Combustion pressure estimation method of a spark ignited combustion engine based on vibration signal processing

Abstract

An estimation method of the combustion chamber pressure, in an internal combustion engine, based on the processing of the vibration (acceleration) signal of the cylinder head, at constant speed and no load conditions is presented in this paper. The model is created based on the comparison of the vibration and pressure signals around the peaks of highest vibration, after a preprocessing and filtering of the signal using the most similar frequency bands between the sources. A polynomial regression is used between the selected data points to generate the resulting model relating pressure and vibration (and average rotational speed per cycle, calculated based on the vibration peaks). The model is tested with measurements from two spark ignited engine test benches: a single cylinder engine and a four-cylinder engine. The resulting model has very low computational cost and can provide a very accurate estimation of general shape and magnitude of the pressure trace, but does not reflect strongly cycle by cycle variations. Testing the Normalized Root Mean Square Error (NRMSE), where the best value is 100 % the single cylinder engine scores were 63.52 % and 20.02 % for the points before and after the vibration peak. For the four-cylinder engine those values were: 82.47 % and 28.27 % respectively.

Procesamiento de señales no intrusivas para el monitoreo de condición de emisiones y análisis energético en un motor de combustión interna diésel

“…Esto demuestra el impacto positivo que se puede obtener al aplicar estas metodologías predictivas del mantenimiento, ya que se maximiza el tiempo operacional de los componentes del sistema, tan solo con ponerlas en práctica en el momento necesario sin invadir el funcionamiento de los motores. Un adecuado diagnóstico del MCI, a partir de las señales intrínsecas, debe estar anclado al estudio del funcionamiento holístico del motor, debe relacionar las variables dinámicas y termodinámicas del mismo (Romero-Piedrahita y Quintero-Riaza, 2003;Zapata-Mina et al, 2020) y debe implementar técnicas para determinar la presión en la cámara de combustión a partir de señales no intrusivas (Grajales et al, 2016). En la Universidad Tecnológica de Pereira, especialmente en el programa de Ingeniería Mecánica, se han realizado estudios relacionados con el motor de combustión interna (Quintero et al, 2020;Mejía et al, 2021;Valencia-Duque et al, 2021;Torres Morimtsu et al, 2019;Grajales y Quintero Riaza, 2019).…”