Model Based Knock Detection

Abstract

The Model Based Knock Detection (MBKD) is an innovative method to identify knocking combustions and pre-ignitions in gasoline engines. The MBKD was a joint development by the specialized calibration team and the function development team for knock detection and control at Robert Bosch GmbH. The overall objective of the MBKD is to increase quality and to reduce the effort required for the parameterization of the individual methods that serve to identify abnormal combustion phenomena.

The first series version of the MBKD is currently calibrated in more than ten series-production projects. In comparison to knock detection methods based on signal filtering in the time domain, it increases the detection quality by reducing the susceptibility for noise interferences. Methods from the field of Artificial Intelligence, Pattern Recognition, statistics, and optimized digital signal processing are combined to an improved approach for detecting knocking combustions and pre-ignitions. Results and experiences from various series calibration projects show the high generalizability and robustness against electrical and mechanical interferences of the new knock detection method. This leads to reduced knock control interventions, less misdetections and therefore to a reduced Real Driving Emissions (RDE) fuel consumption and an optimized drivability.

The MBKD method and software has shown its suitability for mass production due to the usage in various projects with different ECUs and engine variants (number of cylinders and displacement) with high customer satisfaction.

In a current development the first series version of the MBKD functionality is extended by reconstructing the physical knock and pre-ignition pressure characteristics based on signals of structure borne noise sensors. This allows us to predict sensor signal values, which cannot be detected directly or only at high costs in series-production vehicles.

The main benefit is a more specific control behavior in any engine operation point due to a better estimation of the damage potential of single abnormal combustions.