Concern over the ever-increasing stringent emission requirements and rising fuel costs has resulted in closer examination of the control of combustion in internal combustion engines. Natural gas is becoming a viable alternative fuel source, diversifying the transport fuel base, and a fuel potentially offering efficiency and environmental pollution benefits, compared with conventional fuels. Although the potential benefits of the fuel are acknowledged, there are clearly identifiable shortcomings in the control technology applied to the fuel and ignition management system. This paper presents the design of a novel sensing scheme with a fibre optic sensory system capable of monitoring the combustion event in a natural gas engine with minimal invasiveness. The optical sensory system is compared with a pressure sensory signal and used to analyse mass fraction burn and heat release. An integrated ignition controller is presented that enables 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.

A bre optics combustion intensity detection sensor is developed for the purpose of monitoring and controlling natural gas engines. The sensory system, which is based on the detection of the intensity of the combustion event, is mounted on the top of the engine block. Prior to implementation of the detection system, the accurate kinematics of the sensor probe within the combustion chamber needs to be identi ed while taking account of the geometric complexity of the engine design. This requires the understanding of the kinematics of probe position within the spatial relations of the engine block geometry that is likely to give a good coverage of the combustion processes. This paper therefore presents a new model that was implemented on natural gas engines but could also be used for identifying the appropriate location within the combustion chamber of any modern engine. An application example using the model is presented. The model provides the ability to monitor completely the stages of combustion within the cycle-to-cycle operation of the engine and use the signal thereof for management and control of the engine. Experience gained from the application of the model resulted in the development of the probe deployment rule discussed in this paper.

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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.