Performance benchmarks of pressure and fibre optics sensors for natural gas engine control

Abstract

Traditionally, the automotive industry has been using piezoelectric transducers for measuring cylinder pressure due to their higher frequency and relatively small size. However, there is the need to develop sensors that are capable of measuring other combustion parameters. An optical fibre sensor can give accurate readings of combustion characteristics (e.g. combustion species concentrations) with high temporal resolution within each engine cycle. Engine control systems incorporating these sensors can reduce harmful emissions levels and improve fuel economy as well as performing parametric monitoring for predicting emission levels. A strategic combination of the fibre optic sensor as part of the control system can be deployed in order to provide these benefits. This paper presents the design of a novel sensing scheme with a fibre optic sensory system capable of monitoring the combustion event as part of the natural gas engine control system with a minimal invasive technique. The robustness of the optical sensory system is compared with a pressure sensory signal and is used to analyse mass fraction burn and heat release. An integrated ignition controller is presented that will enable the ignition angle to be modified based on the measured optical combustion signal with a control technique to provide an optimal management of the engine performance. The technique presented in this paper was developed as part of a research and development programme. However, the results will also make a significant contribution to further deployment of the technology in production vehicles.