Fraunhofer-Gesellschaft

Publica

Hier finden Sie wissenschaftliche Publikationen aus den Fraunhofer-Instituten.

Modellgestützte Berechnung des Brennraumdruckes durch Auswertung von Winkelgeschwindigkeitssignalen der Kurbelwelle

 
: Fehrenbach, H.

FhG-Berichte (1990), No.4, pp.31-37 : Abb.,Lit.
ISSN: 0342-1953
German
Journal Article
Fraunhofer IITB ( IOSB) ()

Abstract
Many faults caused by faulty combustion and mechanics in multicylinder engines can be detected through measurement and analysis of the crankshaft's angular acceleration. Using a low-cost magnetic sensor near the flywheel teeth, this method is easily applicable for production, service and on-board diagnosis. Errors in angular acceleration signal due to noise and limitations of the measurement procedure can be minimized by appropriate digital signal processing. The measured waveforms are interpreted based on a model describing the relationship between input variable (pressure in the combustion chamber) and output (angular acceleration). Research efforts for a single-cylinder engine (four-stroke spark-ignition) with an additional reference pressure transducer in the combustion chamber permit numerical comparison between measured and computed results without superposition of effects of forces from several cylinders. In addition to gas pressure and inertia forces, the angle-dependent variat ions of torque due to friction and valve gear are taken into account. Comparisons between measurements and model results indicate a high accuracy (error 3%). By inversion of the developed model it is possible to estimate the combustion pressure from measured waveforms of the crankshaft's angular velocity with an overall accuracy of plus,minus 200mbar (conditions: nor load/1500rpm).

: http://publica.fraunhofer.de/documents/PX-24569.html