Knock Sensor based Virtual Cylinder Pressure Sensor 2019-01-0040
Typically the combustion in a direct injected internal combustion engine is open-loop controlled. The introduction of a cylinder pressure sensor opens up the possibility of a virtual combustion sensor which could enable closed-loop combustion control and thus the potential to counteract effects such as engine part to part variation, component ageing and fuel quality diversity.
Closed-loop combustion control requires precise, robust and preferably cheap sensors. This paper presents a virtual cylinder pressure sensor based on signal from the inexpensive but well proven knock sensor.
The method used to convert the knock sensor signal into a pressure estimate included phase correcting and filtering the raw signal, scaling after known thermodynamic laws and provided engine sensors as well as reconstructing parts of the signal with other known models and assumptions.
The modelled cylinder pressure shows high correlation with the measured pressure trace and it was concluded that it is possible to estimate many important combustion parameters - such as maximum pressure, mass fraction burned and total heat release - with the developed model.
Christian Rugland, Ola Stenlaas
KTH Royal Institute of Technology, Scania CV AB
International Powertrains, Fuels & Lubricants Meeting