient if the ratio is less than the threshold value. In order to compensate for the lack of sharpness resulting from the manufacturing process and the aging of the probe, the method provides for determining the efficiency of the catalyst in which an extreme value of the corresponding probe output signal is determined for each probe after each probe reversal.

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Bad Soden, Germany

Peter Olejnik